Water Purification · Wells
Well Water: Testing and Treatment, In the Right Order
A private well means the water plant is you. Ontario gives you the testing for free — here's how often to use it, what the results mean, and how treatment actually fits together.
How often should well water be tested — and what does it cost?
Ontario recommends testing your well water for bacteria at least 3 times a year — and the testing is free through Public Health Ontario, via your local public health unit: you pick up a sample bottle, fill it following the instructions, and drop it back for lab analysis. Test in spring, mid-summer and fall, and additionally after flooding, after any well or plumbing work, and whenever the taste, smell or colour changes. Three free tests a year is the cheapest insurance in homeownership — most well problems are found by the test, not by getting sick.
What do the results actually mean?
The lab reports two numbers. E. coli is the serious one: any detection means the water has been in contact with fecal contamination and is not safe to drink until the source is fixed and repeat tests come back clean. Total coliform is the warning light: these bacteria are common in the environment, and a positive result with no E. coli usually means surface water or soil bacteria are finding a path in — a well cap, seal or grading problem to correct, plus disinfection, rather than an emergency. Both results are telling you the same thing in different volumes: your well's defences have a gap. A single clean test after a bad one isn't the all-clear either — public health guidance is built on repeat samples.
What are the signs your well water needs treatment?
- Orange or brown staining on fixtures and laundry → iron (or manganese)
- Rotten-egg smell, especially from hot water → sulphur bacteria / hydrogen sulphide
- White scale crusting kettles, taps and showerheads → hardness
- Grit or cloudiness after heavy rain → sediment — and a possible surface-water path into the well worth checking alongside any bacteria result
- A bacteria result that keeps coming back → a disinfection need (UV), after the well's physical defences are checked
What does a full well-water treatment system look like?
A treatment train, in this order: a sediment filter first, then an iron filter if iron or sulphur is present, then a water softener for hardness, then UV disinfection as the bacteria safety layer, and reverse osmosis at the kitchen tap for drinking water. Not every well needs every car on the train — the test results and the symptoms decide. The full product-by-product breakdown is on the water treatment hub.
Well water — common questions
Can I just shock-chlorinate the well instead of installing UV?
Chlorination is a legitimate one-time fix after a contamination event or well work — but it doesn't protect you next month. If bacteria findings recur, continuous UV disinfection is the standing defence, because it treats every litre, every day, without chemicals in the water.
My test was clean, but the water still stains everything. Contradiction?
No — the free public health test checks bacteria, not minerals. Iron, hardness and sulphur are quality problems the bacteria test doesn't measure. Staining with a clean bacteria test means you need the treatment conversation (iron filter, softener), not the safety one.
Does UV change the taste of the water?
No — UV adds nothing and removes nothing; it only inactivates microorganisms. Taste improvements come from the other cars on the train — iron filtration, carbon, or reverse osmosis at the tap.
Not sure what your well needs?
Answer a few questions about your water — source, symptoms, what you have now — and see the treatment train that fits, in the right order.
Take the Water Check