Private Wells

There are over 50,000 private wells in the Ottawa area. Well owners are responsible for ensuring that water from their wells is safe to drink, and that their wells are not contaminating the groundwater. Wells must be properly designed and maintained to ensure that drinking water is safe.

Common types of wells: Dug and bored wells (with casings 60 to 120 cm/24 to 48 in.) are less expensive to install than drilled wells. Like sand point wells, dug/bored wells are prone to near-surface contamination and shortages. Drilled wells (casings 10 to 20 cm/4 to 8 in.) cost more but penetrate deeper aquifers.

Drilled wells

A drilled well consists of a small-diameter casing ranging in size from 10 to 20 cm (4 to 8 in.). 

Drilled wells obtain water from either overburden or bedrock aquifers. Overburden wells include those constructed into overburden aquifers (the geological materials above bedrock), composed typically of sands and gravels, but also possibly of silts and clays.

A properly constructed and maintained drilled well should prevent the entry of any foreign substance into the well casing that might impair water quality.

Dug wells

Dug wells are constructed with prefabricated concrete tile or corrugated galvanized steel pipe ranging in diameter from 60 to 120 cm (24 to 48 in). Older wells may be constructed of brick, stone or even wood cribbing and are very susceptible to undesirable surface-water seepage through the portion of the casing located above the water table. Dug wells, which were often hand-dug in the past, are now constructed primarily with excavation equipment and are usually no more than 9 m (30 ft) deep.

Sand point wells

Sand point well point or driven-point wells consist of a small-diameter casing ranging in size from 2.5 to 5 cm (1 to 2 inches). Well points are constructed in sand and gravel aquifers and are either driven or jetted (inserted using high-pressure water) into the ground. Well points are usually only installed where the aquifer has a shallow water table and contains few or no stones. 

Visit the Ministry of Agriculture, Food and Agribusiness web page to learn more about different types of private rural water wells.

Is it clean? When an aquifer gets contaminated, the water may be unfit and unsafe to use. Groundwater can become contaminated in several ways:

• spills on the ground, such as fuel and pesticide spills
• injection into the ground, such as septic leaching beds, disposal of waste in wells, contaminated surface water running into poorly constructed or maintained wells
• improper handling of industrial solvents and chemicals
• waste leakage, such as manure storage, wastewater, septic tanks and landfills
• leaking underground and above-ground fuel storage tanks
• groundwater travelling from contaminated to clean aquifers
• over-application of manure, commercial fertilizers or pesticides

Whether the groundwater gets 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 

Your well water can be contaminated by:

• openings in the well seal
• improperly installed well casing
• well casing not deep enough
• well casing not sealed
• a source of contamination not related to well construction (e.g. your septic system, pet waste or livestock waste, agricultural or road chemicals)

You can prevent contamination by:

• do not allow liquids or wastes from garbage and manure piles to drain towards the well casing
• do not locate dog runs around the well casing
• do not treat the area around the well with pesticides or fertilizer
• do not flush oils, detergents, paints, solvents or other chemicals down the toilet

Proper installation and maintenance includes ensuring the:

• sanitary seal or well cap is securely in place and watertight
• cap is at least 30 cm above the ground
• joints, cracks and connections in the well casing are sealed
• surface drainage near the well is directed away from the well casing
• surface water does not pond near the well
• well pump and distribution systems are checked regularly
• changes in the quantity and quality of water are investigated immediately
• well water is tested for bacteria three times a year and after major plumbing work
• wells are chlorinated and tested after any major repairs

Abandoned wells should be carefully sealed to prevent pollution of groundwater and any safety hazards. Hiring a qualified well contractor to seal the well is strongly recommended. 

Power outages can disrupt private well water drinking supplies.

A power outage will normally cause the well water pump to fail. In this situation you should use an alternate source of safe water, such as commercially bottled water or follow the instructions provided here for temporarily treating your water.

If you have a back-up generator supplying power to your well pump you can use the water as usual. 

To treat water for drinking or making infant formula, juices, ice, or recipes; brushing your teeth; and washing food or dishes:

• Bring it to a rolling boil for at least one minute and let it cool before using.

Or

• Disinfect one litre of water with household bleach (containing about 5.25% chlorine) with two drops (0.1 mL) of household bleach. If your water is cloudy use four drops of household bleach per one litre of water.
• Stir it well and let it stand for at least 30 minutes before you use it.

Store boiled or disinfected water in clean containers with covers. Refrigerate if possible.

After power is restored

• If you have a back-up generator, continue to use the water as you did before the power failure.   
• If you lost power and it is now restored: 
  • Before drinking the water, flush all lines by letting the water run for five minutes at each tap. 
  • Test your well water for bacterial water quality before you use it if your water system lost all its pressure, and no water came out of the faucets during a power outage. See the OPH website Free Well Water Testing for information on how to test your well.
• If you have a concern about your water quality, continue to use a safe water source until you have tested it and confirmed it is safe to drink. Use an alternate source of safe water, such as commercially bottled water.
  or
  • Bring it to a rolling boil for at least one minute and let it cool before using, or
  • Disinfect one litre of water with household bleach (containing about 5.25% chlorine) with two drops (0.1 mL) of household bleach. If your water is cloudy use four drops of household bleach per one litre of water.
  • Stir it well and let it stand for at least 30 minutes before you use it.
• If you have a private treatment system for your drinking water, such as ultraviolet light, make sure the treatment system is running properly once the power is restored.  

Is your well producing less water?

A well is considered “dry” when the groundwater table falls below the bottom of the well and no more water can be drawn. Signs your well may be struggling include discolored water, sediment, or reduced water flow. If neighboring wells are experiencing problems, yours could be at risk too. Other factors such as mechanical issues, pump problems, or overuse of the aquifer can also reduce water supply. Long periods of dry weather and climate change can further limit groundwater recharge, lowering available water levels.

What can you do?

As a well owner, it’s your responsibility to manage and protect your well. Preparing for potential water shortages is important and may include:

• Practicing water conservation year-round.
• Installing water storage systems.
• Exploring safe alternative water sources.
• Monitoring your well’s performance.

Conserving water before a drought begins helps build resilience. Staying informed about local drought conditions and water use restrictions can also guide your conservation practices. Check the status of drought conditions in your watershed by visiting the following local conservation authorities’ websites:

• Cataraqui Conservation Authority
• Mississippi Valley Conservation Authority
• Rideau Valley Conservation Authority
• South Nation Conservation Authority 

Drought readiness and planning

To better prepare your system for times of low water:

• Conserve water regularly: Use efficient appliances, avoid waste, and adopt water-smart landscaping.
• Respect local watering restrictions: These support both community and groundwater protection.
• Add storage capacity: Cisterns or tanks can hold water for later use. When storing potable water, ensure proper treatment.
• Collect rainwater: Suitable for non-drinking uses like gardens or cleaning (rainwater requires treatment before use as drinking water).
• Schedule maintenance: Regular servicing by a licensed well driller or pump installer helps prevent issues and ensures your well is in good condition.
• Work with neighbors: Groundwater is shared—coordinating water use can help avoid shortages.

Why wells stop producing water

Possible causes include:

1. Overuse or pumping faster than the well can recover.
2. Blocked well screens or fractures.
3. Drought or low water table.
4. Pump not set deep enough or well too shallow.
5. Equipment requiring maintenance.
6. Leaks in the system wasting water.

What to do if your well runs dry

If you suspect your well is running low or dry (For example, cloudy water, sediment, or no flow):

• Contact a licensed well driller, pump installer, or groundwater specialist to assess the problem.
• Consider water storage solutions (such as cisterns filled with trucked potable water from an approved source).
• Collaborate with neighbors on water-use scheduling.
• Develop a long-term plan for drought resilience.

Private well owners are encouraged to continue testing their well water, especially during dry conditions when water levels are low and the risk of contamination may increase. If your well runs dry, use a safe alternative water source until the well recharges and water can be tested again. Public Health Ontario Laboratories test private well water for free.

Learn more about free well water testing for bacteria.

What not to do

• Do not pour water into your well (including trucked water or rainwater). This can damage the well, alter water chemistry, and contaminate the aquifer.
• Do not open your well or lower objects into it—this increases the risk of contamination.
• Do not attempt your own repairs. Only trained and licensed professionals should service wells.

Monitoring water levels in your well

Keeping track of water levels can help you understand your well’s capacity and manage usage. Monitoring can:

• Show the impact of pumping on your water supply.
• Reveal seasonal changes, including the effects of drought and rainfall.
• Help detect leaks or inefficiencies in your system.

To start monitoring, consult a licensed professional to select and install appropriate equipment.

Online resources

• Ministry of the Environment, Conservation and Parks web page

Public Health Ontario provides testing for E. coli and total coliforms for private well owners. For all other environmental testing, including sodium and nitrate, private well owners must contact a private lab.

Sodium

Are you on a salt restricted diet for a medical condition such as very high blood pressure or congestive heart failure? Do you have a baby that requires salt restriction that you are feeding with powdered formula made from your private well water?

If you have one of the above medical conditions, it is important to speak with your physician to determine whether you need to an alternative drinking water source.

You should be aware of the amount of sodium in your drinking water - the advisory level for sodium in drinking water is 20 mg/L (milligrams per litre). This advisory level is for people on sodium-restricted diets. Typically one can taste sodium at 130 to 140 mg/L, and when it exceeds 200 mg/L, water tastes salty. Keep in mind that there are many other sources of sodium - such as processed foods and, in some homes, water softeners—that are usually much larger contributors to your daily sodium intake such as processed foods.  The amount of sodium in City of Ottawa supplied water from the Ottawa River is low (18 mg/L) and would not be a health concern to people on sodium-restricted diets. However, well water usually has a higher sodium content than river or lake water.  

If your water is supplied from one of Ottawa’s municipal well systems (Carp, Kings Park, Munster, Shadow Ridge, Vars, Richmond West) the sodium levels are as follows (original data from Drinking water - City of Ottawa):

If you have your own private well, you should consider testing your water for sodium at least once every 5 years.  As well, it is highly recommended to have your water tested for nitrates (important for babies receiving formula made with water from your private well). Contact a private lab that tests drinking water for sodium and nitrates.

Do you have a water softener? Water softeners can substantially increase the level of sodium in drinking water. Use a separate, soft water supply (one that by-passes the water softening equipment) for drinking and cooking purposes as some foods already have a high sodium content.  

Nitrate

What is nitrate?

Nitrate is a form of nitrogen that is found naturally in groundwater and in plants such as fruits and vegetables.  Other sources include fertilizers, industrial waste water and septic system leaks.

How do nitrates get into drinking water?

Nitrates can get into groundwater and into your well water through many sources, including: surface runoff from agricultural activities like fertilizer use from farming or animal manure, into a poorly constructed or damaged well; leaking septic systems; and the natural decay of organic matter in groundwater. Elevated concentrations of nitrate in groundwater are often localized and due to human activities. This means that you could have high nitrate in your water even if your neighbour does not.

What are the health effects of nitrate in drinking water?

For most Ontario residents, the primary source of nitrate exposure is through food, followed by drinking water. Consuming high levels of dietary nitrates can be harmful especially for infants under six months of age. Exposure to high concentrations of nitrate can cause a condition called methemoglobinemia also known as blue-baby syndrome. Methemoglobinemia interferes with oxygen delivery to cells in the body. The most obvious symptom is bluish skin colour, particularly around the eyes and mouth.

There is also some evidence linking nitrate exposure to adverse pregnancy outcomes; pregnant women can also be considered a special risk group.

How do I know if I have nitrate in my drinking water?

Nitrates are tasteless, odourless and colourless. Municipal drinking water systems are tested regularly but the only way to know if there are nitrates in your private well water is to have it tested by a licensed laboratory. 

You should test your private well for nitrate:

• At least twice initially – once in the spring and once in the fall because concentrations will vary with weather and the season
• More frequently if nitrate levels are near the drinking water standard or if you have a dug well (less than 6 m deep)
• If your well always shows no signs of nitrate, you can test less often (every 2 to 3 years)
• If you have a treatment system to remove nitrate from your water, test the treated water annually to ensure it is working properly. 

How much nitrate is allowed in drinking water?

The maximum acceptable concentration for nitrate (as nitrogen) in drinking water in Ontario is 10 mg/L. This amount is set to be protective of the health of the most vulnerable subpopulation, formula fed infants.

What should I do if I have nitrates in my drinking water?

You are responsible for ensuring your well water is safe to drink.  If your well water has levels of nitrate above the Ontario standard and there is an infant (under 6 months) or a pregnant woman in the home, you should use another source of water for drinking and preparing food (including formula). Boiling water will not reduce or remove nitrate. Other steps you could take include:

• Seek advice from a licensed well contractor or a licensed groundwater consultant to ensure your well is properly constructed and maintained to minimize the risk of contamination;
• Identify potential sources of nitrate contamination, such as fertilizers, septic systems, and manure, around your property and reduce the risk of nitrates entering your well;
• Remove or reduce potential sources of nitrate near the well;
• Consider options for a long-term safe water supply, such as obtaining water from a public (municipal) water system or installing a water treatment system. For treatment options, you should consult with a water treatment professional;
• Regularly inspect your well and test your well water. Hire a licensed well contractor if needed.

Bottled water

While bottled water available in Canada is generally of good quality, it is not necessarily safer or healthier than water from municipal supplies.

The sale of bottled water is not licensed in Canada. However, the federal Health Protection Branch makes spot checks from time to time of both domestic and foreign bottled water. In addition, local health units do regular bacterial testing on all bottled water distribution located in their district.

Municipal water supplies are checked for 350 or more substances. Only three substances must be checked in bottled water. These are bacteria content, fluoride and total dissolved solids (magnesium, iron, sodium).

Bottled water may contain naturally occurring bacteria, which under improper and/or prolonged storage conditions, could increase in numbers to levels that may be harmful to health. Refrigeration is a good way to reduce the growth of these bacteria.

Storage of bottled water may provide an opportunity for bacteria to grow, particularly if the containers were not sterile.

Water from cisterns

The water in cisterns usually comes from rainfall collected off the roof. It is stored in concrete tanks (reservoirs) in the basement or attic.

The water collected can be contaminated from many sources (especially bird droppings) and thus is not safe for drinking.

If a cistern supply exists or is planned, it is recommended that no connections be made between the main water supply and the cistern. Colour coding of the water pipes is also a good idea to ensure that a separation exists.

The use of a cistern supply is not recommended for human bathing or drinking water. Cistern water should only be used for such uses as lawn and garden watering and washing cars.

East Ottawa – Champlain Groundwater Study