Is Well Water Safe to Drink? The Honest Answer

For the most part, well water is safe to drink. When you buy a house on a well, the sale usually includes a use and occupancy test for nitrates, bacteria and turbidity, and if those pass, you can drink all the water you want. The catch is that nobody tests it again after that unless you do, and the thing most likely to make you sick, bacteria, has no taste, color or smell.

Caller "It says total coliform was present in this sample. I don't know what that means."

Aidan "You do not want that in your water. If it colonizes or gets too strong, you'll have the worst case of stomach flu you ever had in your life."

A caller read me that line from a well test in October. This page is how to tell whether your well water is safe.

Is Well Water Actually Safe to Drink?

For the most part, yes. More than 23 million households in the United States drink from a private well, and when a house on a well is sold, a use and occupancy test checks nitrates, bacteria and turbidity (cloudiness) to make sure the water is safe to drink. If all three pass, the water is drinkable on the day of the test.

What that test does not do is keep your water safe from then on. A private well is not covered by the Safe Drinking Water Act, and most states do not regulate it either (EPA: Private Drinking Water Wells). After you move in, testing it is up to you. A flood, work on the well, or a leaking septic system can change it after it tested clean.

Many wells also have what I call secondary issues: low pH, hardness, iron, sulfur, manganese. Those cause staining and corrosion, and they matter less than bacteria and nitrates. The full list with symptoms is in well water problems and their signs.

Can Water That Tastes Fine Still Be Unsafe?

Yes. You can't taste bacteria. You could have a huge colony of fecal or coliform bacteria in your water, get flu-like symptoms, and never know it was coming from the well. The water pours clear and smells like nothing.

The same goes for nitrate, arsenic and lead. None of them has a taste, a color or a smell at the levels that matter, so the only way to know they are there is a lab test.

Your senses are good at catching the nuisance problems: the stains, the rotten egg smell, the metallic taste. They are close to useless for the health problems. Never decide your water is safe because it looks and tastes fine.

The Most Dangerous Contaminant in a Well

It could be a number of things depending on where you live, but for most people the one that affects you the most is fecal or coliform bacteria. If a colony grows too big in the well, it causes stomach flu symptoms (vomiting, diarrhea, cramps), and it can be extremely dangerous.

The lab checks two kinds. Coliform is common in well water: it turns up in about 2 in 5 of the well tests my customers send in (203 of 504). E. coli is less common, about 1 in 22 (23 of 504), and more dangerous, because it usually comes from a leaking septic system or farm animal waste. Both are reported as present or absent, and if either one is present, it has to be treated.

The fix: shock the well with chlorine, let it sit 24 hours, run the chlorine out and retest, then put a UV light where the water comes into the house after the pressure tank, so it kills the bacteria before the water goes anywhere else in the house. The whole process is in how to remove coliform bacteria from well water.

Which Test Results Mean Safe Water?

Your well water passes the health check when both bacteria tests come back absent and nitrate, arsenic and lead are under the EPA limits below. Those five are the health lines that fail most often in the well tests my customers send in. Lines like pH, iron and hardness mostly decide what happens to your plumbing.

The counts come from the well tests my customers have sent in to the lab, 510 of them. Some reports gave no number for nitrate, arsenic or lead, so those three are floors. The EPA limits are from its drinking water standards. For every other line on a report, see how to read well water test results.

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Send the first page. Aidan will tell you which lines are a problem, whether to stop drinking the water, and what fixes it.

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Does Boiling Make Well Water Safe?

Boiling kills bacteria, but it does not remove nitrate, arsenic or lead, and it can leave nitrate and arsenic more concentrated than before. As the water boils off, those stay behind in less water.

So boiling is the right stopgap for a bacteria hit and the wrong one for nitrate or arsenic. If your test found bacteria and nitrate or arsenic together, use bottled water until both are fixed.

Boiling is also only a stopgap. It makes one pot safe; it does nothing about whatever is getting into the well. Test the water, then treat the actual problem.

What Every Well Owner Should Test For

Have a certified lab test your well for bacteria and nitrates at least every 2 years. The EPA says every year, and that is the safer schedule. The EPA's yearly list is total coliform, nitrates, total dissolved solids and pH (EPA: Protect Your Home's Water). Test right away, whatever the calendar says, after a flood, after any work on the well, or when the water's taste, color or smell changes.

The health group is what you test to protect the people. The secondary group is what you fix to protect the house. How to take the sample and where to send it is in how to test well water.

No lab report yet? Certified lab test, $199

One lab test checks everything listed

One certified lab test, mailed to you, run by an accredited lab, checks 53 things, including coliform, E. coli, nitrate, arsenic and lead. Results come back in about 5 business days after the lab gets the sample.

Get the certified well water test

The First Signs Something Is Wrong

Stains and smells usually point to nuisance problems; a stomach illness points to bacteria. This is how I read the signs people describe to me.

Stains and smells are not an emergency. An unexplained stomach illness in the house is. Use bottled water until a test comes back.

Just Bought a House on a Well?

The test at the sale only covers nitrates, bacteria and cloudiness, so test for more. If you ever buy another house on a well, always ask for an inspection and a water test before you close. In Maryland, for one, a well that fails for bacteria, nitrates or turbidity has to be fixed by the seller before settlement.

1. Test for the secondary things. pH, iron, hardness, manganese, sulfur and arsenic, on top of what the state or the real estate agent had done.
2. Run a second bacteria test. Even though the sale had one, to make sure nothing was missed.
3. Fix what the results show, in the right order. The new well owner's guide goes through it.

Who Needs to Be Most Careful

Babies under 6 months are most at risk: nitrate over 10 mg/L can make them seriously ill. Nitrate cuts the blood's ability to carry oxygen ("blue baby syndrome"), and bottle-fed babies are at the highest risk, so test for nitrate before mixing formula with well water (EPA: well water contaminants). Use bottled water for the formula if nitrate is high; boiling makes it worse.

Nitrates also affect unborn babies, so if someone in the house is pregnant, test for nitrate.

What to Do If Your Test Finds Problems

Each problem in this guide has equipment that treats it. What matters is matching the equipment to your actual numbers.

• Bacteria: shock the well, then a UV light after the pressure tank. See removing coliform bacteria.
• Nitrate: reverse osmosis or an ion exchange nitrate filter, with any hardness taken out ahead of it. See nitrates in well water.
• Arsenic: an arsenic filter; the media usually lasts 2 to 3 years, depending on how much water you use. See arsenic in well water.
• Low pH, iron, hardness, sulfur: an acid neutralizer, an iron filter, a softener, a sulfur filter. See well water problems.

The order the equipment goes in matters as much as the equipment; see the correct order for well water treatment. For safe, clean drinking water, we usually recommend a carbon filter and a UV light after the initial system. If you send me your results, I'll go over them with you and tell you what your house needs.

Frequently asked questions