Glossary

Chloramine
is a compound created when chlorine is added to water containing ammonia. It is not as strong a disinfectant as chlorine and requires much longer contact time in order to destroy bacteria and viruses. However, it remains in water longer than chlorine so can be useful in preventing growth of biofilm in waterworks facilities that have long distribution systems.

Waterworks systems using groundwater for source water may create chloramines during the disinfection process because ammonia is often naturally occurring in the groundwater. Operators of treatment systems using surface water sources may choose to create chloramines by adding ammonia, particularly if they have long distribution systems.

Chloramine should be removed for water supplies used for dialysis patients and must also be removed from water used in fish tanks.

Chlorine
is the most common disinfectant used in drinking water treatment. It is an oxidant and is very effective in destroying bacteria and viruses.

Chlorine Dioxide
is a powerful oxidant used in disinfection but it is more difficult to handle than other forms of chlorine. It must be generated on-site and requires trained staff to manage it.

Chlorine residual
is the amount of total chlorine maintained in treated drinking water as it travels through a distribution system. It can be free chlorine, combined chlorine (chloramines), or a combination of both.

Chlorine, Combined
is a measurement of the amount of chloramines produces as a result of the reaction of chlorine with ammonia present in water.

Chlorine, Free
is a measurement of the amount of the chlorine available after a portion has been used up in reactions with the substances present in water.

Chlorine, Total
is a measurement of both free and combined chlorine.

Coliform bacteria
are naturally occurring bacteria used as an indicator of whether water is safe for human consumption. While most coliform bacteria are harmless, their presence indirectly suggests that disease-causing bacteria could also be present. Testing of coliform bacteria is done in the number of colony forming units found per 100 millilitres of water sampled (CFU/100mL).

Coliform bacteria, fecal
are a group of coliform bacteria that are found in the intestines of warm-blooded animals and humans and are shed in feces. The species of fecal coliform, called Escherichia coli (E. coli), is of particular concern if found in drinking water because a strain called E. coli 0157:H7, is extremely harmful to humans if ingested. The MAC for fecal coliform is 0 organisms detected in 100 mL of sample.

Coliform bacteria, total
is a measure of the amount of coliform bacteria found in a water sample and is used as an indicator that contamination may have occurred or that water treatment processes are not working properly. This triggers a repeat of the treatment process. The MAC for total coliform is no organisms detected in 100 mL of sample.

Confluent Growth
is the term used to describe when the general bacteria population found in a water sample is so excessive it prevents the detection of any harmful bacteria. Re-sampling is always necessary.

Cryptosporidium
are single celled parasites (protozoa) that live in the intestines of animals and humans. They are passed through feces in the form of oocysts. Water contaminated with fecal matter may contain cryptosporidium oocysts that, if ingested, will cause a severe gastrointestinal illness called cryptosporidiosis. Oocysts are highly resistant to chlorine but can be effectively. removed from drinking water supplies using ultraviolet light.

Disinfectant
is a chemical (commonly chlorine, chloramines or ozone) or a physical process (such as ultraviolet light) that kills unwanted microorganisms in drinking water.

Disinfection by-products
are chemical compounds formed when chlorine reacts with natural organic matter in water.

E. coli (Escherichia coli)
are a type of fecal coliform bacteria. A particular strain, called E. coli 0157:H7, has been found to be extremely harmful to humans if ingested. It produces a protein toxin that causes severe damage to the intestinal cells of infected individuals. The MAC for E. coli is 0 organisms in 100 mL of sample.

Giardia
are single celled parasites (protozoa) that live in the small intestine of animals or humans. They are passed through feces in the form of cysts. Water that is contaminated with fecal matter may contain Giardia cysts. If ingested, they cause a gastrointestinal illness called Giardiasis or Beaver Fever.

Groundwater under the Influence
or groundwater under the influence of surface water is groundwater that is found below surface of the ground and is in contact with surface water. It may also be referred to as ‘groundwater under the direct influence of surface water’ (GWUDI).

Hardness
is the measure of the amount of certain dissolved minerals in water, particularly calcium and magnesium. Hardness is the property in water that causes excessive soap consumption and encrustation in boilers, water heaters, pipes and cooking utensils. Since there are no know health-related effects associated with these minerals there is no MAC for Hardness. However, water supplies with >270 mg/L are considered poor.

Heterotrophic Plate Count (HPC)
is a measure of the total number of bacteria of all types present in the water. Large concentrations of a general bacterial population can hinder the detection of E. coli bacteria.

Inorganic Contaminants
are mineral-based compounds such as metals, nitrates and arsenic that are naturally occurring in water or have been introduced through human activities such as farming and manufacturing.

Maximum Acceptable Concentrations (MACs)
are established by Health Canada for substances that are known or suspected to cause adverse effects on human health. MACs are determined based on the assumption that lifelong exposure to drinking water containing the substance, at that concentration, may cause adverse health-related problems.

Organic Contaminants
are carbon-based chemicals such as pesticides and solvents that are introduced into water sources through human activities such as farming and manufacturing.

Pathogens
are microorganisms like bacteria (E. coli), protozoa (Cryptosporidium, Giardia) and viruses (hepatitis A and E) that cause gastrointestinal illness in humans, when ingested. These illnesses are usually non-life threatening but can be very serious in small children, the elderly or immuno-compromised individuals.

pH
is a measure of the hydrogen ion concentration in water, and determines whether water is acid or alkaline. A pH of 7.0 indicates a neutral condition (neither acid nor alkaline). Water below 7.0 is acidic and tends to corrode plumbing fixtures and faucets. Water above 7.0 is basic and tends to cause incrustation and scaling problems. Values between 6.5 and 8.5 are generally acceptable for drinking water. High pH waters require higher doses of disinfectant to destroy pathogens in drinking water systems. Small changes in the pH level of water can significantly alter its chemistry.

Temperature
of water will affect the efficiency of water treatment processes. Low temperature decreases efficiency of treatment processes and high temperatures enhance the growth of nuisance organisms. This makes it a crucial component of treatment design.

Trihalomethanes (THMs)
are disinfection by-products created when chlorine reacts with natural organic matter in water. Chloroform is the most frequently detected THM detected in drinking water supplies. The health risks associated with THMs are currently being assessed by Health Canada.

Turbidity
is a measure of the cloudiness of water, caused by the presence of suspended particles of sediment, organic and inorganic matter. High turbidity levels can interfere with drinking water treatment processes because the particulate matter in the water provides nutrients for pathogens that may be present, and it reduces the effectiveness of disinfectants in destroying them. Turbidity is measured in nephelometric turbidity units (NTUs).