Download - EHS COP Domestic Water (E) 8-04
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February 03 Version 1 (E)
Code of Practice for ReducingRisks Associated with Legionel la
in Domestic Services
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CODE OF PRACTICE FOR REDUCING RISKS ASSOCIATED
WITH LEGIONELLA IN DOMESTIC SERVICES
INDEX PAGE NO
Objective 2
Identification and assessment of risk 3
Preventing or reducing the risk from exposure toLegionella 4
Design 4
Operation 5
Inspection and maintenance 6
Cleaning and disinfection 7
- Pre-commission disinfection 8
- Remedial disinfection and cleaning 8- On-line/continuous disinfection procedures 10
- Water supply tank cleaning 11
Monitoring Programmes 12
- Cold water monitoring programmes 12
- Hot water monitoring programme 13- Action levels 14
Actions in the Event of an Emergency 16
Management and the selection, training and competence of personnel 17
Record keeping 18
Responsibilities of designers, manufacturers, importers, suppliers and
installers 19
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OBJECTIVE
1. To provide recommendations and guidance on precautionary measures required to maintaindomestic (hot and cold water) services in a manner which reduces the risks associated with the
proliferation of Legionella. Environmental Hygiene Services is a business unit of Nalco. The
following recommendations are not intended to replace any local regulations/guidancewhich must take priority when considering Legionellacontrol procedures. In the absenceof local regulations/guidance, the recommendations in this Manual are to be adhered to. In
production of this guidance document, consideration has been given to the global variations
employed for reducing the risk. The recommendations within this document are consistent
with the UK Legionnaires disease: The Control of Legionella Bacteria in Water Systems,OSHA (US), Australian and French guidelines. However, in certain detail, the strictest
guidance available has been deemed as good practice and incorporated into the international
standards for Nalco.
INTRODUCTION
2. This manual deals with engineered water systems which might be used in a way which creates
a reasonably foreseeable risk of legionellosis, in particular hot and cold water services.Although written for Environmental Hygiene Services personnel, this manual may form a
useful part of a site specific written scheme for reducing risk.
3. Humidifiers and air washers, spa bath, pools, water softeners, emergency showers, car washes,fire and sprinkler systems and many other systems using water, operating at temperatures in
excess of 20oC which can generate an aerosol, present a possible risk of Legionellosis.This
manual is specifically written for domestic hot water services, however, the systems
previously mentioned also have a requirement to be risk assessed, utilising similar principles
to those herein described. The key features of this assessment will identify the risk ofLegionella proliferation and the probability of exposing a susceptible population to a
contaminated aerosol. An adequate control scheme and management practices will also be
required. It is acknowledged that various geographical locations will have different
designs/operations of water systems and that local regulations may also differ.
4. System design and operation, methods of routine control, treatment and monitoring of the
water contained in these systems and recommendations for cleaning and disinfectionprocedures are considered. Guidance on the design of treatment programmes will be found in
the appropriate Operations Manual, as provided by the various Ondeo business units.
5. No two systems are identical and this manual can only be considered as a general guide.Where the unique nature of a system takes it outside the recommendations in this manual, the
principles should still be applied (ie as guided by the risk assessment) with appropriate
amendments being agreed between the responsible site representative, the responsible District
Management and the Site Management, with due regard to current regulations/guidance.
6. At all times, Environmental Hygiene Services employees are obliged to conform to local
Health and Safety regulations and any supporting information issued by local Health and
Safety departments. Reference is also made to the Nalco Health and Safety policy. In thismanual the UK Approved Code of PracticeLegionnaires Disease: the Control of Legionella
Bacteria in Water Systems is used as reference. This determines the minimum standardsthat can be applied. It should also be noted that the conclusion of the risk assessment might
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dictate requirements above this minimum in order to provide the most appropriate level of
programme performance and risk reduction. The reasons for the variation in standards shouldbe noted in the customer file and the log book.
7. It is recommended that effective documentation of the maintenance programme is available.
Log books, specifications and schedules are therefore essential with sufficient detail beingprovided to show that the scheme to reduce risk has been based on a valid Risk Assessment
and that it has been competently and effectively applied and implemented.
8. It is the responsibility of the Site Management, specifically the person on whom the statutoryduty (legal responsibility) falls, to ensure that an adequate Risk Assessment of the water
systems on site is carried out, with details held on file. Further, it is their duty to ensure that
people involved with the control of Legionella have adequate training qualifications and
experience to fulfil their duties in executing the risk management programme.
IDENTIFICATION AND ASSESSMENT OF RISK
9. It is the responsibility of the site management, specifically the person on whom the statutoryduty falls, to ensure that an adequate Risk Assessment is undertaken for the site and that
control measures detailed in the assessment are appropriately implemented. The Risk
Assessment must be current, as it forms the foundations of the whole risk management activity.
10. The Risk Assessment may be carried out by site personnel, if they have appropriate knowledge
and experience, or the task may be contracted out. Environmental Hygiene Services may
undertake this activity on behalf of the customer, but this does not form part of the
normal water treatment programme contract unless specifically detailed in the contractof supply. A competent person who has a sufficient understanding of the systems and the risk
factors must carry it out. They must also have an appropriate level of training.
11. The Risk Assessment will be sufficiently detailed so as to identify and assess the risk oflegionellosis from work activities and water sources on site, and the necessary precautionary
measures. This Risk Assessment must be reviewed if significant changes occur, or every two
years.
12. A Risk Assessment should not be confused with a site survey, which may be undertaken to
provide sufficient information to formulate a water treatment programme, or to enable the
provision of a quotation for future works. Nor should it be confused with asite audit, which
may be undertaken to provide an asset register of all water systems. A trained Risk Assessor,who has detailed understanding of the system and the risk factors, must carry it out. However,
this individual may require the assistance of a site contact person who can provide the
operational details. Both site audit and site survey documentation may form a useful part of
any Risk Assessment.
13. It is not the purpose of the Code of Practice Manual to define the requirements of a Risk
Assessment. An assessment is a requirement of good practice and where sites do not have an
assessment, it will be necessary for Environmental Hygiene Services to inform the responsibleperson on site of this requirement. It is appropriate to inform increasingly Senior Site
Management of this requirement if action is not taken to comply.
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PREVENTING OR REDUCING THE RISK FROM EXPOSURE TO LEGIONELLA
Design
14. The responsibilities held by Nalco and the customer site with respect to the written
scheme for reducing risk, must be clearly defined in the contract or quotation.Therefore, the respective operational responsibilities held by the various parties shouldform part of the business contract.
15. Good design and installation practice is essential for effective long-term maintenance.
Reference should be made to local standards and publications.
The following points concerning design should be noted if applicable:
(a) Installers should only use approved fittings and materials. Reference should be made
to local standards.
(b) If applicable, water supply tanks and other parts of the distribution system should be
well enclosed to prevent the entry of foreign matter.
(c) Overflows and air vents should be protected by appropriately sized rodent
screens/insect filters.
(d) Water supply tanks should not be oversized; 24 hour maximum storage capacity isrecommended. Multiple linked tanks should be avoided.
(e) Where two or more tanks serve the same system, they should be arranged such that
water flows through all tanks so that stagnation does not occur. This is normallyachieved by connection in series. Pipework should be arranged such that cleaning of
individual tanks can be undertaken without disconnecting the water supply.
(f) Water supply tanks should be readily accessible for cleaning and appropriate valvesand drain points should be fitted to facilitate this. No heating circuit should discharge
into a drinking water tank.
(g) Pipework should be designed and installed such that the entire system can beadequately and quickly drained and refilled.
(h) Pipework should be short and as direct as possible. Deadlegs should be avoided.
Point of use water heaters should be considered for low use or remote outlets.
(i) Cold water supply tanks and pipework should be installed such that heat pick-up is
minimised, eg. do not position close to a heat source, reduce solar gain, use insulating
materials and locate cold supply pipes below hot pipes.
(j) Calorifiers should be capable of heating their contents to the desired temperature
throughout. Stratification should be avoided by means of a shunt pump if necessary.
(k) Calorifiers should be readily accessible for cleaning and inspection and have aworking, accessible drain point.
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(l) Cold water supply tanks should be of corrosion resistant materials and installed in acool place.
(m) If fitted, accumulators should have diaphragms, which are accessible for cleaning.
(n) If fitted, thermostatic mixing valves should be set to give a temperature of not greater
than 43oC (109oF) and the pipe runs from the circulating main should be as short as
practicable (not more than 2m from the mixer to the shower head). These showers
should be used frequently or flushed regularly.
16. In designing a system care should be taken to address the following, if appropriate to the
system:
(a) Installation and maintenance of filtration equipment.
(b) Installation and maintenance of pre-treatment plant, such as water softeners
(c) Installation and maintenance of continuous disinfection equipment, such as UV units
and chlorine dioxide dosing and control systems.
(d) Installation of automatic monitoring and sampling equipment, such as temperaturedata loggers.
Operation
17. The following general points regarding operation should be noted
(a) Temperatures of 20-45oC (68-113oF) favour the growth of Legionella and these
temperatures should be avoided as far as possible in hot and cold water systems.
(b) Calorifiers/hot water storage tanks should operate at 60oC (140oF) with hot water
distribution giving a temperature of 50oC (122oF) at the taps within at least 1 minute.
The storage capacity and rate of recovery of the calorifier should be selected to meetnormal fluctuations in demand. With large calorifiers shunt pumps should be fitted
and run for 1 to 2 hours during periods of low demand to avoid stratification. Where
more than one calorifier is in use they should be installed in parallel and maintained at
least 60
o
C (140
o
F). If one is frequently out of use, it should be decommissioned anddrained.
WARNING: Above 43oC (109oF) there is a risk of scalding, and warning labels
should be displayed. This is particularly important where young children, the
elderly or those with sensory loss are involved. Where this is the case fail-safe,
thermostatically controlled mixing valves should be used. Such valves can presentshort, moderate temperature sections, which may support Legionella growth.
Continuous disinfection of the water is a viable alternative to temperature control.
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(c) Where high temperatures cannot be maintained due to operating peculiarities ordesign, then Thermal Disinfection can be applied. This involves raising the
temperature in calorifiers to 60oC (140oF) and circulating this high temperature water
throughout the system for at least 1 hour.
(d) If a calorifier or any substantial part of the system is on stand-by, its temperature
should be raised to 60oC (140oF) throughout for at least 1 hour before being brought
on line.
(e) Cold water supply tanks and cold water services should be maintained at temperatures
below 20oC (68oF), where practicable. Hot and cold water pipes should be insulated.
(f) Where sections of the system remain unused for long periods, a shower in a hotelroom for example, steps should be taken to run good quality water through them to
waste at least weekly or for sufficient time to ensure that their whole length has been
flushed.
Where difficulty is experienced in controlling Legionella colonisation of water
systems or temperature control is difficult for technical or other reasons, then
supplemental disinfection, eg. chlorine dioxide dosing using, for instance, anEnvirox system, should be considered as part of the risk control strategy.
(g) Where sections of a system have not been used or flushed for a period in excess of
one week, then it is recommended that a disinfection procedure should be carried outbefore being brought back into use.
(h) Where sections of a system are to remain unused for long periods, then consideration
must be given to isolating these sections of pipework and draining or possiblyremoving pipework and fixtures completely.
Inspection and Maintenance (Refer to monitoring section of additional details)
18. The following general points regarding inspection and maintenance should be noted:
(a) Calorifier (flow) temperatures should be checked monthly. Temperatures obtainedduring thermal disinfection should also be checked periodically and results recorded.
(b) Water temperatures at all outlets should be checked at least once annually and a
representative number, normally those nearest to and furthest from the calorifier,should be checked monthly (so called Sentinel Taps). Temperature checks should be
taken after running for 1 minute at full flow, for hot taps and 2 minutes at full flow for
cold taps.
(c) Temperature monitoring should be supported with regular microbiological testing
using dipslides, and Legionella testing to check the effectiveness of the control
programme. Legionellamonitoring is recommended in all situations, the frequency oftesting being guided by the risk assessment but as a minimum, quarterly.
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(d) Where biocides are used as the primary Legionella control and temperatures arereduced, monthlyLegionella samples are required.
(e) In systems where control is lost (eg. failure to maintain temperature or biocide
concentration) then weekly Legionella samples should be taken until control is re-established.
(f) Internal inspection of calorifiers should be undertaken annually, and cleaning and
disinfection should be carried out if there is a build up of scale or sludge.
(g) Accessible pipework and insulation should be inspected annually and refurbished if
necessary.
(h) Water supply tanks should be inspected annually, or more frequently if contamination
is suspected, and cleaned and disinfected if there is a build up of deposits, sludge or
contamination.
(i) Where elevated risk potential has been identified, close monitoring of the system
should be undertaken until the system can be shown to be in a stable operating
condition.
(j) Filters and strainers should be inspected monthly until an appropriate inspection
frequency is established, based on the rate of accumulation of debris. These items and
other pre-treatment plant may require periodic disinfection.
(k) Pre-treatment plant, sodium ion exchange water softening plant and dosing
equipment, such as chlorine dioxide systems, must be checked regularly in
accordance with the manufacturers instructions.
19. In some industries and properties, health care premises for example, specific standards are set.
Where these standards impose a higher frequency of testing or a more rigorous application of
standards, then they override the requirements of this Code of Practice.
CLEANING AND DISINFECTION OF DISTRIBUTION SYSTEMS
20. Cleaning and disinfection may be required under a number of circumstances and a variety ofoptions are detailed in the following paragraphs.
21. When chemical or thermal disinfection is being undertaken, warning notices must be posted.
Physical barriers, or tape, may also be necessary depending upon site requirements.
22. Chlorinated water of volumes greater than 5m3 (5000L) or as determined by local regulations,
must be neutralised before disposal. Similar precautions should be taken when using chlorine
dioxide.
23. Following disinfection, tanks should always be filled with fresh mains water.
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Pre-Commission Disinfection
The following details are recommendations for pre-commission disinfection. Reference
to local regulations/directives may also be necessary.
24. For installation within buildings:
(a) remove all visible dirt and debris from the water supply tanks and isolate supply and
outlet valves.
(b) fill tank and pipework with clean water, then drain until empty.
(c) re-fill will clean water and add sodium hypochlorite or chlorine dioxide to give a free
residual chlorine concentration of 50 mg/L in the water.
(d) leave tank to stand for 1 hour. If the concentration of chlorine or chlorine dioxide
falls below 50 mg/L then the disinfection time must be extended to 2 hours at 20
mg/L.
(e) open outlet valves, drain water from each draw-off fitting successively working away
from the tank. Close each draw-off fitting when the water discharged begins to smell
of chlorine, or chlorine dioxide is detected using test papers or test strips.
(f) the tank must not be allowed to drain during this operation and if necessary,
additional sodium hypochlorite or chlorine dioxide should be dosed to maintain the
residual concentration as in (d) above.
(g) the tank and pipework should be allowed to stand for 1 hour minimum.
(h) the free residual chlorine or chlorine dioxide in the water discharged from the tapfarthest from the tank should be measured. If after the 2 hour period this
concentration is less than 20 mg/L, the disinfection process must be repeated.
(i) after disinfection, the tank and pipework should be flushed with clean water until the
free residual chlorine or chlorine dioxide concentration, at each draw-off outlet, is no
greater than that of the incoming water mains. The building occupier should also be
warned that some discolouration may occur and that the system should be operateduntil all discoloured water is discharged.
Remedial Disinfection and Cleaning
During normal operation, it is possible for hot and cold water services to becomecontaminated and disinfection will be required.
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25. Where a system is known to contain hardness or corrosion deposits, or an accumulation of
sludge in pipework, supply tanks or calorifiers then chemical cleaning may also be required.
26. Where a system has had engineering works carried out, such as extensions or alternations,
disinfection will be required. For localised repairs, providing new junctions or fittings are
disinfected before use (immerse for 30 minutes in a dilution of chlorinating solutionmaintained at a minimum of 200 mg/L free chlorine), flushing is all that is normally required.
27. Where a system has not been in regular use and not regularly flushed, ie. out of use for more
than six weeks, disinfection is required before the system is brought back into use.
28. NOTE: Before any remedial disinfection or cleaning is undertaken, a thorough inspection of
the system should be carried out. Equipment that comes into contact with the water, pumps
and vacuums, for example, should be disinfected before use.
29. Disinfection using chlorine or chlorine dioxide:
(a) Remove all visible dirt and debris from the water supply tank and isolate supply andoutlet valves;
(b) Fill tank and pipework with clean water then drain until empty;
(c) Re-fill with clean water and add sodium hypochlorite to give a free residual chlorine
or chlorine dioxide concentration of 50 mg/L in the water;
(d) Leave tank to stand for 1 hour;
(e) Open outlet valves, drain water from each outlet, successively working away from the
tank. Close each outlet when the water discharged begins to smell of chlorine or
chlorine dioxide is detected using test papers or test strips;
(f) The tanks must not be allowed to drain during this operation and if necessary,
additional sodium hypochlorite or chlorine dioxide should be dosed;
(g) The tank and pipework should be allowed to stand for 1 hour;
(h) The free residual chlorine or chlorine dioxide in the water discharged from the tap
furthest from the tank should be measured. If after the 2 hour period thisconcentration is less than 20 mg/L the disinfection process must be repeated;
(i) After disinfection, the tank and pipework should be flushed with clean water until the
free residual chlorine concentration, at each draw-off fitting, is no greater than that ofthe water suppliers mains. Should the system remain unused for more than 1 week,
then the disinfection process should be repeated.
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30. Where shower heads are found to be scaled, they should be removed and acid descaled, rinsed
and re-fitted
It may be impractical to carry out a full clean and disinfection with system refurbishment. On-
line disinfection may provide an alternative. If this option is taken, the reasons for not carrying
out a full clean and disinfection must be noted in the site maintenance log with full agreementof the customer and confirmed in writing.
On-Line/Continuous Disinfection Procedures
Systems which are known to experience contamination, or where risks associated with
Legionellaare high, may require some form of continuous protection.
31. Continuous disinfection may be undertaken using chlorine dioxide if permitted by local
regulations/guidance. Chlorine dioxide has a designated limit in drinking water of 0.5 mg/Ltotal oxidant in the UK, 1.0 mg/L in France and 0.8 mg/l in the USA (refer to local regulation)
and this can be applied on a continuous basis to hot and cold water services. Unlike chlorine,this product does not add significantly to taste or odour. Chlorine dioxide can be used with
accurate dosing and control equipment to effect control ofLegionella in such systems, with the
additional benefit of providing efficacy against biofilms.
The quantities of chemical in the reservoir, the rate of addition of the chemical and the
concentration achieved at sentinel taps should be monitored on a monthly basis. The
concentration of chlorine dioxide at the Sentinel taps should be at least 0.1 mg/L at cold water
outlets. If biofilm removal is being sought, then ideally >0.4 mg/L C102 is required.
32. On an annual basis, the chlorine dioxide concentration of a representative number of cold
water outlets should be checked and a concentration of at least 0.1 mg/L achieved, unless
biofilm removal is sought, then the concentration should be 0.4 mg/L.
33. Continuous disinfection may be undertaken using chlorine. Continuous chlorination may be
undertaken with a free residual chlorine concentration of 0.5-2 mg/L being maintained
throughout the system. This may be achieved through the use of water meter controlledsodium hypochlorite dosing or electrolytic chlorination.
34. Continuous disinfection may be undertaken using ultra violet radiation. UV units may be usedon outlets from water supply tanks to reduce the risk of organisms entering distributionpipework. Units may also be more effectively fitted at point of use. It should be noted that
UV has no residual effect and therefore has no effect on established biofilms or contamination,
which occur downstream of the unit, unlike continuous chlorine dioxide or chlorine addition,
where biocidal activity will be evident throughout the system.
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35. Continuous disinfection may also be undertaken using ionisation (the addition of copper and
silver ions). These levels are under constant review and current value should be confirmedbefore using this form of disinfection. It is recommended that the supplier of such units be
consulted. However, it should be noted that systems using hard waters are those with an
operating pH in excess of 7.6 may have difficulties in maintaining clean electrodes in the
ionisation unit, and in establishing satisfactory silver levels. Concentrations of Ag of at least20 g/L and copper concentrations of 400 g/L are necessary at all Sentinel taps, which should
be checked on a rotational basis at least annually. The installation should be checked with the
water supply service provider for compliance with the Water Regulations. This form of
treatment is not allowed under French Guidance (Circulaire DGS 2002/243)
Water Supply Tank Cleaning
Annual inspection may reveal that cleaning and disinfection of the water supply tank isrequired.
36. Tanks may be disinfected using chlorine:
(a) If organic materials contaminate water supply tanks then disinfection with 50 mg/L
chlorine or chlorine dioxide for at least 1 hour (or 20 mg/L for at least 2 hours) shouldbe undertaken before the actions below.
(b) Close inlet valve, drain to level of outlet, plug outlet to distribution system and
remove loose deposits by pump and vacuum.
(c) Remove adherent deposits by chemical treatment and manual cleaning.
(d) Organic fouling should be removed and any stubborn deposits treated withchlorine/biocides/alkali to facilitate removal.
(e) Oil and grease should be treated. Steam cleaning or high pressure jetting can be
undertaken if necessary. Remove all loose deposits.
(f) Fill tank with clean water then drain or pump to waste until empty. Waste must not
be drained through the system at any time. More than one flush may be required.
(g) Remove plug from outlet to distribution system.
(h) Re-fill with clean water and add sodium hypochlorite to give a free residual chlorine
concentration of 50 mg/L in the water.
(i) The tank should be left flooded with chlorinated water for a minimum of 1 hour with
50 mg/L chlorine (or minimum 2 hours with 20 mg/L chlorine).
(j) After standing, the tank should be flushed with clean water until the free residualchlorine concentration is no greater than that of the water suppliers mains.
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(k) NOTE: Where the volume of wastewater exceeds 5m3 (5000L) it is recommended thatthe water be neutralised before disposal. The method of neutralisation is specified on
the procedure log sheet. Waste must not be drained through the system.
37. Following cleaning, the tank internal surfaces may be painted using a locally approved coating,if appropriate. Tank painting must be carried out on dry, well prepared surfaces and each stage
of the coating must be given sufficient time to cure. Failure to observe these two constraints
will lead to a poor finish, poor quality water and additional remedial works. Where internal
surfaces are in a particularly poor condition, where there are perforations and leaks, or wheretime constraints dictate that there would be insufficient time to allow a coating to cure, the use
of a butyl weldable plastic sheet or fibreglass lining may be appropriate. Time must be
allowed for surface preparation and curing.
38. The repair of internal surfaces can extend the useful life of a tank but this should not be seen as
an indefinite extension, and replacement of badly corroded or damaged tank is advised.
39. Following any refurbishment of the internal surfaces, disinfection must be carried out asdetailed in the preceding protocols, before the tank is brought back into use.
MONITORING PROGRAMMES
Cold Water Monitoring Programmes
40. Monitoring programmes must include
(a) Annual inspection of water supply tank, if appropriate, or more frequent inspection if
contamination is suspected. Cleaning and disinfection to be carried out if inspection
indicates that this is required.
(b) Annual inspection of accessible pipework and insulation. Refurbishing to be carried
out if required.
(c) If applicable, check cold water storage temperatures every 3 months. Temperatures
must be maintained below 20oC (68oF). In some countries this temperature may be
exceeded and so more frequent testing is advised.
(d) If applicable, monitoring of disinfectant level if chlorine, chlorine dioxide or
ionisation are used as part of theLegionella control strategy.
(e) Monthly check of temperatures at the nearest and furthest taps from a storage tank orpipework system, which should be less than 20oC (68oF) after running for 2 minutes.
(f) Temperature checks on all taps/outlets on a rotational basis at least annually.
(g) Annual Legionella testing. If an alternative strategy to temperature control is
employed, more frequent sampling may be required, ie monthly until control is
established.
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(h) Quarterly on site checks of cold water storage and sentinel taps using Heterotrophic
Plate Count (HPC) Total Count samplers.
41. Monitoring programmes may also include
(a) Quarterly total viable count (TVC) monitoring at the nearest and furthest taps from astorage tank or pipework system, via an accredited laboratory. This is not a test of
drinking water (potability) quality. (See next page).
(b) Cold water systems can also be monitored on a quarterly basis for coliforms, E.coli,amoebae and protozoa. Results from these analyses will indicate the general hygiene
conditions within the system.
(b) QuarterlyLegionella monitoring of sentinel taps (nearest and furthest outlets).
Hot Water Monitoring Programmes
42. Hot water systems generally present a greater risk than cold systems due to the highertemperatures and aerosol producing fittings such as showerheads, and careful monitoring is
essential.
43. Monitoring programmes must include:
(a) Annual inspection of calorifiers where practicable. Cleaning and disinfection to be
carried out accordingly. Removal of accumulated sludge from calorifier base.
(b) Monthly temperature checks at calorifier (maintain minimum 60oC (140oF)).
(c) Temperature checks at all taps/outlets at least annually. A representative number of
taps/outlets should be checked monthly. After 1 minute running, the temperatureshould be 50oC (122oF) at all outlets from a storage tank or pipework system.
(d) Monitoring of disinfectant and disinfection byproduct concentrations to ensure that
they remain within guidelines/regulations.
(e) Annual inspection of accessible pipework insulation. Refurbish as necessary.
(f) Cleaning and disinfection of outlets as inspections require.
(g) Little used outlets flush through and purge to drain weekly.
(h) Shower heads and hoses dismantle, clean and descale quarterly.
(i) Quarterly Legionella testing should be carried out to verify the efficiency of
temperature control scheme. If an alternative strategy is employed, ie chemical
application, monthly or more frequent sampling is required.
(j) Monthly on site checks using HPC Total Count Samplers at calorifier and furthest
point in pipework.
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44. Monitoring programmes may also include:
(a) MonthlyLegionellamonitoring.
(b) Quarterly TVC monitoring via an accredited laboratory if applicable.
(c) Hot water systems can be monitored forPseudomonasquarterly.
Action Levels
45. HPC Total Count Samplers may be used to monitor the general planktonic bacterial population
in the water, but this will not indicate the presence, or otherwise, of Legionella. HPC Total
Count Samplers do give an indication of the overall effectiveness of control measures, but do
not provide any information on biofilms.
Depending on geographical location, bacterial levels deemed under control may vary. In theUS, levels of less than 500 CFU/ml are recommended whilst in certain European states, counts
are not to exceed normal trends established through regular testing. However, in bothexamples, Coliform andE.colicounts are expected to be negative. Counts for these organisms
indicate a breech in hygiene control.
46. Testing for Legionellato monitor the efficacy of precautionary measures as part of a plannedmonitoring programme provides useful supporting information. It will provide information on
the effectiveness of the control programme and indicate whether further assessment of the risk
is necessary.
47. More frequent Legionellasamples may be required from areas of high risk, eg. aged personshomes, hospital wards with at risk patients. When an outbreak is suspected or has been
identified, Legionella sampling should be undertaken prior to any remedial action.
48. When Legionellatesting has been undertaken, the results should only be presented to the
sites nominated responsible person or their nominated deputy.
The actions in Tables A, B and C are routine responses to test results, for
(a) UK and other European guidance documentation (Table A)
(b) US guidance documentation (Table B).In the absence of local guidance, it is recommended that actions be taken following
the recommendation in table A. This will offer a lower risk rating.
(c) French guidance (Table C) for 1) Spas / thermal bathing waters / hospitals with highpopulations of immune deficient patients and 2) General Hospitals/hotels etc.
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TABLE A
Legionellabacteria
(CFU/L)
ACTION REQUIRED
Equal to or less than 100 Inform customer, file results and
maintain current control regime
One or two samples above 100 Resample system, review riskassessment and control measure to
identify remedial action
Majority of samples are positiveor a count is above 1000
Disinfection or thermal pasteurisationshould be implemented. Immediately
review risk assessment to identify
remedial action.
TABLE B
Legionellabacteria
(CFU/ml)ACTION REQUIRED
Less than 10 Inform customer, file results and
maintain current control regime
10-99 Prompt cleaning and/or biocidetreatment
More than 100 Immediate cleaning and/or biocide
treatment
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TABLE C
Legionellabacteria
(CFU/L)
ACTION REQUIRED
1)Less than detection limit(50 CFU/L) Spa/thermal waters etc, acceptable
control. If greater than detection
limit, stop system and clean &
disinfect
2)Less than 1000 General Hospitals/Hotels: Inform
customer, file results and maintaincurrent control regime.
2)More than 1000 Implement all necessary actions toreduce level below 1000 CFU/L.
Remedial action should include resampling of the system and consideration of
continuous disinfection, eg application of chlorine dioxide.
48. Where a system is positive forLegionella, always inform the responsible District Manager andthe customers nominated responsible person or higher in the reporting chain.
ACTIONS IN THE EVENT OF AN EMERGENCY (OUTBREAK OF LEGIONELLOSIS)
49. In an emergency, it is important to ensure all documentation is kept up to date and filedappropriately. All actions and meetings must be noted and copies of file notes, minutes, etc
kept in the customer file. Local Environmental Health regulations should be referred to.
Reference should be made to procedures/guidance at local level.
Under no circumstances should contact be made with the press/media. Any queries of thisnature must be referred to the respective District Management.
50. If the domestic water system is confirmed as being involved in an outbreak of
Legionnaires Disease, then the Environmental Hygiene Services Emergency Response
Programme should be employed.
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MANAGEMENT AND THE SELECTION, TRAINING AND COMPETENCE OF
PERSONNEL
51. The statutory duty holder, the individual upon which the statutory duty falls on any given site,
is responsible for appointing a person, or persons to take managerial responsibility for
implementing precautionary measures. This person is sometimes called the responsibleperson.
52. It is the responsible persons duty to ensure that all persons involved in the reducing of risks
associated withLegionellahave sufficient ability, experience, instruction, information, trainingand resources to carry out their work safely and competently. Environmental Hygiene Services
training courses may offer a means of supporting this duty. Records should be maintained at
the customer premises and may form part of the log book.
53. Where consultants are used, it is also the duty of the responsible person to ensure their
competency. Training records and other relevant details of field personnel are available for
inspection by site management.
54. The responsibilities and lines of communication must be clearly defined for all persons
involved in this activity. These responsibilities and communication procedures should be
periodically reviewed. This is the responsibility of site management, but it may be usefully
addressed during programme/contract review.
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RECORD KEEPING
55. It is the responsibility of site management to maintain appropriate records, including:
(a) the names and position of those persons appointed under the written scheme to reduce
risk;
(b) the Risk Assessment;
(c) the name and position of the person or persons who carried out the assessment and
their qualifications;
(d) the written scheme for reducing risk;
(e) details on personnel and lines of communication involved in the scheme;
(f) records of plant use;
(g) records of work carried out by site or sites contractors;
(h) records of implementation of the scheme;
(i) Log books and associated risk assessment should contain as a minimum:
- a description of the system including diagrams and schematic drawings,
identification of water supply tanks, inventory of fittings and identification of
relevant items of pre-treatment plant, volume of water in systems;
- details of the Risk Assessment and the management and monitoring scheme;
- details of inspection procedures;
- records of water temperature, operation of pre-treatment plant, inspection and test
results, cleaning and disinfection operations, any works undertaken on the system,
any works undertaken as a result of inspections or testing (Action Defect Log).
The person carrying out the work should sign all these records.
These log books should also detail the personnel responsible for actions under the
scheme, including contractors and sub-contractors. This Manual may usefully be
included in the written scheme of preventative maintenance. Records should beretained for a minimum of 5 years. Electronic version of log books are also
acceptable. However, electronic files and data should regularly be duplicated in case
of loss of information.
56. It is the responsibility of Environmental Hygiene Services personnel to indicate which records
should be kept by both parties, to establish where they should be kept and who is responsible
for their maintenance. These records should be appropriate to the contractual arrangementswith the site and should include:
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(a) current contract;
(b) details of the programme and recommendations, which must in the first instance,
comply with the relevant industry standard or this Manual (reference paragraph 14);
(c) any Risk Assessment, water hygiene survey, site survey or asset register undertaken
by Environmental Hygiene Services;
(d) any laboratory test certificates includingLegionella test results;
(e) Completion/Chlorination Certificates or Reports;
(f) site visit reports including any monitoring records;
(g) a contact chain if that is not recorded in (c) above.
57. All records kept in accordance with paragraph 55 and 56 should be preserved throughout theperiod for which they remain current and for at least five years, notwithstanding the
requirement of any relevant quality system.
RESPONSIBILITIES OF DESIGNERS, MANUFACTURERS, IMPORTERS, SUPPLIERS
AND INSTALLERS
58. It is the responsibility of the designer, manufacturer, importer or supplier of plant and watersystems to ensure that risk is avoided or that the system will be safe and without risks to health
when used at work. Site Management should be advised to obtain assurances in this respect.
59. Information should be provided in writing concerning risk, and operation and maintenance.Site Management should be advised to obtain such information.
60. Environmental Hygiene Services is responsible for ensuring the provision of appropriate
Health and Safety information on all products supplied, that limitation of expertise or serviceor products are defined in the contract. Also that personnel employed are appropriate to carry
out tasks competently and safely and carry out the appropriate Risk Assessments, under the
Management of Health and Safety at Work Regulations before commencing work.
Environmental Hygiene Services will also recommend a schedule that will allow both partiesto review the contract covering the Management and Control ofLegionella.
61. It may be necessary for additional testing to be undertaken to ensure that the systems will be
safe for the work intended. This is the responsibility of the supplier. Site Management shouldbe advised of this.
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62. If the customer cannot agree to the recommendations made, then a programme should be
agreed providing a practical alternative which does not contravene the requirements of anylocal regulations/guidance and still meets the needs of the customer. However, the reasons for
not following our recommendations must be stated on file. This manual is intended as
guidance for the minimum standard. Since these guidelines are deemed the minimum
standard, any deviation to recommendations must be proved to be more effective than thoseoutlined.
63. Nalco will only recommend programmes for which they hold test data to indicate their
efficiency in the control ofLegionellain engineered water systems.
64. It is the responsibility of the customer to inform Environmental Hygiene Services of any
changes in operating conditions. Such changes may necessitate a review of the Risk
Assessment.
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NOTICE:
No warranty as to the completeness of the information is given. There must be an ongoing
programme of due diligence, both observations, record keeping and actions. Regularmaintenance schedules are critical to the operation and safety of the systems included in the Risk
Assessment. Nalco disclaims all liability and responsibility for any direct or indirect loss or
damage that may be suffered through reliance on any information contained in or omitted from
this document, and no person should act solely on the basis of the information contained in thedocument without taking appropriate professional advice about obligations in specific
circumstances.
The Nalco programme is designed to reduce health-related risks associated with the growth of
Legionella within domestic and industrial water systems. However, if the recommendedpractices are followed as outlined, then health-related risks from other waterborne pathogens
will likewise be reduced. While recommendations from Environmental Hygiene ServicesHygiene are designed to reduce health-related risks to ensure the overall health and safety of
your employees, associates, patients, and visitors, no programme can eliminate all health-related risks. In addition, recommended practices presented herein do not guarantee that water
quality within the assessed systems will meet governmental or trade standards. Local
regulations override specific recommendations where relevant.
Nalco Company 1601 W. Diehl Rd. Naperville, Illinois 60563-1198
SUBSIDIARIES AND AFFILIATES IN PRINCIPLE LOCATIONS AROUND THE WORLD