Filtering tap water: Many, but not all available home water filters remove Cryptosporidium. Some filter designs are more suitable for removal of Cryptosporidium than others. Filters that have the words "reverse osmosis" on the label protect against Cryptosporidium. Many other types of filters that work by micro-straining also work. Look for a filter that has a pore size of 1 micron or less. This will remove microbes 1 micron or greater in diameter (Cryptosporidium, Giardia). There are two types of these — "absolute 1 micron" filters and "nominal 1 micron" filters. The absolute 1 micron filter will more consistently remove Cryptosporidium than a nominal filter. Some nominal 1 micron filters will allow 20% to 30% of 1 micron particles to pass through.

NSF-International (NSF) does independent testing of filters to determine if they remove Cryptosporidium. To find out if a particular filter is certified to remove Cryptosporidium, you can look for the NSF trademark plus the words "cyst reduction" or "cyst removal" on the product label information. You can also contact the NSF at 789 N. Dixboro Road, Ann Arbor, MI 48105 USA, toll free1-877-867-3435, fax 313-769-0109, email info@nsf.org, or visit their Web site at www.nsf.org/certified/DWTU/. At their Web site, you can enter the model number of the unit you intend to buy to see if it is on their certified list, or you can look under the section entitled "Reduction claims for drinking water treatment units - Health Effects" and check the box in front of the words "Cyst Reduction." This will display a list of filters tested for their ability to remove Cryptosporidium.

Because NSF testing is expensive and voluntary, some filters that may work against Cryptosporidium have not been NSF-tested. If you chose to use a product not NSF-certified, select those technologies more likely to reduce Cryptosporidium, this includes filters with reverse osmosis and those that have an absolute pore size of 1 micron or smaller.

Package and Label information for purchasing water filters:

Note: Filters collect germs from water, so someone who is not HIV infected or immune impaired should change the filter cartridges. Anyone changing the cartridges should wear gloves and wash hands afterwards. Filters may not remove Cryptosporidium as well as boiling does because even good brands of filters may sometimes have manufacturing flaws that allow small numbers of Cryptosporidium to get in past the filter. Selection of NSF-Certified filters provides additional assurance against such flaws. Also, poor filter maintenance or failure to replace the filter cartridges as recommended by the manufacturer can cause a filter to fail.

If you drink bottled water, read the label and look for this information:

Bottled water labels reading "well water," "artesian well water," "spring water," or "mineral water" do not guarantee that the water does not contain crypto. However, water that comes from protected well or protected spring water sources is less likely to contain crypto than bottled water or tap water from less protected sources, such as rivers and lakes.

Home distillers: You can remove crypto and other germs from your water with a home distiller. If you use one, you need to carefully store your water as recommended for storing purified water.

Other drinks: Soft drinks and other beverages may or may not contain crypto. You need to know how they were prepared to know if they might contain crypto.

If you consume prepared beverages, look for drinks from which crypto has been removed:

Juices made from fresh fruit can also be contaminated with crypto. Several people became ill after drinking apple cider made from apples contaminated with crypto. You may wish to avoid unpasteurized juices or fresh juices if you do not know how they were prepared.