Water Quality TestingWater Quality Testing

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What is water tested for?What is water tested for?

• Physical contentPhysical content

• Chemical contentChemical content

• Biological contentBiological content

Physical content: TurbidityPhysical content: Turbidity

TurbidityTurbidity is the cloudiness caused by is the cloudiness caused by suspended particles in the water suspended particles in the water (similar to smoke in air).(similar to smoke in air).

Good water should have low turbidity.Good water should have low turbidity.

Physical content: OdourPhysical content: OdourOdour may make water Odour may make water

objectionable to objectionable to consumers and may consumers and may indicate the presence indicate the presence of unwanted of unwanted chemicals.chemicals.

E.g. water might smell E.g. water might smell of rotten eggs, which of rotten eggs, which would indicate the would indicate the presence of hydrogen presence of hydrogen sulfide.sulfide.

Remember we test the odour of chemicals in the lab by “wafting.”

Physical content: ColourPhysical content: Colour

Same for colour.Same for colour.

E.g. a brown, red, or E.g. a brown, red, or yellow colour might yellow colour might indicate the presence indicate the presence of excess iron.of excess iron.

Chemical content: pHChemical content: pH

pH is a measure of the acidity or pH is a measure of the acidity or alkalinity of the water.alkalinity of the water.

Saltwater fish prefer an alkaline pH of Saltwater fish prefer an alkaline pH of 8.0 or above, but freshwater fish 8.0 or above, but freshwater fish prefer water between an acidic 5.5 prefer water between an acidic 5.5 and 7.5 (lakes will be slightly acidic and 7.5 (lakes will be slightly acidic from naturally acidic rainwater).from naturally acidic rainwater).

Chemical content: pHChemical content: pH

We don’t want our tap water too We don’t want our tap water too acidic, though, because it would acidic, though, because it would dissolve the metal in plumbing.dissolve the metal in plumbing.

Fortunately, most of the groundwater Fortunately, most of the groundwater sources of our tap water have been sources of our tap water have been neutralized by alkaline rocks and neutralized by alkaline rocks and soils.soils.

Chemical content:Chemical content:Dissolved OxygenDissolved Oxygen

Fish, invertebrates, plants, and aerobic Fish, invertebrates, plants, and aerobic bacteria all require oxygen for bacteria all require oxygen for respiration. respiration.

Chemical content:Chemical content:Dissolved OxygenDissolved Oxygen

Much of the dissolved oxygen in water Much of the dissolved oxygen in water comes from the atmosphere. After comes from the atmosphere. After dissolving at the surface, oxygen is dissolving at the surface, oxygen is distributed by current and distributed by current and turbulence.turbulence.

Algae and plants also deliver oxygen Algae and plants also deliver oxygen to water through photosynthesis. to water through photosynthesis.

Chemical content:Chemical content:Dissolved OxygenDissolved Oxygen

The main factor contributing to lower The main factor contributing to lower dissolved oxygen levels is the build-dissolved oxygen levels is the build-up of organic wastes since their up of organic wastes since their decay consumes oxygen.decay consumes oxygen.

Algal bloom

Chemical Content: HardnessChemical Content: Hardness

Water hardness is caused by dissolved Water hardness is caused by dissolved metallic ions from rocks and soils, metallic ions from rocks and soils, principally calcium and magnesium.principally calcium and magnesium.

Water hardness test strips

Chemical Content: HardnessChemical Content: Hardness

We care about the hardness of tap We care about the hardness of tap water in particular since hard water water in particular since hard water requires a considerable amount of requires a considerable amount of soap to produce a lather, and it also soap to produce a lather, and it also leads to scaling of hot water pipes, leads to scaling of hot water pipes, boilers and other household boilers and other household appliances. appliances.

Chemical Content: Other Chemical Content: Other IonsIonsWe can also test for negative ions like We can also test for negative ions like

nitrates and phosphates that might nitrates and phosphates that might come from manure or chemical come from manure or chemical fertilizers.fertilizers.

High nitrate concentrations can cause High nitrate concentrations can cause blood disorders, etc.blood disorders, etc.

Biological ContentBiological Content

There are three main types of There are three main types of microorganisms that can be found in microorganisms that can be found in drinking water: bacteria, viruses, and drinking water: bacteria, viruses, and protozoa. protozoa.

These can exist naturally or can occur These can exist naturally or can occur as a result of contamination from as a result of contamination from human or animal waste. Some of human or animal waste. Some of these are capable of causing illness these are capable of causing illness in humans. in humans.

Biological Content: Biological Content: E. coliE. coli

Biological content is determined by Biological content is determined by testing for testing for E. coliE. coli, a coliform , a coliform bacterium that is always present in bacterium that is always present in the intestines of humans and other the intestines of humans and other animals and whose presence in animals and whose presence in drinking water would indicate fecal drinking water would indicate fecal contamination of the water.contamination of the water.

The Test SiteThe Test Site

Water exists in Water exists in equilibrium with its equilibrium with its surroundings. Remove surroundings. Remove it and its it and its characteristics (e.g. characteristics (e.g. dissolved gases) will dissolved gases) will start to change, so start to change, so water is best tested at water is best tested at the site.the site.