Source water
Wells must be a safe distance from pollution sources, have a water-tight casing and be protected overall from contaminants
Preventing drinking water contamination at the source can be accomplished by identifying contaminants of concern and reducing or eliminating them. Water can become contaminated with: biological organisms, such as bacteria, parasites and viruses chemical agents, such as nitrates and lead toxins created by algae in surface water
Types of source water
Secure ground water systems
A secure ground water system is a well system that is designed and maintained in accordance with Regulation 903 – Wells under the Ontario Water Resources Act. Important considerations are that the well is a safe distance from any pollution source, has a water-tight casing to over 6 metres in depth and is otherwise protected from surface water contamination.
A secure groundwater system without treatment may be capable of providing safe water. If no treatment is provided, ensuring the safety of the water is limited to source water protection and routine surveillance activities.
Some tips to prevent contamination of your secure ground water supply:
- Ensure that the well is constructed and maintained in such a way to prevent possible contaminants from entering the well.
- Ensure that potential sources of contamination (for example, septic systems, manure storage or chemical usage) are kept safely away from the well.
- Conduct additional sampling and testing if there is a possible threat to the quality of the well water.
Non-secure ground water systems
A non-secure groundwater system is a well or other groundwater collection system that is not a safe distance from pollution sources or is not designed or constructed to prevent contamination by surface water.
If you get your drinking water from a well, contaminants may enter through cracks in the casing, poorly fitted lids or other structural faults. Private wells can become contaminated with bacteria, nitrates or other chemicals if they are close to sources of pollution.
A non-secure groundwater source will require disinfection, at a minimum, to be used for drinking water. This type of water supply has a greater potential for becoming contaminated. The treatment equipment must be checked and maintained to ensure proper operation.
Some tips to prevent contamination of non-secure ground water supply:
- Ensure that the well is constructed and maintained in a manner that prevents contamination that would require filtration.
- Ensure that the well is protected from any potential source of contamination (for example, septic systems, manure storage or chemical use).
- Ensure that the treatment system is always operating so the water is safe.
- Conduct additional sampling and testing where there is a possible threat to the quality of the well water.
- Maintain a level of surveillance of the source water, surrounding area and treatment system suitable to the complexity of the system by scheduling frequent sampling, testing and routine maintenance checks.
Surface water systems
A surface water system is any system that draws water from surface water or a system that may be contaminated by surface water.
Surface water sources are unsafe for drinking, unless the water is filtered and treated to destroy harmful micro-organisms. A surface water system (which may also include a groundwater system that is contaminated by surface water) requires both filtration to physically remove microbes that are not killed by disinfection and disinfection to kill bacteria and viruses.
Some tips to prevent contamination of a surface water supply:
- Ensure that the treatment system is capable of providing the level of treatment necessary to properly remove micro-organisms and disinfect water.
- Ensure that potential contamination that could overburden the treatment system does not enter the drinking water intake.
- Ensure that the treatment system is always operating so that the water is safe.
- Conduct additional sampling and testing if there is a possible threat to the quality of the well water.
- Maintain a level of surveillance of the source water, surrounding area and treatment system suitable to the complexity of the system by scheduling frequent sampling, testing and routine maintenance checks.
Factors that affect source water quality
Protect the source(s) of drinking water from contamination and overuse to support the provision of safe, clean drinking water.
Preventing drinking water contamination at the source can be accomplished by identifying contaminants of concern and reducing or eliminating them. Potential sources of contamination include:
- rainfall and snow melt
- ground slope towards well
- natural chemical content in soil or rock
- wildlife activity
- agricultural runoff
- pets or farm animal activity
- private sewage disposal systems
- chemical spills or releases
This item was last modified on November 20, 2015