Most well water advice is written for a general household. Pregnancy changes the priorities, and it changes one piece of standard safety advice into something actively dangerous.
If you are pregnant, planning a pregnancy, or about to bring a baby home to a house on a private well, this is the short list.
Test these four
1. Nitrate — the most time-critical.
2. Lead — no safe level is recognised; particular concern in pregnancy and early childhood.
3. Arsenic — long-term exposure concerns including developmental effects.
4. Bacteria — total coliform and E. coli.
Everything else can wait. These four cannot.
Nitrate, and the boiling trap
Nitrate deserves the most space because the risk is specific, the window is narrow, and the common-sense response makes it worse.
The limit is 10 mg/L as nitrate-nitrogen (NO₃-N). Check the basis on your report — some labs report as NO₃, where the equivalent figure is about 45 mg/L. Reading the wrong basis is the single most common misinterpretation on a well report, and our guide to reading results covers it.
In infants under roughly six months, nitrate converts to nitrite, which binds to haemoglobin and blocks oxygen transport. The result is methaemoglobinaemia — "blue baby syndrome". Early signs are a bluish tint around the mouth and lethargy. It is a medical emergency and it is entirely preventable with a test.
Pregnant women should follow the infant standard rather than the adult one.
Now the trap:
Boiling water does not reduce nitrate. It increases it. Water leaves as steam; nitrate stays behind; the concentration goes up.
Everyone knows boiling makes water safe, because for bacteria it does. For nitrate, arsenic, lead and uranium it does the opposite. If you boil water before mixing formula on a high-nitrate well, you have made the exposure worse than if you had not.
For nitrate: bottled water, or reverse osmosis. Not the stove. Our boiling guide sets out exactly what boiling fixes and what it worsens.
Lead
The action level is 0.015 mg/L, but understand what that number is: it is a regulatory trigger, not a safety threshold. The EPA sets the health goal for lead at zero, because no level is considered safe — and the concerns are sharpest for infants, young children and pregnancy.
On a private well, lead is almost never in the aquifer. It dissolves out of your own plumbing: lead solder on copper joints (legal in the US until 1986), brass fittings, older faucets. Acidic water is what drives it, which is why low pH and lead travel together.
Two practical points that matter enormously during pregnancy:
- Sample first-draw — the first water from a tap that has sat overnight, without flushing first. That is the water in your morning glass. A flushed sample can read clean on a house that is genuinely leaching.
- Never use hot water for drinking, cooking or formula. Hot water dissolves lead faster. Draw cold and heat it separately.
Our lead guide covers the full picture.
Arsenic
The limit is 0.010 mg/L (10 µg/L). Watch the units — 0.012 mg/L and 12 µg/L are the same result, and both exceed the limit, but one looks reassuringly small.
Arsenic is naturally occurring in bedrock across large parts of the country, tasteless, odourless and colourless. There is no way to detect it without a test, and long-term exposure concerns include developmental effects.
It is also, like nitrate, concentrated by boiling.
Bacteria
Total coliform and E. coli are presence/absence tests, and any detection is a fail. Pregnancy brings some immune changes, and a gastrointestinal infection during pregnancy is worth more effort to avoid than at other times.
If bacteria are present: use bottled or properly boiled water — boiling is correct here — then shock chlorinate, flush, and retest for both. Our E. coli guide covers the urgency.
Timing
Test early. Not in the last month, and preferably while planning.
The reason is practical. If something comes back high:
- A lab panel takes one to two weeks to return
- Specifying and installing treatment takes weeks more
- A retest after treatment is essential — an installed system that does not perform is a common and invisible failure
That is comfortably two months of lead time, and nobody wants to be arranging reverse osmosis in week 38.
If a result comes back high
Switch to bottled water for drinking, cooking and formula immediately. It is cheap, it is instant, and it removes the time pressure from every other decision.
Then treat the cause: reverse osmosis at the kitchen tap handles nitrate, arsenic, lead and uranium for drinking water. A neutraliser addresses the acidity driving lead. Treatment order covers how the stages fit together.
Then retest the treated water and keep both results with their dates. That pair — before and after — is the only evidence you will ever have that the system is actually doing its job, and it is the thing you will want on record when the next baby, or the next owner, arrives.
Frequently Asked Questions
What should I test my well water for during pregnancy? Four things at minimum: nitrate, lead, arsenic and bacteria. Nitrate is the most time-critical because of its specific risk to infants under six months. Test during pregnancy rather than after the birth, so there is time to fix anything that comes back high.
Why is nitrate dangerous for babies? In infants under about six months, nitrate converts to nitrite, which binds haemoglobin and blocks oxygen transport — a condition called methaemoglobinaemia or blue baby syndrome. The EPA limit is 10 mg/L as nitrate-nitrogen. Formula mixed with high-nitrate water is the classic exposure.
Can I boil well water to make it safe for formula? Not for nitrate, and this is the most dangerous misconception in well water. Boiling kills bacteria but evaporates water while nitrate stays behind, so it raises the concentration. For high nitrate use bottled water or water treated by reverse osmosis.
Is bottled water safer than well water for making formula? If your well tests above the limit for nitrate, lead or arsenic, yes — use bottled or properly treated water until the problem is fixed. If your well tests clean, there is no inherent advantage to bottled water. The answer depends entirely on having tested.
When should I test if we are planning a pregnancy? Before, ideally. Treatment for nitrate or arsenic takes weeks to specify and install, and a retest after treatment is essential to confirm it worked. Testing early in pregnancy, or while planning, leaves room for all of that without pressure.