Northwest Territories Drinking Water Quality Database
Definitions
Aesthetic - A characteristic of drinking water that does not affect human health. Typically relates to the taste, smell, or look of the water, or a tendency to build up scale, or stain clothing or plumbing fixtures.
AO- Aesthetic Objective. A maximum concentration, set in the Guidelines for Canadian Drinking Water Quality, above which water is considered unpleasant because of taste, odour, colour, tendency to build up scale, etc. Does not affect human health.
Boil Water Advisory - A notice advising the public to boil drinking water at a rolling boil for at least 1 (one) minute. This advisory is issued when health officials determine that local drinking water may not be safe to drink, cook or wash with.
Chlorination – Chlorine is the most common chemical used worldwide to disinfect water. When used as a primary disinfectant, chlorine is a very effective disinfectant against bacteria and viruses. It is also used as a secondary disinfectant to maintain a residual chlorine concentration to prevent microbiological growth throughout the distribution system. All drinking water supply systems must maintain a residual chlorine concentration.
Class 1 Water Treatment System - Water treatment plants (WTPs) are classified according to the complexity of the treatment system, the quality of the raw water source, the number of people that rely on the system for safe drinking water, and the chemicals used in the treatment process. Most Class 1 WTPs in the Northwest Territories use filtration and chlorination to ensure safe drinking water. (Compare to Class 2 Water Treatment System and Small System). The typical NWT Class 1 plant uses a groundwater source.
Class 2 Water Treatment System - Water treatment plants (WTPs) are classified according to the complexity of the treatment system, the quality of the raw water source, capacity of the system, types and degrees of process controls and instrumentation, chemicals used in the treatment process and the treatment and disposal of waste such as backwash water, sludge and residuals. Class 2 systems are more complex than Class 1 Water Treatment System and Small System. A typical NWT Class 2 water treatment process may begin with screening to remove coarse suspended particles. The water then moves into a mixing chamber for flash mixing where a coagulant is added to help bind small particles together to form slightly larger particles called 'micro flocs'. The chemically treated water then flows into a flocculating chamber where another chemical, called coagulant aid, is added and the water is slowly stirred. This action will encourage and promote larger flocs to form that can be settled out more easily when the water passes through the sedimentation tank. After sedimentation, the water flows through a multi-media filter as a final polishing step to remove any flocs that may get carried over into the filter. As a final treatment step, chlorine is added to the water to disinfect it before it is stored for distribution.
Class 3 Water Treatment System - Water treatment plants (WTPs) are classified according to the complexity of the treatment system, the quality of the raw water source, capacity of the system, types and degrees of process controls and instrumentation chemicals used in the treatment process and the treatment and disposal of waste such as backwash water, sludge and residuals. Class 3 systems are the most complex water treatment systems used in the Northwest Territories. (Compare to Class 1 and Class 2 Water Treatment Systems and Small System). A typical NWT Class 3 water treatment process may begin with screening to remove coarse suspended particles follow by pretreatment to condition the raw water for more effective chemical coagulation (such as pH adjustment). The water then moves into a mixing chamber for flash mixing where a coagulant is added to help bind small particles together to form slightly larger particles called 'micro flocs'. The chemically treated water then flows into a flocculating chamber where another chemical, called coagulant aid, is added and the water is slowly stirred. This action will encourage and promote larger flocs to form that can be settled out more easily when the water passes through the sedimentation tank. After sedimentation, the water flows through a multi-media filter as a final polishing step to remove any flocs that may get carried over into the filter. Further chemical treatment may require for corrosion and pH control prior to storage. As a final treatment step, chlorine is added to the water to disinfect it before it is stored for distribution.
Coagulation - Coagulation is the process that brings very small particles (or colloids) together to form larger particles (called flocs) that can be settled or filtered out. The colloids are too small to settle out on their own and typically have a negative charge, so they repel each other, and resist clumping together on their own. The coagulant typically has a positive electric charge that neutralizes the charge on the colloids and allows them to stick together.
Colloid - A very small electrically charged particle that will not settle out of the water. Colloids usually have a negative charge and repel each other. This electrical charge helps keep them from settling out on their own. Positively charged coagulants are added during the water treatment process to overcome the negative charge on the colloids so they will stick together and form larger particles that can be settled or filtered out.
Colour, Odour and Taste Problems - Problems with the taste, smell or “look” of the water are called aesthetic issues. They do not necessarily impact human health but can still be a concern. People may think water is not safe to drink if they do not like the way it looks, tastes or smells and they may choose to drink water that looks or tastes better but is not safe. Contaminated water can look clear, and taste cool and refreshing but still make you sick! Properly treated water may or may not look as good, but it is safe to drink. Sometimes, even after the contaminants are removed, treated water can have unpleasant colour, smell or taste. During winter, for example, water reservoirs are covered with ice, the dissolved oxygen content decreases, and the water may end up tasting “flat”. The water is still safe to drink but may not taste as good as water from other untreated sources. People who choose to drink untreated water from other sources may end up getting sick.
Contaminant - In relation to drinking water, a contaminant is any biological, chemical, physical, or radiological substance in the water that can cause human health or aesthetic problems. This includes E. coli, Cryptosporidium, Giardia, iron, manganese and others. Contaminants can be found in any water source.
Cryptosporidium - Is a single-celled parasite that can sometimes be found in lakes and rivers in areas inhabited by wildlife. It is very resistant to chlorine. In 2001, Cryptosporidium contaminated the drinking water in North Battleford, Saskatchewan, leaving 7,000 people sick.
Floc - A clump that looks fluffy.
Flocculation - During flocculation the water is stirred very slowly to allow smaller particles and flocs to bump into each other, stick together and form larger flocs. An additional flocculant or polymer may be added to the water to help form bridges between the smaller flocs and bind them into larger flocs. Once the smaller particles are flocculated into larger particles, they can usually be removed by sedimentation, filtration, straining, or floatation. Flocculation not only increases the size and density of the floc particles to settle them faster, but also affects the physical nature of the floc, making them less gelatinous and thereby easier to settle or filter out.
Fluoridation - The addition of fluoride to the water to help prevent dental cavities
Giardia - Giardia is a protozoan found in lakes and rivers in areas inhabited by wildlife, especially beavers. If you drink water contaminated by giardia, you may get “beaver fever” or giardiasis.
GCDWQ - Guidelines for Canadian Drinking Water Quality. The GCDWQ are set by the Federal-Provincial-Territorial Drinking Water Committee. In the Northwest Territories, the GCDWQ are used to measure the safety of drinking water, and water treatment plants are designed and operated to meet the existing guidelines. The Northwest Territories has a representative on the Federal-Provincial-Territorial Drinking Water Committee.
IMAC - Interim Maximum Acceptable Concentration. The Guidelines for Canadian Drinking Water Quality (GCDWQ) recommend maximum acceptable concentrations (MACs) of contaminants that affect human health. Where the recommended MAC is less than can be reliably measured or achieved by existing water treatment technology, an "interim MAC" is developed and a recommendation is made to improve existing analytical or water treatment methods.
MAC - Maximum Acceptable Concentration. The Guidelines for Canadian Drinking Water Quality (GCDWQ) recommend maximum acceptable concentrations of contaminants that affect human health.
Microfiltreation - A physical process to remove solids greater than 0.1 microns.
Nanofiltration - A physical process to remove solids greater than 0.001 microns.
Potassium Permanganate - A chemical used to oxidize iron and manganise into a solid form that can be filered out.
Pressure Greensand Filter - A pressurized tank that contains greensand and anthracite for removal of oxidized iron and manganese.
Sedimentation - The water treatment process that allows particles in the water to settle out so they can be collected and removed.
Small System - Water treatment plants (WTPs) are classified according to the complexity of the treatment system, the quality of the raw water source, capacity of the system, types and degrees of process controls and instrumentation, chemicals used in the treatment process and the treatment and disposal of waste such as backwash water, sludge and residuals. Small systems are the simplest systems in the NWT (compared to Class 1, 2 and 3 Systems). Most small systems in the NWT where the source water is classified as pristine (filtration is not required as per GCDWQ) typically include a reusable filter to screen out suspended solids that may interfere with the disinfection process, UV disinfection followed by chlorine addition prior to storage and distribution. Other small systems where source water is not classified as pristine may include a series of cartridge filters followed by UV and/or chlorine disinfection prior to storage and distribution.
Softening - A chemical ion-exchange process to remove hardness from water.
Tempering - Heating the water to protect against freezing.
UV Irradiation - UV light disinfection is highly effective for inactivating protozoa (Giardia and Cryptosporidium). The disinfection process uses UV radiation to disrupt the life cycle of microorganisms. The radiation damages the microorganisms’ cells and inhibits reproduction and their ability to infect their hosts. However, due to the nature and properties of UV, it leaves no residual in the water and requires a secondary disinfectant, such as chlorine to provide residual in the distribution system.