Nitrate Water Test

Who should test for nitrate

CDC says all well owners should test for nitrates at least once every year, as part of a yearly check that also covers total coliform bacteria, total dissolved solids and pH. A public water system tests for nitrate under federal rules. A private well is tested only when its owner orders a test. Our water testing home page explains why that makes testing a well worth doing.

Why nitrate matters most for babies. EPA's drinking water table names infants below the age of six months as the group at risk. It says infants who drink water containing nitrate above the federal limit could become seriously ill and, if untreated, may die, and it lists shortness of breath and blue-baby syndrome among the effects. CDC puts it the same way: high levels of nitrates in your water can make you, and especially babies, sick.

Where nitrate in a well comes from. Nitrate usually reaches a well from the land around it. EPA lists the sources as runoff from fertilizer use, leaking from septic tanks and sewage, and erosion of natural deposits. CDC's list for well water is longer: animal waste, septic systems, wastewater, flooded sewers, polluted storm water runoff, fertilizers, runoff from farms, and decaying plants. If your well sits near fields, livestock, or your own septic system, that is a reason to keep up a yearly nitrate test.

When to test outside the yearly schedule. CDC lists times when you should have your well water tested again. Several of them matter for nitrate:

• You or someone you live with becomes pregnant.
• A child starts living with you.
• There are problems near your well, such as flooding, land disturbances, or nearby waste disposal sites.
• You replace or repair any part of your well system.
• You notice a change in your water's taste, color or smell.

If a baby will drink your well water. A nitrate test before a pregnancy or a child's arrival tells you where your well stands at the time that matters most. If you get a result above the federal limit, talk to your local health department and a health professional about what the baby should drink.

Nitrate alongside other well tests. Nitrate is rarely the only test a well needs. To see it next to bacteria and the other tests that fit your home, you can build a test plan in a few questions, or read our well water testing guide for the full yearly well check. If a bacteria test comes back positive, our guide to bacteria in well water covers what the result means and how to fix it.

Certified lab or home kit

There are two ways to check your water for nitrate: send a sample to a state-certified laboratory, or use a kit you read at home. Only a certified lab gives you a measured concentration you can compare with the federal limit.

A certified lab gives you a number. A state-certified drinking water lab measures how much nitrate is in your sample, using approved methods such as the ones in the Lab methods list at the end of this section. It reports the result as a concentration you can compare with the EPA limit and with your own earlier results. CDC tells well owners that their state or county health department should have a list of state-certified (licensed) laboratories. Our directory of certified water testing labs lists state-certified labs in the states we cover, and our guide to well water testing cost shows verified lab prices.

Nitrate and nitrite. EPA sets separate limits for nitrate and for nitrite, and both are measured as nitrogen. When you order, check whether the test reports nitrate, nitrite or both. If you searched for a nitrate nitrite water test, that is the question to ask the lab.

A home kit gives you a rough read. You may see nitrate strips or kits you read at home by matching a color to a chart. A color you match yourself is not a measured concentration from a certified lab, and you can't compare it with a regulatory benchmark in the same way. A strip that shows little or nothing does not prove your water is below the federal limit. Our guide on how to test water quality compares a certified lab, a mail-in kit and test strips, and explains where to get a water sample checked.

When to choose a certified lab:

• You want a number to compare with the EPA maximum contaminant level.
• Someone in the home is pregnant, or a baby will drink the water.
• You are buying or selling a home with a well and need a result you can show someone else.
• You are deciding whether to spend money on treatment, or checking whether treatment works.
• A home kit showed anything at all, and you want to confirm it.

Use a home kit as a screening step if you like, and confirm anything that matters with a certified lab.

Lab methods

• EPA 300.0 (ion chromatography)
• EPA 300.1 (ion chromatography)
• EPA 353.2 (automated cadmium reduction)

Source: ecfr.gov (source for lab methods) (opens in a new tab)

How to collect a nitrate sample

A nitrate sample is one of the simpler samples to take. Nitrate usually comes from the well water itself, not from your plumbing, so you are not trying to catch water that sat in the pipes overnight. Always follow the instructions in your lab's kit, since they are written for that lab's bottle and method.

The quick guide near the top of this page lists the sample bottle and handling that the federal method calls for. Many labs send bottles that are ready to fill, so the steps below keep to what applies to most kits.

1. Check the timing. Read your lab's instructions for how soon the sample must reach it, and which days it can receive samples. Collect close to a shipping or drop-off time.
2. Pick the right tap. Use a cold-water tap you drink or cook from, usually the kitchen sink. If you have any treatment device, ask the lab whether to sample before it, after it, or both. Sampling before treatment tells you about the well; sampling after it tells you what you are drinking.
3. Remove any attachments. Take off a hose or attachment on the faucet, unless your kit says otherwise.
4. Run the cold water. Let it run until it is steady and cool, so the sample represents water from the well and not water that sat in a warm pipe. Your lab's instructions give the exact time.
5. Fill the bottle without rinsing it. Don't rinse out anything the lab put in the bottle, and don't let it overflow. Fill to the line, then cap it tightly. Avoid touching the inside of the cap or bottle.
6. Label and record. Write the date, time, tap and whether the sample was taken before or after any treatment.
7. Pack and send. Pack the sample the way your lab asks, using any cooler or cold pack it provides, and send it within the time your lab gives you.

If you are testing for bacteria or anything else at the same time, read every bottle's instructions first and plan your collection day around the bottle with the shortest window.

Common mistakes to avoid

• Sampling only after a filter or softener when you wanted to know about the well itself.
• Rinsing out a bottle that came with something already inside.
• Sampling from an outdoor spigot or a hose when you wanted to know about your drinking water.
• Holding the sample past the return date your lab gives you.

What your nitrate level means

Your lab report gives a number. Here is how to read it against the federal benchmarks.

The EPA maximum contaminant level (MCL) for nitrate is 10 mg/L^[2], measured as nitrogen. It is the legal limit for public water systems. Private wells don't have to meet it, but it is the federal benchmark you can compare a well result with. EPA's health goal (the MCLG) for nitrate is the same value, 10 mg/L^[2].

The MCL for nitrite is 1 mg/L^[2], also measured as nitrogen. EPA gives nitrite the same warning about infants below six months of age.

Check the units on your report. Both limits are written as nitrogen. Look for "as N" or "as nitrogen" next to your result. If your report gives nitrate in another form, ask the lab to give it to you as nitrogen before you compare it with the limit.

Don't boil water to deal with nitrate. EPA is direct about this: boiling water will not reduce nitrate levels. It makes the level worse, because some of the water evaporates but the nitrate does not, so the nitrate becomes more concentrated.

A water test can't diagnose anything. If you have health concerns, or a baby in your home has been drinking the water, talk to a health professional and bring your lab report. Our guide to nitrates in water covers the health effects, where nitrate comes from and what to do after a confirmed result.

Putting your result in context

• No nitrate detected. No treatment needed based on this result. Keep the report as a baseline and retest each year, as CDC advises.
• Nitrate detected, below the MCL. No treatment needed based on the federal limit. Keep testing every year, and again if someone in your home becomes pregnant or a child starts living with you.
• At or above the MCL. Retest with a certified lab to confirm before you make any decision. If an infant drinks this water, talk to your local health department and a health professional about what the baby should drink in the meantime, and don't boil the water to fix it.

Don't decide on treatment from a single home-kit reading. Any treatment choice should start from a confirmed certified-lab result, and a retest after any change shows whether it worked.