Boiling kills germs but does not remove chemicals

Boiling tap water makes it safer to drink by killing most bacteria, viruses, and parasites that cause illness. However, boiling does not remove chemical contaminants like lead, chlorine, pesticides, or nitrates. If your tap water contains these chemicals, boiling will concentrate them rather than reduce them. Whether boiling is enough depends on what is actually in your water—which you can find out through a water test.

The safest approach is to know what contaminants your water contains before deciding whether boiling alone is sufficient. If you have never tested your tap water, boiling is a reasonable precaution for germs while you arrange a test. If a test shows chemical contamination, boiling alone will not fix the problem.

Key Takeaways

  • Boiling kills bacteria, viruses, and parasites but does not remove lead, chlorine, pesticides, nitrates, or other chemical contaminants.
  • You can request a free water test from your local water utility or purchase an inexpensive test kit to find out what is in your tap water.
  • If boiling is your only treatment option and your water contains chemicals, a pitcher filter or faucet filter removes some (but not all) chemicals and works alongside boiling.
  • Boiling water for one minute at a rolling boil kills most harmful germs; at high altitude (above 6,500 feet), boil for three minutes instead.

What boiling actually removes from tap water

Boiling works by using heat to kill living organisms. A rolling boil for one minute will kill most bacteria, viruses, and parasites that cause waterborne illness—including E. coli, salmonella, hepatitis A, and giardia. This is why boiling is recommended after water main breaks, flooding, or when a "boil water" notice is issued by your utility.

Boiling does not work on chemicals because heat does not break them down or remove them from the water. Lead, arsenic, nitrates, chlorine, and pesticides remain in the water after boiling. Some chemicals, like chlorine, may evaporate slightly if you leave water sitting uncovered for 24 hours, but this is not a reliable treatment method.

How to find out what is in your tap water

Your water utility is required to test tap water regularly and provide you with a water quality report, sometimes called a Consumer Confidence Report. You can request this report for free by calling your local water department or visiting their website. The report lists which contaminants were detected and at what levels.

If you want more detailed information or do not trust the utility's report, you can purchase a water test kit from a hardware store or online retailer for $20 to $100. These kits test for common contaminants like lead, bacteria, nitrates, and pH. For the most thorough results, send a water sample to a certified laboratory—your local health department can recommend one and costs typically range from $50 to $300 depending on how many contaminants you test for.

The correct way to boil water for drinking

Bring water to a rolling boil—vigorous bubbling across the entire surface—and maintain that boil for at least one minute. At high altitudes above 6,500 feet, boil for three minutes instead, because water boils at a lower temperature in thinner air and needs longer to kill germs effectively.

After boiling, let the water cool before drinking. Do not cover the pot while it cools if you want chlorine to evaporate, but cover it if you want to prevent dust or insects from falling in. Once cooled, boiled water can be stored in a clean, covered container in the refrigerator for up to three days.

When boiling alone is not enough

If your water test shows chemical contamination and boiling is your only option, you can add a pitcher filter or faucet-mounted filter to reduce some chemicals. Pitcher filters (like Brita or PUR) remove chlorine taste and some lead, but not all contaminants. Faucet filters are similar. Neither type removes all chemicals, so check the product label to see which contaminants it targets.

For more complete chemical removal, a whole-house filter or reverse osmosis system under the sink is more effective but costs more to install. If you rent and cannot install permanent equipment, a pitcher filter is a practical temporary step while you arrange to move or contact your landlord about water quality.

Special situations: when you must boil tap water

Your water utility will issue a "boil water notice" when contamination is detected or after a water main break. During these notices, boiling is the standard precaution and should be used for drinking, cooking, and brushing teeth. Follow the utility's specific instructions—some notices require boiling for one minute, others for three minutes depending on the contaminant.

Boil water notices are temporary and are lifted once the utility confirms the water is safe again. You will receive notice when the order is lifted, usually through local news, the utility's website, or a phone call. Once lifted, you can return to using tap water normally.

Common mistakes when boiling water

The most common mistake is not boiling long enough. A gentle simmer is not enough—the water must reach a rolling boil and stay there for the full minute (or three minutes at high altitude). Another mistake is covering the pot while boiling if you want chlorine to evaporate; covering traps the chlorine inside.

Do not assume boiling removes all contaminants. If you have lead pipes or know your water contains chemicals, boiling will not solve that problem. Finally, do not store boiled water for more than three days in the refrigerator, as it can become contaminated again if stored longer or in an unclean container.

Frequently Asked Questions

Does boiling remove chlorine from tap water?

Boiling does not actively remove chlorine, but some chlorine may evaporate if you leave water uncovered for 24 hours. If you want to remove chlorine taste quickly, a pitcher filter works faster. Boiling itself does not eliminate chlorine.

Is it safe to boil water in a microwave?

Yes, microwaving water until it boils kills germs the same way stovetop boiling does. Use a microwave-safe container and boil for at least one minute. Be careful when removing the container, as the water will be very hot.

Can I boil water from a well instead of a municipal supply?

Boiling kills germs in well water but does not remove chemicals like nitrates or arsenic. Well water should be tested annually by a certified laboratory because wells are not regulated like municipal supplies. If your test shows contamination, boiling alone may not be safe.

What if I do not have access to boiling equipment?

If you cannot boil water, a pitcher filter or bottled water are alternatives for chemical contaminants. For germ contamination during a boil water notice, contact your local health department or utility for other options—some communities provide bottled water during notices.

How long can I store boiled water?

Store boiled water in a clean, covered container in the refrigerator for up to three days. After three days, bacteria can regrow even in boiled water. If you need water longer than that, boil a fresh batch.