You need to be careful where you get your water from. This includes water for drinking, cooking, and brushing your teeth. Ask your health care provider about special care you should take. Use the information below as a guide.

Tap water is water from your faucet. It should be safe when it comes from:

• A city water supply
• A city well that supplies many people with water

If you live in a small city or town, check with your local water department. Ask if they test the water every day for the kind of germs that can give you an infection -- some of these germs are called coliforms.

Boil water from a private well or a small community well before you drink it or use it for cooking or brushing your teeth.

Running well water through a filter or adding chlorine to it does not make it safe to use. Test your well water at least once a year for coliform germs that may cause an infection. Test your water more often if coliforms are found in it or if there is any question about the safety of your water.

To boil water and store it:

• Heat the water to a rolling boil.
• Keep the water boiling for at least 1 minute.
• After boiling the water, store it in the refrigerator in a clean and covered container.
• Use all this water within 3 days (72 hours). If you do not use it in this time, pour it down the drain or use it to water your plants or your garden.

The label on any bottled water you drink should say how it was cleaned. Look for these words:

• Reverse osmosis filtration
• Distillation or distilled

Tap water should be safe when it comes from a city water supply or a city well that supplies many people with water. It does not need to be filtered.

You should boil water that comes from a private well or a small local well, even if you have a filter.

Many sink filters, filters in refrigerators, pitchers that use filters, and some filters for camping do not remove germs.

If you have a home water-filtering system (such as a filter under your sink), change the filter as often as the manufacturer recommends.

Chemotherapy - drinking water safely; Immunosuppression - drinking water safely; Low white blood cell count - drinking water safely; Neutropenia - drinking water safely

Cancer.Net website. Food safety during and after cancer treatment. www.cancer.net/survivorship/healthy-living/food-safety-during-and-after-cancer-treatment. Updated August 2021. Accessed May 29, 2024.

Centers for Disease Control and Prevention website. About home water treatment systems. www.cdc.gov/drinking-water/about/about-home-water-treatment-systems.html. Updated April 10, 2024. Accessed September 19, 2024.

Updated by: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.