What to Know About Boil-Water Notices

Houston has become the latest U.S. city to issue a boil-water advisory after a Sunday morning power outage at a treatment plant caused water pressure to fall below the level required by the Texas Commission on Environmental Quality. The situation in the Texas city affects at least 2.2 million residents’ water supply.

“We believe the water is safe but based on regulatory requirements when pressure drops below 20 psi we are obligated to issue a boil water notice,” tweeted the Houston Mayor’s Office on Sunday.

The city is asking folks to boil water for three minutes before consumption, and reminding people to avoid using chilled water and ice from any appliances connected to the waterline, such as a refrigerator. City officials are currently testing the water across the city to see if anything grows, they said at a press conference. The Texas Commission on Environmental Quality hopes to lift the notice by early Tuesday morning.

Here’s what to know about boil-water notices in the U.S.:

What causes a boil-water notice?

Boil-water notices are put in place when an event has potentially contaminated a public water system. This can include circumstances like power outages, storms, floods, water-line breaks, well problems, the loss of water pressure, or loss of disinfection.

Read more: America’s Clean Water Crisis Goes Far Beyond Flint. There’s No Relief in Sight

Can you shower or brush your teeth during a boil-water notice?

While a boil-water notice is in effect, the CDC advises people to boil all water before its use in any capacity, including bathing. Individuals should be careful not to swallow any water when they shower. Sponge baths are recommended for children.

Residents can brush their teeth with boiled water, or bottled water can also be used as an alternative, according to the New York State Department of Health (NYSDOH).

All water, even water that has passed through a filter, should be boiled before use.

How long do boil-water notices usually last?

Boil-water notices typically last somewhere in the range of 24 to 48 hours, though this can vary depending on the reason why the ordinance went into effect.

Are boil-water notices becoming more common?

While there is no official count of the exact number of boil-water notices issued in 2022 and years past, this year there have been boil-water advisories in cities including Detroit, Austin, and Laredo, Tex. In Jackson, Miss., alone, Mississippi Today reports, the city has issued 20 boil water notices just since Sept 15. (The city also has a legacy of poor water infrastructure that caused it to experience weeks without any reliable running water, a circumstance even worse than a boil-water advisory.) Meanwhile, approximately 240,000 water-main breaks happen every year, disrupting water systems for millions of Americans.

Part of this prevalence is likely due to the United States’ aging water infrastructure and extreme weather events, one 2020 paper in the Journal of Public Health Management and Practice noted. As climate change drives more extreme weather, that second factor may play an increasing role. Hurricane Ian, for example, caused communities in Lee County, Fla,. to undergo a boil-water notice in October.

Read more: The Mayor of Jackson, Miss. Had a ‘Radical’ Vision for His City. The Water Crisis May Have Put It Out of Reach

What happens if you drink tap water during a boil-water notice?

Boil-water advisories are put in place because water in the affected area either contains, or has the potential to contain, germs that could make people sick. If you do drink unboiled tap water during a boil-water notice, the NYSDOH says, the chances of becoming ill are still slim—but it’s possible.

Infants, children, the elderly, and those with compromised immune systems or chronic illness are the most at-risk. During these situations, one Texas doctor told ABC News, water quality can be similar to that of straight flood water, making it risky to consume it in any capacity.

If you feel ill after drinking water during such an advisory period, you should contact your healthcare provider. Symptoms of water-borne illness can include diarrhea, nausea, vomiting, cramps, and possibly fever.