Water Quality Testing SVN3E

What is water tested for? Physical content Chemical content Biological content

Physical content: Turbidity Turbidity is the cloudiness caused by suspended particles in the water (similar to smoke in air). Good water should have low turbidity.

Physical content: Odour Odour may make water objectionable to consumers and may indicate the presence of unwanted chemicals. E.g. water might smell of rotten eggs, which would indicate the presence of hydrogen sulfide. Remember we test the odour of chemicals in the lab by “wafting.”

Physical content: Colour Same for colour. E.g. a brown, red, or yellow colour might indicate the presence of excess iron.

Chemical content: pH pH is a measure of the acidity or alkalinity of the water. Saltwater fish prefer an alkaline pH of 8.0 or above, but freshwater fish prefer water between an acidic 5.5 and 7.5 (lakes will be slightly acidic from naturally acidic rainwater).

Chemical content: pH We don’t want our tap water too acidic, though, because it would dissolve the metal in plumbing. Fortunately, most of the groundwater sources of our tap water have been neutralized by alkaline rocks and soils.

Chemical content: Dissolved Oxygen Fish, invertebrates, plants, and aerobic bacteria all require oxygen for respiration.

Chemical content: Dissolved Oxygen Much of the dissolved oxygen in water comes from the atmosphere. After dissolving at the surface, oxygen is distributed by current and turbulence. Algae and plants also deliver oxygen to water through photosynthesis.

Chemical content: Dissolved Oxygen The main factor contributing to lower dissolved oxygen levels is the build-up of organic wastes since their decay consumes oxygen. Algal bloom

Chemical Content: Hardness Water hardness is caused by dissolved metallic ions from rocks and soils, principally calcium and magnesium. Water hardness test strips

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

Chemical Content: Other Ions We can also test for negative ions like nitrates and phosphates that might come from manure or chemical fertilizers. High nitrate concentrations can cause blood disorders, etc.

Biological Content There are three main types of microorganisms that can be found in drinking water: bacteria, viruses, and protozoa. These can exist naturally or can occur as a result of contamination from human or animal waste. Some of these are capable of causing illness in humans.

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

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