Bacteria & Coliform in Iowa Well Water: Testing & Fixes

The short answer

Test every year: The Iowa DNR recommends testing every private well annually for bacteria and nitrate, and Iowa's Private Well Grants program covers free county lab testing through your county environmental health office.
What coliform indicates: A total coliform result indicates bacteria common in soil and surface water reached the well, meaning a pathway exists from the surface; it is not itself evidence of sewage contamination.
County health first: If E. coli is present, your county public health office should be the next call rather than a water treatment company.
Fix the pathway: Shock chlorination is the standard remediation, but disinfecting a well without fixing the entry point — a cracked casing, failed seal, shallow well or flooding — just resets the clock.
UV cost and upkeep: A UV system is $700 installed, needs clear water ahead of it, and its lamp is a consumable replaced every six to twelve months at $300 per swap.
What does not apply: A softener treats hardness only, a neglected carbon filter can harbor growth, and a kitchen-sink reverse osmosis system treats one tap rather than the shower or the ice maker.

Bacteria is the one private-well problem you cannot see, smell or taste — which is why the Iowa DNR recommends testing every private well every year for bacteria and nitrate, and why Iowa's Private Well Grants program covers free county lab testing through your county environmental health office. If you own a well in Eastern Iowa and have not tested in the last twelve months, that free test is the whole job right now.

What a coliform result actually means

Labs report two things, and they are not the same:

Result	What it indicates	What it does not mean
Total coliform present	Bacteria common in soil and surface water reached your well. It is an indicator that a pathway exists between the surface and your water — a cracked casing, a bad seal, a shallow well, flooding	It is not itself evidence of sewage contamination
E. coli present	A specific fecal indicator. This is the serious result and your county public health office should be your next call, not a water treatment company	—
Absent / none detected	No indicator bacteria in that sample, on that day	It does not certify the well permanently — which is why the guidance is annual

We are deliberately not going to tell you what bacteria does to people. That is your county health department's job and they do it better than a water company should. What we can tell you is the plumbing side: where bacteria gets in, and what equipment keeps it out.

How bacteria gets into an Iowa well

Almost always a physical pathway rather than the aquifer itself:

Well depth and geology. Shallow and alluvial wells are far more exposed than deep bedrock wells. The Iowa DNR rates aquifers on exactly this — it rated the alluvial aquifer under Marengo "highly susceptible to contamination," and the Silurian under Lisbon and Mount Vernon the same way, while deep Cambrian-Ordovician systems are rated low susceptibility.
Casing and cap failure. A cracked casing, a missing or unsealed cap, or a rusted-through steel casing gives surface water a direct route.
Flooding. Any well that goes underwater should be treated as contaminated until tested. See our flooded well guide.
Abandoned wells nearby. An unplugged old well is an open pipe into the aquifer.
Pressure tank and plumbing biofilm. Sometimes the well is fine and the sample is picking up something inside the house.

What to do, in order

Test through your county. Free, through your county environmental health office under Iowa's Private Well Grants program. Get the actual lab result on paper.
If E. coli is present, call county public health first. Before you call any water treatment company, including us.
Find the pathway. Inspect the cap, seal, casing and grouting. Disinfecting a well without fixing the entry point just resets the clock — you will be back in six months.
Disinfect the well. Shock chlorination is the standard remediation, and Iowa DNR and county health offices publish the procedure. A licensed well contractor is the right party for a well with a physical defect.
Retest after disinfection. Then retest again a few weeks later. One clean sample after chlorination proves the chlorine worked, not that the pathway is closed.
Consider continuous disinfection if the well tests positive repeatedly and the defect cannot be eliminated.

Where equipment fits — and where it does not

UV disinfection — $700 installed. A UV system treats water continuously as it enters the house. It is the standard answer for a well that keeps testing positive after the physical problems have been addressed. Two honest caveats: UV needs clear water to work, so iron, sediment or tannins have to be filtered out ahead of it or they shield bacteria from the lamp; and the lamp is a consumable, replaced every six to twelve months at $300 per swap. A UV system nobody maintains is a decorative tube.

What does not solve bacteria: a water softener (it treats hardness, full stop), a carbon filter (it can actually harbor growth if neglected), or a reverse osmosis system at the kitchen sink — which treats one tap, not the shower, the ice maker or the tap the kids drink from in the bathroom.

UV is well-water equipment. We do not install it on city water, where the utility already maintains a disinfectant residual all the way to your house.

What it costs

Item	Price
County lab test for bacteria and nitrate	Free — Iowa Private Well Grants, via your county environmental health office
Our in-home water test (hardness, iron, TDS)	Free, no obligation
UV disinfection system, installed	$700
UV bulb replacement (every 6–12 months)	$300
Pre-sediment filter (often required ahead of UV)	$500
Well dual-tank system + tank RO	$3,800 (no RO: $3,450)

Iron and sulfur systems are quoted after testing. More: well water guide, free well testing in Iowa, well water treatment.

Get tested first

We would rather you spend nothing with us and get the free county test than buy a UV system you may not need. When you have the lab result, send it over and we will tell you what — if anything — the plumbing side calls for. Call or text 319-319-6566, email ryan@kindwaterco.com, or get an instant quote.

Frequently asked questions

How often should I test my well for bacteria in Iowa?

Every year. The Iowa DNR recommends annual testing of private wells for bacteria and nitrate, and Iowa's Private Well Grants program covers free county lab testing through your county environmental health office. Bacteria cannot be seen, smelled or tasted, so testing is the only detection method available to you.

What does it mean if my well tests positive for total coliform?

It indicates that bacteria common in soil and surface water reached your well — meaning a pathway exists between the surface and your water, such as a cracked casing, a failed seal, a shallow well, or flooding. It is an indicator result. If E. coli is detected, contact your county public health office first.

Will a water softener or filter remove bacteria?

No. A softener treats hardness only. A carbon filter can actually harbor growth if neglected. A reverse osmosis system treats one tap, not the shower or ice maker. Continuous UV disinfection is the standard equipment answer, at $700 installed — after the physical entry point has been found and fixed.

How much does a UV system cost for well water?

$700 installed, all-in with a licensed plumbing professional and taxes. The lamp is a consumable replaced every six to twelve months at $300. UV also needs clear water, so a pre-sediment filter at $500 is often required ahead of it — iron and sediment shield bacteria from the lamp.

Do I need to shock chlorinate my well?

Shock chlorination is the standard remediation after a positive bacteria result, and Iowa DNR and county health offices publish the procedure. Find and fix the entry point first — disinfecting without closing the pathway just resets the clock. Retest after treatment, then retest again a few weeks later.

Bacteria and Coliform in Iowa Well Water