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Safe drinking during cancer treatment
Why You Need to Be Careful with Water
During and right after your cancer treatment, your body cannot protect itself against infections. Tiny germs can be in water, even when the water looks clean. You will need to be careful where you get your water from. This includes water for drinking, cooking, and brushing your teeth. Ask your doctor or nurse about special care you should take.
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 (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, the 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.
How 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 up this water in 3 days (72 hours). If you do not use it in this time, throw it out.
The label on any bottled water you drink should say how it was cleaned. Look for these words:
- Reverse osmosis filtration
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 filters you may take on camping trips do not make water safe to drink.
If you have a home water-filtering system, ask the company you got it from how to keep the filter clean. Tell them that your body cannot protect itself against infections.
Most water-filtering systems can make the water safe only by adding chlorine to the water supply.
National Cancer Institute. Nutrition and cancer care (PDQ). November 13, 2011. Accessed May 19, 2012.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.