After a Water Main Break: Is Your Water Safe and What Should You Do?

After a water main break near you, your water is usually still safe to use unless your utility issues a boil water advisory or other notice. The main risk comes from pressure loss: when pressure drops, contaminated water can be drawn into pipes, which is why utilities often issue a precautionary boil notice for the affected area. The most common thing you’ll actually see is brown or discolored water from stirred-up sediment. Large utilities like New York City’s say not to drink obviously discolored water and to run the cold tap until it’s clear before drinking or cooking.

Here’s what’s happening in the pipes, how to tell whether you’re affected, and what to do during and after.

Why main breaks matter

Water mains are kept under pressure, so water pushes outward through any leaks. That outward pressure is a safety barrier.

EPA explains that when pressure drops, the flow can reverse. Water from outside the pipe can be pulled in through cracks, breaks or joints, and backflow from connected buildings can occur. EPA’s operator guidance (from EPA Region 8) defines pressure loss as a system pressure below 20 psi and says these events carry a high potential for fecal contamination or other disease-causing organisms to enter the system. EPA research also notes that a main break can cause low pressure in other parts of the system, not just at the break.

That’s why the size of the break isn’t the only factor. What matters is whether pressure in your area dropped low enough, for long enough, to let something in.

Main breaks are common. The American Society of Civil Engineers’ 2025 Infrastructure Report Card estimates about 240,000 water main breaks a year in the US.

Step 1: Find out if you’re in the affected area

A main break down the street doesn’t automatically affect your water. Utilities can usually isolate the damaged section by closing valves.

Check your utility’s website and social media. Many large utilities post an interactive map of the affected area. DC Water, for example, directs customers to look up their address on its map or call its 24-hour command center.
Sign up for alerts if your utility offers text or email notifications.
Watch for door hangers or notices in your building.
Report a break if you see water flowing in the street. Use your utility’s emergency line or your city’s 311 service.

If you’re not in the notice area and your water looks and smells normal, you can keep using it as usual.

Step 2: If there’s a boil water advisory, follow it

EPA Region 8 guidance tells water systems to issue a boil water notice when pressure loss is likely to last longer than one hour. Your state’s rules may differ, but the logic is the same everywhere: the notice is precautionary until testing shows the water is safe.

During a boil advisory, the CDC says to use bottled water or bring tap water to a full rolling boil for 1 minute (3 minutes above 6,500 feet), then let it cool. DC Water’s May 2024 advisory after a 20-inch main break gives a useful real-world example of what utilities ask:

Discard drinks and ice made after the time the problem began.
If the water is discolored, run cold water until clear, then boil it.
If your home may have lead pipes or fixtures, run cold water for 2 minutes before boiling. If you can, filter it first with a filter certified to NSF/ANSI 53 for lead and NSF/ANSI 42 for particulates, then boil.
Use boiled or bottled water for drinking, brushing teeth, cooking, washing produce, baby formula, ice and pets.
Don’t rely on a home filter instead of boiling.

DC Water noted it had no information the water was actually contaminated. That’s typical. Most boil notices after main breaks are precautionary.

Our boil water advisory guide covers what’s safe room by room, including showers, dishwashers and pets.

How long will it last?

Advisories are lifted after testing confirms the water is safe. EPA Region 8 guidance says systems should collect total coliform samples upstream and downstream of the affected area and keep the advisory in place until two consecutive days of safe results. DC Water used the same two-day standard. In practice, that means most advisories last at least a couple of days after repairs. For what those bacteria tests measure, see coliform and E. coli in tap water.

Step 3: Deal with brown or discolored water

Discolored water is the most common thing residents notice after a break, even outside any advisory area.

Why it happens. NYC’s Department of Environmental Protection explains that a break, repair or nearby construction can stir up sediment, most often iron and manganese particles that have settled in the bottom of the mains under the street. Firefighting with hydrants can do the same thing. The water can look yellow, orange, red or brown.

Is it harmful? NYC DEP describes it as temporary and not harmful, but says residents should not drink obviously discolored water.

What to do:

Run the cold tap until the water is clear and cold before using it for drinking or cooking (NYC DEP).
Hold off on laundry, especially whites, until the water runs clear. NYC DEP warns that washing with discolored water can tint or stain clothes.
Give it time. Utilities often flush nearby hydrants to clear the mains. NYC DEP notes that how long it takes depends on the size of the mains in the area.
Call your utility if it doesn’t clear. NYC DEP says that if the problem shows up at only one tap, or clears after 5 to 10 minutes of running, it’s more likely a building plumbing issue.

Our guide to cloudy, brown or discolored tap water covers other causes and colors, and manganese in tap water explains that mineral in more detail.

Step 4: When service comes back

If your water was shut off for repairs, expect a few things when it returns:

Sputtering and air. Air trapped in the lines can make faucets spit and the water look milky. NYC DEP says air bubbles can make water look cloudy and that this isn’t a health concern. It clears quickly. If you hear rushing air when service is restored, NYC DEP says to leave the faucet on.
Low pressure at one faucet. Sediment can clog faucet aerators (the screens at the tip). NYC DEP notes you may need to clean the aerator. Unscrew it, rinse out the grit and reinstall it.
A chlorine smell. EPA guidance tells systems to disinfect and flush affected pipes as needed, following the AWWA C651 standard for disinfecting water mains. NYC DEP notes the chlorine odor from pipe cleaning goes away over time.

Flush for lead if you have lead pipes

NYC DEP warns that work on nearby pipes can temporarily raise lead levels in homes with lead plumbing. It gives a detailed flushing routine for homes with lead service lines after construction:

Remove the aerators from all faucets.
Run cold water at full force for 30 minutes from all faucets, including bathtubs, sinks and laundry tubs.
Put the aerators back.

NYC also recommends repeating that flush periodically for several months, plus running one faucet for five minutes each morning. Ask your own utility for its recommended routine. If you don’t know whether you have a lead service line, see how to find out if you have a lead pipe.

Step 5: After the advisory is lifted

Philadelphia Water says most boil water advisories don’t require flushing household pipes unless the utility tells you to. When flushing is advised, Philadelphia’s guidance typically includes:

Running all cold taps for at least 5 minutes
Making and throwing away three batches of ice from automatic ice makers
Running water softeners through a regeneration cycle
Running drinking fountains and water coolers
Changing refrigerator water filters

If the water still looks cloudy or discolored after the advisory lifts, Philadelphia says to run the faucet for a few minutes until it clears.

The CDC also notes that during any advisory, you shouldn’t drink or use water or ice from refrigerator dispensers, since they connect to your water line.

Quick checklist

During the break: - [ ] Check your utility’s map or alerts to see if you’re affected - [ ] If there’s a boil notice: boil or use bottled water, discard drinks and ice made since the problem began - [ ] Don’t drink discolored water; run cold until clear - [ ] Hold off on laundry while water is discolored

When service returns: - [ ] Let air clear from the lines - [ ] Clean faucet aerators if pressure is low - [ ] Flush cold taps, longer if you have lead pipes

After the advisory lifts: - [ ] Follow your utility’s flushing instructions - [ ] Dump ice-maker ice and replace fridge filters if advised

To see your utility’s EPA compliance record, including any past health-based violations, search your water system.