Water problem
Bacteria in well water
Private wells are not regulated the way public supplies are, and no one tests them but the owner. A positive coliform result means a pathway exists between the surface and the water, which is a construction question as well as a treatment one.
What you might notice
- Usually none. Water can look and taste normal while testing positive
- Gastrointestinal illness in the household with no other explanation
- A well head below grade, or flooding around it
- A septic system close to the well
Nobody is testing this but you
Public water systems are sampled on a fixed schedule, and results are reported to a regulator and published annually. A private well has none of that. There is no monitoring, no report, and no one who will contact you if something changes.
That is the single most important fact about owning a well. Whatever is in the water has been in it, unobserved, for as long as you have been drinking it, and the only way that changes is if you arrange a test.
Annual testing for total coliform and E. coli is the standard recommendation. It is inexpensive relative to almost any other household maintenance, and it is the only thing standing between a change in your well and your family drinking it.
What a positive result means
Total coliform bacteria are common in soil and surface water and are not usually harmful themselves. Their presence means a pathway exists between the surface and your water, which is the real finding. Something is getting in.
E. coli is a different matter. It indicates faecal contamination and it needs immediate action: stop drinking the water, use bottled or boiled water, and treat the situation as urgent rather than as a maintenance item.
Either result should prompt a physical inspection before any equipment is discussed. A cracked or missing well cap, a casing that has failed, a wellhead below grade that floods, or a septic system too close are the common pathways, and each is a repair rather than a filtration problem.
Fix the pathway, then disinfect, then retest
The sequence matters. Repair whatever is letting contamination in. Shock chlorinate the well and the plumbing. Wait for the chlorine to clear, then retest.
If the retest is clean and the pathway was clearly identified and fixed, continuous treatment may not be necessary. If it comes back positive, or if the source cannot be found, ultraviolet disinfection certified to NSF/ANSI 55 Class A is the standard continuous answer, always with sediment pre-filtration ahead of it.
Installing a UV lamp over an unrepaired intrusion treats the symptom and hides the fault. It also means the household is relying entirely on a lamp that needs annual replacement and stops working in a power cut.
How to confirm it
An annual laboratory test for total coliform and E. coli is the standard recommendation for any private well. Total coliform indicates a pathway. E. coli indicates faecal contamination and needs immediate action, including boiling or bottled water until it is resolved.
The test that settles this is laboratory total coliform and e. coli test, annually at minimum. We include what we can measure on site in a free water test, and we will tell you plainly when a certified laboratory is the right next step rather than anything we can do at your kitchen tap.
When not to treat it
Treatment is not the first step when the cause is a failed well cap, a cracked casing, or surface water entering the well head. Fix the pathway first, shock chlorinate, then retest. Installing a UV lamp over an ongoing intrusion treats the symptom and hides the fault.
Treatment options that actually apply
These are the equipment types that address this problem. Each page states what the equipment does not do, so you can rule it out quickly if your situation does not match.
- Ultraviolet disinfection. A lamp that inactivates bacteria, viruses, and protozoa as water passes through.
- Well water systems. A treatment train assembled around a current laboratory test, in stages.
- Sediment filters. A mechanical filter that captures sand, silt, rust flakes, and other particles.
What none of these will do
- Anything chemical. Lead, nitrates, arsenic, PFAS, and hardness all pass through unchanged.
- Turbidity. Cloudy water shields organisms from the lamp, so a sediment pre-filter is required, not optional.
- Recontamination downstream of the lamp.
Getting it installed
Once a test has confirmed the problem and narrowed the equipment, the practical questions are access, space, and whether anyone's permission is needed. Those are covered on the installation pages, along with what a visit involves and how long it takes.
- Free water testing. 45 to 60 minutes.
- All installation services
- What installation costs
Other water problems
Sources
- Private Drinking Water Wells. US Environmental Protection Agency, 2024.
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