If you are on a private well, nobody else is testing your water. The good news is that the most important test, for bacteria, is free in Ontario. The catch is that it only covers bacteria. Here is how to use it, and what else your well may need.
Why well owners have to test
Municipal water is tested by the municipality and the results are published. A private well is the owner's responsibility. Groundwater can look, smell and taste perfectly clean and still carry bacteria, and it can change with the seasons, with heavy rain, or after work on the well. The only way to know what is in it is to test.
That applies whether you are on a drilled well in East Gwillimbury, King or Whitchurch-Stouffville, or a shallower well in rural Georgina, Bradford, Innisfil or Brock Township.
The free bacteria test
Public Health Ontario tests private well water for bacteria free of charge. You pick up a sample bottle and instructions from your local public health unit or a participating pick-up location, fill it at home, and return it. The Province explains the program on its testing and treating private water wells page.
A few things make the difference between a good sample and a wasted trip:
- Use the bottle provided. It is sterile. Do not rinse it out, and do not touch the inside of the cap or bottle.
- Sample from a cold tap that is not a pull-out or swivel faucet if you have a choice. Remove the aerator and run the water for a few minutes first.
- Sample before any treatment if you want to know what the well is doing, or after it if you want to know whether your treatment is working. Ideally, both.
- Get it back quickly. Bacteria samples have a short time limit. Follow the timing on the instructions and keep the bottle cool on the way.
What the results mean
The test looks for two indicator organisms: total coliforms and E. coli. Total coliforms are a broad group that tells you surface water or soil may be getting into the well. E. coli comes from human or animal waste and is a direct sign of contamination. Health Canada's maximum acceptable concentration for E. coli is none detectable per 100 mL (see the Guidelines for Canadian Drinking Water Quality summary table). Total coliforms are an indicator, and Public Health Ontario reports your result in one of these groups:
- No significant evidence of bacterial contamination: E. coli 0 and total coliforms 5 or fewer per 100 mL.
- Significant evidence of bacterial contamination: E. coli 0 and total coliforms more than 5. The water may be unsafe to drink; disinfect the well and retest.
- E. coli detected: 1 or more E. coli per 100 mL. The water is unsafe to drink.
- Overgrown sample (NDOGN or NDOGT): too many bacteria to count. Treat the water as unsafe and resample.
If E. coli is found, do not drink the water. Use bottled or properly boiled water, follow the advice that comes with your result, and contact your local public health unit. The usual next steps are to inspect the well cap and casing, shock chlorinate the well, and retest. If contamination keeps coming back, UV disinfection gives you a permanent barrier at the point of entry.
What the free test does not cover
This is the part most people miss. The free test checks for bacteria only. A clean result does not mean the water has nothing else in it. The Province notes that chemical concerns need a licensed laboratory, and those tests are not free. Common things a bacteria test will not tell you about:
- Nitrates, from fertilizer, manure and septic systems, which matter most for infants.
- Iron and manganese, the source of orange and black staining.
- Hydrogen sulphide, the rotten-egg smell.
- Hardness, pH and dissolved solids, which decide scale and how treatment equipment performs.
- Sodium, chloride and other dissolved minerals, including road salt near busy roads.
- Naturally occurring metals and other chemicals that vary by location and depth.
Our in-depth well water testing fills in the rest. Hardness, iron, manganese, hydrogen sulphide, pH and dissolved solids we read at your kitchen table. Nitrates, sodium, metals and anything else that needs a chemical lab panel go through an Ontario laboratory, and we explain the results in plain language.
When to test your well
The Province recommends testing regularly so you build up a baseline and can see how much your water changes, and testing more often around unusual events such as the spring melt. On top of a regular routine, test:
- After heavy rain, flooding or a spring melt that pools water near the wellhead.
- After any work on the well, the pump or the plumbing.
- When the water changes colour, taste, smell or clarity.
- When buying or selling a home on a well.
- When someone in the home is pregnant or a new baby arrives.
- Before choosing treatment equipment, so it is sized to real numbers.
From results to a fix
Once you know what is in the water, the order of treatment follows. Sediment filtration first, then an iron and sulphur filter if staining or smell is the problem, then a softener for hardness, then UV last as the disinfection barrier. Our well water treatment page walks through how those stages fit together, and our article on iron and sulphur in well water goes deeper on the two most common complaints.
Common questions
Is well water testing free in Ontario?
Bacteria testing is. Public Health Ontario tests private well water for total coliforms and E. coli at no charge, using bottles from your local public health unit. Chemical testing through a licensed lab is not free.
How often should I test my well water?
Regularly, so you have a baseline to compare against, and more often around the spring melt, after heavy rain or flooding, after work on the well, and whenever the water changes. Your local public health unit can advise on a routine for your well.
What does the free well water test check for?
Two indicator bacteria: total coliforms and E. coli. It does not test for nitrates, iron, manganese, sulphur, hardness, sodium, metals or other chemicals.
What should I do if my well tests positive for E. coli?
Stop drinking the water, use bottled or boiled water, and contact your local public health unit for advice. Then look for the cause, disinfect the well, and retest before going back to drinking it.
How do I read my well water test results in Ontario?
Look at the E. coli and total coliform counts. Any E. coli means the water is unsafe to drink. More than 5 total coliforms per 100 mL means significant bacterial contamination, so disinfect the well and retest. An overgrown result means resample. We can walk you through your report as part of our in-depth well water testing.
Can I use a home test kit instead?
Store-bought strips can give a rough idea of hardness or pH, but they are not a substitute for a lab bacteria test. Use the free public health test for bacteria and a proper on-site or lab test for everything else.
Does a new or newly drilled well need testing?
Yes. Test once the well has been disinfected and flushed after drilling, and before anyone drinks from it. It is also the best time to run a full chemical panel so your treatment is designed around real numbers.