Well water with a baby on the way: what to test

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Test the well before the baby comes home

The CDC lists a pregnancy in the house as one of the times to test a private well. The Minnesota Department of Health (MDH) says to test before or during pregnancy, and again before you bring a new baby home if you haven't yet.

Babies drink more water for their size than adults do, and their bodies are slower to get rid of harmful substances, MDH says. The AAP (American Academy of Pediatrics) adds that water adults drink without problems can still make a child sick.

Test early. If a result comes back high, you'll want time to retest, fix the well or set up bottled water before the due date.

Sample the tap you'll use for formula. MDH says that might be the kitchen faucet, a refrigerator dispenser, a filter with its own tap, or a filter pitcher. A filter changes the water, so test what comes out of it.

Run these 4 tests before the due date

These are the tests MDH recommends for a home with a baby on the way, and the line each result should stay at or under for a baby's water:

• Nitrate, every year: 10 mg/L or less.
• Coliform bacteria, every year: none found.
• Manganese, at least once: 100 µg/L or less.
• Lead, at least once, from a first-draw sample: the EPA's health goal is 0.

Check the units on your report. Results in mg/L (milligrams per liter) are the same as parts per million. Results in µg/L (micrograms per liter) are parts per billion. 1 mg/L is 1,000 µg/L, so a manganese result of 0.1 mg/L is 100 µg/L, right at the line for a baby.

MDH also recommends testing once for arsenic, and says to treat the water or use another source if it's over 10 µg/L. For fluoride, MDH suggests asking your baby's doctor or dentist whether to test.

Nitrate matters most for a bottle-fed baby

Nitrate comes from fertilizer, manure and septic systems. In a young baby, it keeps the blood from carrying enough oxygen, a condition called methemoglobinemia or "blue baby syndrome." MDH says bottle-fed babies under 6 months are at the highest risk. The EPA says babies under 6 months who drink water high in nitrate can become seriously ill.

The limit is 10 mg/L, measured as nitrogen. Reports often write that as "nitrate as N" or "NO3-N." If your report lists the whole nitrate ion instead, the same limit is about 45 mg/L. Call the lab if the report doesn't say which.

A result under 10 still tells you something. MDH says natural levels are usually under 3 mg/L, so a result between 3 and 10 points to a human-made source such as fertilizer, manure or a septic system, and the level could climb. Test again every year. More on nitrate.

Manganese has a lower line for babies

Manganese occurs naturally in rock and soil. It can leave brownish-black stains on sinks and toilets, and MDH says the only way to know the level is a test.

For a baby who drinks tap water or formula made with it, MDH's guidance is 100 µg/L or less. For older children and adults, it's 300 µg/L. The EPA advises keeping babies under 6 months off water over 300 µg/L (0.3 mg/L) even for 10 days, because young babies may absorb more manganese and get rid of less.

Formula already has some. The EPA's health advisory notes that infant formulas contain 50 to 300 µg/L of manganese, compared with about 3.5 to 15 µg/L in breast milk. Water high in manganese adds to that. MDH says babies who drink too much may develop learning and behavior problems.

Bathing in it is fine, MDH says. The concern is water a baby drinks. More on manganese.

Any coliform bacteria means the well needs work

Labs report coliform bacteria as present or absent, or as a count. Coliforms live in soil and surface water, and the CDC says they get into wells the same way as germs that make people sick. MDH says any level may be harmful, and babies and children are more likely to get sick from the germs that can come in with them.

If the lab also finds E. coli, the CDC says waste from people or animals has probably reached the well.

If coliforms show up, MDH says to stop using the water for drinking and food unless you boil it at a full rolling boil for 1 minute, or use bottled water. Disinfect the well, then retest. You can use the water without boiling once a test comes back clean. Our shock chlorination guide walks through the disinfection, and bacteria has more on what each result means.

Lead comes from plumbing, so test the first water of the morning

The AAP lists the usual sources: brass parts in a submersible pump, solder, and old lead pipes. The EPA says the longer water sits in the pipes, the more lead it may contain.

That's why the test uses a first-draw sample. Penn State Extension says to collect it first thing in the morning, from cold water that sat in the plumbing overnight. Take it from the tap you'll use for formula, and ask the lab for "total lead," which counts small particles too.

The EPA's health goal for lead is 0, and MDH says any level is harmful. The EPA estimates that babies who drink mostly formula mixed with tap water can get 40% to 60% of their lead from that water. So a first-draw result that shows any lead is worth lowering before the baby arrives.

The EPA says to use only cold water for drinking, cooking and making formula, and a filter certified to remove lead if you use one. More on lead.

Boiling kills germs, and it makes nitrate stronger

Boiling water for 1 minute kills bacteria, viruses and parasites. It doesn't remove chemicals, and for nitrate it makes things worse. MDH and Penn State both say boiling makes nitrate more concentrated, because some water boils off and the nitrate stays behind. The EPA says boiling doesn't remove lead.

For water with harmful chemicals in it, the CDC says to mix formula with bottled water or use ready-to-feed formula.

You may be boiling water anyway. For babies younger than 2 months, babies born early and babies with weakened immune systems, the CDC says to boil the water and let it sit about 5 minutes before mixing powdered formula. That very hot water kills germs that can be in the powder. It won't lower nitrate or lead, so start with well water that tested at or under the nitrate line and low in lead, or with bottled water.

Use bottled water or ready-to-feed formula when a result is over the line

The AAP says water over 10 mg/L nitrate shouldn't be used in formula or baby food. MDH says to use bottled water until the problem is fixed, especially for babies under 6 months on formula.

Ready-to-feed formula comes already mixed, so no water goes in. The AAP says never to add water to it.

Even after you install treatment for nitrate, MDH recommends that babies under 6 months keep drinking bottled water, in case the system stops working. Penn State calls bottled water an effective, low-cost choice for babies and pregnant women.

If you're waiting on results and aren't sure about the water, the CDC suggests asking your local health department. Bottled water for formula until then is a simple choice.

Nitrate and lead are the 2 to watch during pregnancy

Lead builds up in bones over the years. The EPA says that during pregnancy, lead is released from the mother's bones and can cross the placenta. It lists slower growth before birth and premature birth among the effects. Lead can also pass into breast milk.

For nitrate, Penn State Extension says low birth weights have been linked to high nitrate in water. MDH says newer studies tie long-term nitrate below the 10 mg/L limit to pregnancy problems, and that more research is needed to confirm it.

The AAP lists miscarriage, stillbirth and low birth weight among the possible effects of arsenic. MDH already recommends an arsenic test once, and this is one more reason to do it.

If nitrate or lead tests high, the same bottled water you buy for formula covers your own drinking water too.

Look for free testing, then pick a lab

Some states and counties test well water for free or at low cost. MDH suggests asking your county environmental or public health office. Look up your county with our county lookup to see what's common in wells near you and what your state offers.

If you're buying a kit, our lab test picks mark the ones that cover all 4 of these tests. Already have results? Our results explainer tells you which numbers are over the line.

Questions people ask