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Well Water Testing in Ontario (2026): The Free Bacteria Test, What the Results Mean, the Lab Chemistry Worth Paying For, and Shock Chlorination
Plumbing & Water
Well Water Testing: The Free Test Answers One Question, and You Have About Six
Ontario will test your well water for free, and you should take the province up on it at least three times a year. But the free test looks for bacteria and nothing else. It will not tell you about arsenic, nitrate, iron, hardness or the rotten egg smell in the shower. This page covers how to take a sample that means something, how to read the result, which chemistry is worth paying a lab for, when a well gets shocked, and what to test before you buy a house on one.
The numbers
$0Public Health Ontario bacteria test
48 hoursfrom filling the bottle to the lab
3 a yearthe minimum, spring and fall included
about $100 to $400chemistry at a licensed private lab
| Test | Cost | Note |
|---|---|---|
| Total coliform and E. coli, Public Health Ontario | free | bottle from the health unit or a pickup point |
| Chemistry package, licensed private lab | about $100 to $400 | depends on what is on the list; ask the lab |
| Chemistry test, Cottage Life figure | about $200 | plus shipping |
| Well inspection plus water test, before you buy | $300 to $600 | a Canadian cost guide |
| Shock chlorination by a well contractor | quoted per job | casing size, depth of water, travel |
October 2026 prices, before HST. No published Ontario price for having a contractor shock a well turned up, so we do not print one.
Why Ontario prices are all over the map: the labs, dealers and price guides we checked for this page put very different numbers on what sounds like one test. Ontario water treatment dealers and a Barrie well and pump company said $100 to $400 for chemistry. Cottage Life said about $200 plus shipping. A Canadian cost guide said $300 to $600, with a well inspection bundled in. The gap is the list: hardness, iron and nitrate is one price, add metals, arsenic and uranium and it climbs. Budget about $250 for a good package, and get two or three labs to quote the same written list of tests.
Take the Sample Like You Mean It
The free bottle comes from your public health unit or one of its pickup points, with a form. People wreck the test with a dirty tap, a warm bottle left in the truck all weekend, or a sample that misses the lab window.
- Mind the clock. The bottle must reach the lab within 48 hours of collection. In Simcoe Muskoka the drop-off is Monday to Thursday before 4:30 p.m., and there is none on Fridays, so a Friday sample is a Monday re-do.
- Use a cold tap the family drinks from. Not the hose bib, not the laundry tub. Take the aerator off and let the water run a few minutes so you are testing the well, not the faucet.
- Do not touch the inside of the bottle or the cap. Fill it to the line, cap it, keep it cool and get it moving.
- Fill in the whole form. The results come back through Public Health Ontario’s online portal, usually in 2 to 4 business days, and the form is how they find you.
- If you have treatment, know where you sampled. After the UV tells you what you drink; before it tells you what the well is doing.
What the Results Mean
| Result | What it means | What to do |
|---|---|---|
| Total coliform 5 or less, E. coli 0 | No significant evidence of bacterial contamination | Keep testing on schedule |
| Total coliform more than 5, E. coli 0 | Significant evidence of bacterial contamination | Find the cause, usually shock the well, retest; ask the health unit |
| E. coli 1 or more | Unsafe to drink | Do not drink it: boil it or use another source |
| Overgrown | Too much growth to count | Treat as unsafe and resample |
Total coliforms live in soil and surface water, so a high count says the surface is getting in: a loose cap, a cracked casing, water pooling at the well. E. coli lives in the gut of people and animals. In a well it means sewage or manure.
With E. coli, the water is not for drinking, cooking, brushing teeth or baby formula until the well is fixed and two clean tests in a row come back. One good test after a bad one is a coin toss, not an all-clear.
What the Free Test Does Not Tell You
Public Health Ontario tests for total coliforms and E. coli only. Chemistry goes to a licensed private lab, for a fee. These are the numbers worth knowing when the report comes back, from Health Canada’s guideline summary table (December 2025) and the Ontario objectives:
| Substance | Guideline | Why you care |
|---|---|---|
| Arsenic | 0.010 mg/L | health; no taste, no colour |
| Lead | 0.005 mg/L | health; usually the plumbing, not the well |
| Nitrate | 10 mg/L as N (45 as nitrate) | health; never for infant formula above it |
| Uranium | 0.02 mg/L | health; some rock formations carry it |
| Fluoride | 1.5 mg/L | health |
| Manganese | 0.12 health, 0.02 staining | black stains, and a health limit too |
| Iron | 0.1 mg/L (Ontario 0.3) | orange stains, metallic taste |
| Sodium | 200 mg/L aesthetic | over 20 mg/L is reported to the Medical Officer of Health |
| Hardness | no guideline | over 200 mg/L is considered poor |
| Hydrogen sulphide | 0.05 mg/L (Ontario) | rotten eggs |
Ask the lab whether nitrate is reported as nitrogen or as nitrate. 10 and 45 are the same limit written two ways, and mixing them up gives you either a panic or a false sense of comfort.
On a new well, or a well that is new to you, run a full chemistry package once, then repeat the parts that matter to you. Near farm fields, nitrate is worth a look more often. Before you buy any treatment equipment, test first, because a softener does not fix bacteria, nitrate or arsenic, and a salesman’s free kitchen-table test is not a lab report. The iron filter vs softener page and the RO vs carbon page take the results from here.
When to Test, and When to Shock the Well
Ontario says at least 3 times a year, including spring and fall, and the Simcoe Muskoka health unit adds every time you open a cottage. Test again after a flood near the well, after any work on the well or a new pump, and any time the water changes colour, taste or smell. Water is a lot like a teenager: when it suddenly acts different, something happened.
If the bacteria test is bad, the usual first step is shock chlorination: a strong dose of chlorine put into the well and drawn through the house plumbing to kill what is living there. Durham Region Health’s sheet sets the dose by the casing diameter and the depth of water in the well. The chlorinated water sits in the plumbing 12 hours. Take carbon filters out first. Do not run the chlorinated water onto the septic bed; the bed runs on bacteria too, and the SepticReplacement.ca site covers how a septic bed works. Sample again 3 to 4 days later, and drink it only after two safe results in a row.
Get the health unit’s sheet and follow it, or hire a licensed well contractor. Shocking a well with a cracked cap or surface water running down the casing only buys a few clean weeks; fix the cause.
Never climb into a dug well or a well pit. Not to sample, not to pour chlorine, not to fetch a dropped bucket. Gases and low oxygen in those spaces kill people every year. Call a licensed well contractor.
Buying a House With a Well
A bacteria result the seller hands you tells you what the water was like on the day somebody chose. Ask for a sample that you or your inspector take, and make the offer conditional on a clean bacteria test and a chemistry report. The flow, the well record and the rest of the lot questions are on the well water on a lot page.
Year one on a new-to-you well, our estimate: a well inspection and water test at the middle of the $300 to $600 range, $450; a fuller chemistry package if the inspector’s test leaves out metals, arsenic and uranium, about $200; three free bacteria tests, $0. $450 + $200 + $0 = $650, plus shipping. Cheap insurance, against the price of a house.
The results then tell you what treatment you need, if any; the water testing and treatment guide lays out the options.
Questions people ask
Is well water testing free in Ontario?
The bacteria test is. Public Health Ontario tests for total coliforms and E. coli at no charge, with bottles from public health units and pickup points. Chemistry such as arsenic, nitrate, iron and hardness goes to a licensed private lab for about $100 to $400, depending on the package.
How long do well water test results take?
Usually 2 to 4 business days through Public Health Ontario’s online portal, as long as the bottle reached the lab within 48 hours of collection.
What does “significant evidence of bacterial contamination” mean?
Total coliform over 5 with no E. coli. Something from the surface is getting into the well. Find the cause, usually shock chlorinate, and retest; your health unit will tell you what they recommend.
Can I drink the water if E. coli is found?
No. Boil it or use another source until the well is fixed and two clean tests in a row come back.
How often should I test my well?
At least 3 times a year, including spring and fall, and every time you open a cottage, plus after a flood, after work on the well, or when the water changes.
Turn the lab report into a plan
The water treatment selector takes your lab results, bacteria first (it will not recommend anything without a recent bacteria test), and gives you the treatment in the usual order with the installed and yearly cost of each step. If a dealer has already quoted you, the $99 review reads one quote against your water test report, or up to three quotes side by side.
Sources and further reading
- Public Health Ontario: well water testing: the bacteria test, the 48-hour rule for samples, and how to read the result.
- Testing and treating private water wells: Ontario on free bacteria testing, private lab chemistry and disinfecting a well and the house plumbing.
- Durham Region Health: shock chlorination: the bleach dose by casing size, the 12-hour soak, keeping it off the septic bed and the retest.
