A notice from your water utility: what it means and what to do

First, find out which kind it is

Every notice has to tell you what to do with your water, so start there. Under EPA's rule, a notice must also say what happened and when, what it could do to health, and who is most at risk. It must say whether to use another source of water, what the utility is doing about it, when it expects to fix it, and who to call.

How fast it reached you says how urgent EPA considers it. EPA sorts notices into three tiers:

• Tier 1, within 24 hours, for a situation with the potential to affect health right away. That includes germs such as E. coli, nitrate or nitrite over the legal limit, and a lead level over the action level.
• Tier 2, within 30 days, for other water over a legal limit: total trihalomethanes (TTHM), haloacetic acids (HAA5), arsenic and the like.
• Tier 3, within a year, for violations with no direct impact on health, such as a sample taken late or not at all.

A boil water advisory

The water may have germs in it, and boiling kills them. CDC's instructions:

• Bring the water to a full rolling boil for 1 minute, or 3 minutes at elevations above 6,500 feet, and let it cool.
• Boil it even if you filter it. CDC says that includes water from a home filter or a filter pitcher.
• Don't use the refrigerator's water or ice dispenser. CDC says that holds for any drinking water advisory.
• For a baby, use ready-to-use formula if you can, CDC says.

Boiling only deals with germs. CDC says it does not remove chemicals.

A do not drink, or do not use, advisory

A do not drink advisory means the water is, or might be, contaminated with harmful chemicals or toxins. Boiling won't help: CDC says boiling water with harmful chemicals or toxins won't make it safe. Use commercially bottled water for drinking and cooking, and CDC adds making ice, brushing teeth, mixing baby formula, washing produce and giving water to pets.

A do not use advisory is rarer and more serious: CDC says not to drink or use tap water for any purpose until it's lifted, and to use bottled water for everything.

Nitrate: the notice that's urgent for babies

A nitrate notice is a 24-hour notice because infants under six months are the ones at risk. EPA says they could become seriously ill, with shortness of breath and blue-baby syndrome among the symptoms.

• Don't use the water for an infant's formula or food. EPA advises against water with more than 10 mg/L of nitrate, and suggests bottled water instead. CDC adds ready-to-feed formula, which needs no water.
• Don't boil it to make it safe. CDC says boiling can't make water with harmful chemicals safe.

On a private well, no utility sends a notice; arsenic and nitrate in well water covers testing for both.

A letter about TTHM, HAA5, arsenic or another limit

These arrive as 30-day notices. EPA's health concern for these contaminants is drinking the water over many years, not a single day, which is why the rule doesn't treat them as Tier 1. A letter like this usually says you don't need another water supply; follow what yours says.

What helps in the meantime is a filter certified for that contaminant, at the tap you drink from. For TTHM, the TTHM filter picks rank the filters with that claim on a certifier's listing. Your utility's record on TapBuff lists every health-based violation since 2016, so you can see whether this is the first or one of many.

Lead over the action level

A lead action level notice is now a 24-hour notice. Your own plumbing decides most of the lead at your tap, so the steps are the same whether or not your home was sampled. Use only cold water for drinking, cooking and formula, run the tap after the water has sat, and use a filter certified for lead. Lead in your water: what to do now has each step with its source.

Look up your utility's record

What EPA's and your state's records show for your utility, with every violation since 2016: