FAQ - Private Water Supplies

General Information

What percentage of Canadians rely on private water supplies?
An estimated 25% percent of Canadians, living primarily in rural areas, rely on private wells, cisterns or other sources for their drinking water. It must be emphasized that these individuals have the sole responsibility for ensuring the safety of their water supply. The most important concern for safe water in these systems is microbiological safety since the presence of a microbiological risk can and will have an immediate acute effect on those who consume the water. Chemical contamination problems do occur and frequently while of concern, the condition is not normally of an acute health concern. Exceptions may be when there is a chemical transport accident in the vicinity, or there is or has been excessive or inappropriate use of fertilizers or pesticides.

Back to top

Maintaining Your Well

What can be done to protect the quality of well water?
Action for ensuring the microbiological safety of well water is paramount and comes down to frequent testing and adequate well-head protection. It is recommended that water be tested regularly for bacteriological quality, and be further tested for chemical contamination if that is suspected. Any changes in clarity, colour, odour or taste can indicate chemical contamination, and tests should be carried out if this occurs. Depending on the province, bacteriological testing of well water is done either by the provincial health laboratory or by certified private laboratories, but at the owners expenses. All new wells are required to be tested, retesting is left up to the owner. Tests for chemical contamination are normally referred to private laboratories, although some provinces will analyze water for nitrates. The Environmental Health Division of the local Health Unit is able to supply information on possible contaminants which are known to be found in local wells or water supplies, and will help interpret results of chemical and bacteriological tests.
How do wells become contaminated?
Groundwater can become contaminated in several ways:
Geologic formations may remove some contaminants. For example, metals like lead and mercury can become attached to soil particles. Nitrate levels can be reduced in the aquifer through denitrification.
The likelihood that groundwater could become contaminated depends on: the size or strength of the contamination source; the ease with which the contaminant can move into or travel through the soil Contaminants move most easily through coarse-textured soils (sand and gravel) and fractured bedrock. But even clay soils can have fractures that allow the movement of contaminants. Once contaminants have reached an aquifer, they are difficult and expensive to remove. High levels of a contaminant in an aquifer can make the water unfit and unsafe to use.
Where can I get more information on groundwater and well testing in my province?
The provinces have labs to which you can take water to be tested for more information on this service in your province. Follow the hyperlink for groundwater testing information in your province:
What do I do if my water tests positive for microbiological contamination?
Well water should be tested regularly for bacterial contamination and laboratories will measure both the total coliform levels and test for E.coli. The presence of coliform could indicate that the water has been contaminated by fecal matter. The presence of E. coli indicates that water is contaminated by fecal matter. Drinking water should contain no more than 10 total coliform bacteria per 100 mL of water, and absolutely no E.coli. If well water exceeds these parameters the water should be "shock treated," and if possible the source of the contamination found and eliminated. Shock treatment involves adding normal unscented household bleach to the well water, the amount of bleach added depends on the depth and diameter of the well. In some cases this treatment may be sufficient to eliminate the problem. However, if it does not, a disinfection device can be installed. A disinfection device should not be used as a replacement for a safe water supply. If the water supply is chronically contaminated by fecal material, a new water supply must be found. Disinfection devices are not commonly used by well owners - most assume, once the well has been approved for use that their water will remain safe.

Back to top

Water Treatment Units

What disinfection devices areavailable for private water supplies?
These fall into two types: those that use chemical disinfectants and those which use Ultra Violet (UV) light. They are most important for persons being supplied from rural private well systems.
Chemical disinfection devices introduce disinfectant chemicals into the incoming water. Ideally this should take place before any storage tank system, so as to provide a residency time that allows the disinfectant to work. The disadvantage of this system is that it will also introduces an odour and taste effect to the water, which some consumers find objectionable. These devices may have control systems on them that can shut down the water supply system if the chemical source has been exhausted and the disinfection process stopped. There are two principal chemical disinfectants chlorination and ozonation.
What is chlorination and how does it work?
Chlorination destroys disease-causing bacteria, nuisance bacteria, parasites and other organisms. It also removes soluble iron, manganese and hydrogen sulfide from water. One of the main advantages to chlorination is that it is a proven technology, and chlorine provides residual protection which can protect against re contamination. Devices which continuously chlorinate a home’s water supply are available, these use an injector to introduce chlorine into the system, water must be in contact with chlorine for 15 minutes to completely kill all bacteria Chlorine must be maintained at a level at which it can be tasted in water to ensure disinfection. Further treatment is often undergone in order to remove particulate matter and to de-chlorinate the water immediately before drinking using carbon filters to remove the taste and odour effects.
What is ozonation and how does it work?
In these units ozone is produced by a generator and pumped through the water to be treated, it oxidizes contaminants and is effective in removing bacteria and microorganisms. Ozone units may also remove other contaminants like organic pesticides. Additional filtration is needed to remove parasites and particulate matter. It offers some residual protection against re-contamination, but this effect is short-lived. This technology is easy to install and maintain. However, it can be expensive, and the unit must be properly maintained to shield against excess ozone escaping, and to maintain the necessary mixing ratio of ozone to water.
What is ultraviolet disinfection and how does it work
Ultraviolet light treatment uses ultraviolet light to disinfect water or reduce the amount of heterotrophic (non-harmful) bacteria. This method uses no chemicals, and produces no taste or odour. It takes only a few seconds of exposure to disinfect the water, is easy to install and relatively inexpensive. However, it is effective in ensuring only the microbiological safety of the water, and further treatment is needed to remove any parasites and other contaminants. The device is installed so that water passes around the UV light which is illuminated only when the water is flowing through the system. A high intensity light disinfects the water as it passes around the light source. If the water is not clear, the turbidity or dissolved solids in the water may form on the surface of the UV light source, slowly diminishing the effectiveness of the process. Again, modern devices have a fail safe, shut off switch which prevents water from flowing through a non-functioning device. The advantage of UV light systems is that they do not affect the taste or odour of the water, although they are more costly to purchase and operate.
How can I treat the taste odour or appearance of my water?
The appearance, taste and smell of drinking water is usually more obvious to the consumer than the bacterial quality. Chemicals such as iron, manganese, calcium hardness and sulphide, often common in private water supplies, can impart disagreeable taste and odours. These problems pose no threat to human health, and the water is safe to drink without further treatment, however, there are devices available to correct these problems, but they do not disinfect, and in some cases can accumulate any existing bacterial contamination. Below are specific devices commonly used in rural settings. These treatment devices should only be used in water that is already microbiologically secure. Before any treatment device is purchased, the water should be tested, to ensure that the best and most economic treatment is selected.
What is hard water and how do you treat it?
Groundwater dissolves rocks and minerals releasing calcium and magnesium ions that cause water to be hard. Hard water can leave scales or deposits in kettles and water heaters and inhibits the performance of soaps, shampoo and detergents. Softening water makes it more suitable for washing and prevents deposits in appliances and pipes. Water softeners work by exchanging the unwanted calcium ions with sodium or potassium and do so using special resins. All softeners need to be recharged on a regular basis (depending on their capacity and the volume of water softened. The recharge water is discharged into the sewer line if it is attached to municipal supply system or into a sceptic tank if attached to a well water supply. The water produced with a sodium exchange system is not generally recommended for drinking or cooking due to its increased sodium content. Both the sodium and the potassium softeners decrease essential mineral content and have the potential of bacterial growth. Softened water is also not recommended for watering house plants, lawns and gardens due to its sodium or potassium content. Wastewater from the softener recharging cycle is not believed to overload or reduce the effectiveness of small septic systems, but there have been examples of the leachate re-entering the groundwater source for the well, thus increasing the sodium and calcium content of the source water. Sodium free water conditioners are available that claim to remove calcium by either catalytic bars or magnetic means. However the effectiveness of either of these methods is questionable and it is the position of the Canadian Water Quality Association (CWQA) that they do not work.

Back to top

Well Drilling

Who governs well drilling?
Most provinces and territories have regulations governing the construction of water wells. Such regulations set out minimum construction standards for all types. The main purpose of the standards is to keep surface water and foreign matter out of wells and aquifers. Regulations cover:
Location plays an important role when planning a new well or upgrading an existing one. Well locations need to meet the minimum separation distances specified by your local provincial or state regulations. Greater separation distances should be allowed wherever possible. Most provinces have regulations that make requirements regarding the minimum separation distance between wells and potential contamination sources. For specific requirements in your province search the legislation database.

Back to top