The Ultimate Guide to Boil Water Advisories

Boil water advisories are put in place by public-health authorities when there’s a risk that your drinking water may be contaminated. Understanding why these alerts happen, and what to do when one is issued, is key to protecting your health and avoiding water borne illnesses.

What is a Boil Water Advisory?

A boil water advisory means that the drinking water supply may be compromised by harmful bacteria, viruses, or parasites. When such microorganisms get into your tap water, they can cause gastrointestinal problems like diarrhea, vomiting, stomach cramps, and other infections. By raising awareness through an advisory, authorities hope to prevent these illnesses before they begin.

When are Boil Water Advisories Issued?

These advisories are typically triggered when water-quality tests show signs of microbial contamination, or when infrastructure issues make contamination more likely. Common causes include:

• A broken water main or pipe that allows outside (and possibly contaminated) water to enter the system.

• Equipment or treatment failures at a water plant.

• Natural disasters or heavy flooding that disrupt the distribution system or allow surface-water intrusion.
  When the integrity of the system is compromised, the risk of harmful pathogens entering the supply goes up.

What Should You Do During a Boil Water Advisory?

When your local authority issues a boil water advisory, here are the key steps you should take:

1. Boil water prior to use. Bring water to a rolling boil (where large bubbles continuously rise) for at least one minute, then allow for the water to cool before using. Some guidance suggests boiling the water for longer if you’re at higher elevation.

2. Use boiled (and cooled) water or bottled water for: drinking, making ice, brushing teeth, cooking, washing produce, and dish-washing (unless you’re using a dishwasher with a sanitizing cycle).

3. Avoid swallowing unboiled tap water—including water from the shower, unless your local authority says it’s safe for that specific use.

4. Use a certified water filter rated to remove microbiological contaminants (bacteria, viruses, protozoa) if you’re concerned that boiling may not be sufficient or convenient. Many point-of-use filters exist that are tested for microbial removal. 

   • Make sure the filter is certified for microbial reduction (e.g., NSF/ANSI 53/58 or similar standards) or explicitly states it removes bacteria/viruses/cysts.

   • If you’re using a filter during an advisory, follow the manufacturer’s instructions closely—including any pre-treatment steps (like flushing) and maintenance (cartridge changes).

   • Even when using a filter, many authorities still recommend boiling if possible Filters can be a useful supplement, especially when boiling isn’t practical (for example during power outages).

5. Stay tuned for updates from your local water utility or public-health department. The advisory will remain in effect until testing confirms that the water meets the required safety standards.

How Long Do Boil Water Advisories Last?

The duration depends on the issue at hand. If the contamination source is quickly identified and remedied, like a minor pipe break, then the advisory might only last a few days. But when the problem is more severe (e.g., widespread infrastructure damage, flooding, or persistent microbial intrusion), it may take weeks or even months for all tests to clear and the advisory to be lifted.

How to Stay Informed About Boil Water Advisories?

It is important to stay informed about boil water advisories in your area to protect yourself and your family. You can sign up for alerts from your local public health department or water utility, monitor local news sources, and follow updates on social media. Being proactive and prepared can help you respond quickly to any advisories that may affect you.

Remember, boil water advisories are issued to protect your health and safety. By understanding what they are, how they are issued, and what steps to take during an advisory, you can stay informed and prepared to respond effectively. 

Sources:

Microbiological Effectiveness of Disinfecting Water by Boiling in Rural Guatemala

A meta-analysis of public compliance to boil water advisories

Boil Water Advisories as Risk Communication