When you buy a home on a private well, you are buying the water supply along with the house. No municipality tests it and no utility fixes it. The time to find out what it delivers is before you close, while you still have leverage and options. Here is what to test, how to do it, and how to read the paperwork.
Why the seller's old result is not enough
Sellers often hand over a bacteria result, sometimes from a few months ago, sometimes from years back. It is worth having, but it tells you about one bottle on one day. Well water changes with the seasons, with heavy rain and snowmelt, and after any work on the well or the pump. A clean result from a dry summer says little about the same well after a wet spring.
There is also the question of who took the sample and where. A sample drawn after a softener, a UV unit or a filter shows what the treatment is doing, not what the well is doing. A sample from a tap that was not run first, or a bottle that sat in a warm car, can give a result that does not reflect the water at all. You do not have to assume anything was done wrong. You only have to recognise that a result you did not see collected is not a result you can lean on for one of the largest purchases you will make.
The better approach is simple: make fresh testing part of the deal. Talk to your real estate lawyer and agent about writing water testing into the offer as a condition, so a bad result gives you room to negotiate, ask for repairs, or walk away. Ask the seller for access to the well and the water system so the sample is taken on your terms.
The free bacteria test for private wells
Ontario offers free bacteria testing of private well water through Public Health Ontario. You pick up a sterile sample bottle and instructions from your local public health unit, or a participating pick-up location, fill it at the house, and return it within the time limit on the instructions. The Province describes the program on its testing and treating private water wells page.
The test looks for total coliforms and E. coli. Health Canada's maximum acceptable concentration for E. coli is none detectable per 100 mL, and Public Health Ontario treats more than 5 total coliforms per 100 mL as significant evidence of contamination (see Public Health Ontario well water testing). Total coliforms suggest surface water or soil may be getting into the well. E. coli is a direct sign of contamination from human or animal waste.
For a purchase, a few points matter more than usual:
- Sample before any treatment if you can, so you see the raw well. If the house has UV or a filter, a second sample after the treatment shows whether that equipment is doing its job.
- Remove the aerator and run the cold tap for a few minutes before filling the bottle. Do not rinse the bottle or touch the inside of the cap.
- Think about more than one sample. Two results taken some days apart tell you far more than one, and leave less room for a lucky day.
- Allow for timing. Build enough days into the condition period to collect, deliver and get results back, and to retest if needed.
Our guide on how to test your well water in Ontario goes through the sampling steps in more detail.
What a lab panel adds
The free test covers bacteria only. A clean bacteria result does not tell you whether the water stains, smells, scales or carries something you would rather not drink. Those questions need a chemical analysis, and the Province notes that chemical testing goes through a licensed laboratory at the owner's cost. For a home purchase, these are the results worth having:
- Nitrates, from fertilizer, manure and septic systems. They matter most for infants and during pregnancy, and they are common in farm country.
- Iron, which causes orange and brown staining on fixtures and laundry.
- Manganese, which causes black staining and has a health-based limit as well as an aesthetic one.
- Sulphide, the rotten-egg smell, which also tarnishes and corrodes.
- Hardness, which decides whether you will be fighting scale in the water heater, dishwasher and fixtures.
- Sodium, which matters for anyone on a sodium-restricted diet and can point to road salt reaching the well.
Our in-depth well water testing fills in the rest. It covers hardness, iron, manganese, hydrogen sulphide, pH and dissolved solids at the kitchen sink, which gives you a quick read on what treatment the house will need. Where you need certified lab results for nitrates, sodium or anything else, we will tell you what to ask the lab for and help you make sense of the report when it comes back.
Reading the well record and checking the cap and casing
Ask the seller for everything they have on the well: the well record from when it was drilled, any repair or pump invoices, past water results, and the manuals for any treatment equipment. In Ontario, the well contractor who constructs a well files a record with the Ministry of the Environment, Conservation and Parks, and the record usually shows the depth, the type of well, and what the driller found on the way down.
Depth and type tell you a lot. A deep drilled well draws from further below the surface and is generally better protected. A shallow dug or bored well is more exposed to surface water, runoff and nearby septic systems, and deserves closer attention in the bacteria results.
Then look at the wellhead itself. The things to check:
- The casing should stick up above the ground, not sit flush with the lawn or in a pit where water collects.
- The cap should be secure, vermin-proof and intact, with no gaps, cracks or missing screws.
- The ground around it should slope away from the well so rain and snowmelt do not pool at the casing.
- Nearby hazards such as the septic bed, a driveway that gets salted, a fuel tank or a livestock area should be well away from the wellhead.
A home inspector may note some of this, but a well contractor licensed in Ontario can inspect the well properly if anything looks wrong. Many of the contamination problems we see trace back to a damaged cap or a buried casing, and those are among the cheaper things to put right.
What to do if a result fails before closing
A failed result is information, not necessarily the end of the deal. What you do next depends on what failed.
If E. coli or total coliforms are found, nobody should drink the water until the problem is dealt with. Follow the advice that comes with the result and contact your local public health unit. The usual sequence is to find the cause, repair the cap or casing if needed, shock chlorinate the well, flush it, and retest. If bacteria keep coming back, UV disinfection gives the house a permanent barrier at the point of entry.
If iron, manganese, sulphide or hardness come back high, the water is treatable. These are some of the most common results on wells in our area, and a properly sized system handles them. Our well water treatment page explains the usual order: sediment, then an iron and sulphur filter, then a softener, then UV.
If nitrates or sodium are the problem, reverse osmosis at the kitchen tap is the usual answer for the water you drink and cook with. It is worth confirming the source too, because nitrates often point to a septic system or field too close to the well.
In each case, get the finding in writing, talk to your lawyer about how it affects your condition, and get a treatment recommendation based on the actual numbers so you know what you are taking on before the deal closes.
Around northern York Region
Many homes for sale in rural Georgina, East Gwillimbury and King are on wells, because municipal water does not reach them. If you are buying in one of those areas, book in-depth well water testing during your condition period and you will know what the water needs before you sign.
Common questions
Should I make my offer conditional on a water test?
For a home on a private well, it is common and sensible. Ask your real estate lawyer to word the condition, and leave enough days to collect samples, get results back and retest if needed.
Is the seller's water test good enough?
It is useful background, but it is one sample on one day, and you did not see how it was taken. A fresh bacteria test you arrange yourself, ideally two samples a few days apart, is the result to rely on.
Who pays for well water testing when buying a house?
The bacteria test through Public Health Ontario is free for private well water, whether you own the home or are buying it, so the buyer can arrange it directly. Chemical testing for nitrates, sodium and similar through a licensed lab is not free and is usually paid by whoever orders it. Our guide on how to test well water in Ontario covers the steps.
What should a well water test include for a home purchase?
At minimum, total coliforms and E. coli. For a full picture, add nitrates, iron, manganese, sulphide, hardness and sodium. That combination tells you whether the water is safe and what it will take to make it pleasant to use.
Can a failed well test be fixed before closing?
Often. A bacteria problem from a damaged cap may clear after a repair, shock chlorination and a clean retest. Iron, hardness and sulphur are fixed with treatment equipment. Your lawyer can advise on how to handle repairs or credits within the deal.
How do I find the well record for a property?
Ask the seller first. Well records are filed with the Ministry of the Environment, Conservation and Parks when a well is constructed, so the seller, a previous owner or the ministry may be able to provide it.