Public Drinking Water Systems

The recommendations below are intended specifically for people served by a water system that has been determined to be contaminated with Naegleria fowleri. If you have not heard an announcement that your water system is affected by Naegleria fowleri, please follow our general recommendations for prevention.

If Naegleria fowleri is suspected to be in a municipal drinking water system, the water utility may raise disinfectant levels and flush the system to get rid of Naegleria fowleri. There is normally a layer of scum or biofilm coating pipes in water systems and homes. If Naegleria fowleri has colonized a water system, it might be found in the biofilm layer. It is possible that raising disinfectant levels could lead to some of that biofilm coming loose in the water system or a household and being flushed through the system or home. As a general precaution, the following recommendations are provided for residents on water systems raising their disinfectant levels and flushing the system. They are adapted from the Western Australia Department of Health’s “Amoeba Response Guidelines.“

Remember, you cannot be infected with Naegleria fowleri by drinking contaminated water. When water systems have the disinfectant raised, the water may have a strong chemical taste or smell, but your water utility will be working to make sure it still meets drinking water standards.

Since Naegleria fowleri infects people when water containing the ameba enters the body through the nose, it is critical to prevent water going up the nose.

• DO NOT allow water to go up your nose or sniff water into your nose when bathing, showering, washing your face, or swimming in small hard plastic/blow-up pools.
• DO NOT jump into or put your head under bathing water (bathtubs, small hard plastic/blow-up pools) – walk or lower yourself in.
• DO NOT allow children to play unsupervised with hoses or sprinklers, as they may accidentally squirt water up their nose. Avoid slip-n-slides or other activities where it is difficult to prevent water going up the nose.
• DO run bath and shower taps and hoses for 5 minutes before use to flush out the pipes. This is most important the first time you use the tap after the water utility raises the disinfectant level.
• DO keep small hard plastic/blow-up pools clean by emptying, scrubbing, and allowing them to dry after each use.
• DO use only boiled and cooled, distilled, or sterile water for making sinus rinse solutions for neti pots or performing ritual ablutions.
• DO keep your swimming pool adequately disinfected before and during use. Adequate disinfection means:
  • Pools: free chlorine at 1–3 parts per million (ppm) and pH 7.2–7.8
  • Hot tubs/spas: free chlorine 2–4 parts per million (ppm) or free bromine 4–6 ppm and pH 7.2–7.8
  • If you need to top off the water in your swimming pool with tap water,
    DO place the hose directly into the skimmer box and ensure that the filter is running.
    DO NOT top off by placing the hose in the body of the pool.
  • For further information on operating swimming pools, visit CDC’s Healthy Swimming website.

These recommendations make common sense but are not based on any scientific testing since the low number of infections makes it difficult to ever show that they are effective. They are based on experience with previous infections caused by using Naegleria fowleri-contaminated tap water.