Medical Nutrition Therapy: Water Safety Guidelines
If you have a suppressed or decreased immune system you need to be careful about the water you drink. This handout will help you to decide if the water you are using is safe. It will also help you to learn how to make your water safe to drink.
In most cases, tap water from a city water supply or municipal well is thought to be safe if the water is disinfected. However, not all communities disinfect their public water supplies. In this case, it should probably not be assumed to be safe. We suggest checking with your local community to see if they disinfect the water. If they do not disinfect, then the water should brought to a rolling boil for one minute before drinking. Large amounts of water can be boiled and then stored in your refrigerator.
The bacterial content in bottled water can vary greatly. Not all bottled water is safe for neutropenic patients or patients with low white blood cell counts.
Bottled water is thought to be safe if it has been treated by:
- Reverse Osmosis
- Filtered through an absolute 1 micron or smaller filter
You can find out how your bottled water has been treated by looking on the bottle label or on the company website. The International Bottled Water Association (IBWA) also has records about water filtration treatments for certain brands. Contact the IBWA at www.bottledwater.org or
1-800-928-3711 to learn more about bottled water.
Filters must be designed to remove coliforms and Cryptosporidium. The filters listed below have been approved:
- Reverse Osmosis Filter
- Filter with absolute pore size of 1 micron or smaller
- National Sanitation Foundation Standard #53 for cyst removal filter (www.nsf.org or 1-800-673-8010)
The water filter should be installed right before the water tap. All manufacturer guidelines must be followed. Portable filters, such as BritaÒ or PurÒ or water from your refrigerator do not filter for bacteria. These types of systems will not improve the quality of water. They may be used along with one of the above safe water supplies to improve the flavor of water.
Although testing for coliforms and Cryptosporidium is done yearly, well water is not assured to be safe for patients with suppressed immune systems. Non-chlorinated water is not believed to be safe.
Water that has been boiled for one minute, filtered as described above, or bottled using an approved method, is thought to be safe.
Ice machines do not meet filtration standards. All ice should be made by hand using water from a safe water supply.
If you are a UW patient and have more questions please contact UW Health at one of the phone numbers listed below.
2880 University Avenue
Madison, WI 53705
UW Health West Clinic
451 Junction Road
Madison, WI 53717
UW Health East Clinic
5249 East Terrace Drive
Madison, WI 53718
The information provided should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Any duplication or distribution of the information contained herein is strictly prohibited.
Last Updated: 08/06/2012
Copyright © 04/21/2011 University of Wisconsin Hospitals and Clinics Authority. All rights reserved. Produced by the Department of Nursing. HF#377
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