Public Drinking Water Systems
Naegleria fowleri has caused deaths associated with using disinfected public drinking water supplies in Australia 1 and Pakistan 2 and an untreated, geothermal well-supplied drinking water system in Arizona 3. The largest amount of experience in managing Naegleria fowleri-contaminated water supplies is in Australia, which had multiple deaths in four states during the 1970s and 1980s that were linked to swimming or having other nasal exposure to contaminated drinking water. The infections were linked to piping drinking water overland, sometimes for hundreds of kilometers, that resulted in the water being heated and having low disinfectant levels. These conditions allowed the water and pipes to become colonized by Naegleria fowleri. Several water systems in the states of Western Australia and South Australia continue to monitor regularly for Naegleria fowleri colonization in drinking water distribution systems 4. Experience gained in managing Naegleria fowleri contamination of specific water systems has prevented further infections in Australia since that time.
Recommendations for Users of Naegleria fowleri-Contaminated Drinking Water Systems
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 in 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 [PDF - 12 Pages]."
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.
You cannot get infected from drinking water contaminated with Naegleria. You can only be infected when contaminated water goes up into your nose.
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.
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.
Western Australia Department of Health. Amoeba Response Protocol [PDF - 12 Pages]. 2013.
National Health and Medical Research Council, National Resource Management Ministerial Council, Commonwealth of Australia, Canberra. NRMMC Australian Drinking Water Guidelines Paper 6 National Water Quality Management Strategy [PDF - 1,244 Pages]. 2011.
- Dorsch MM, Cameron AS, Robinson BS. The epidemiology and control of primary amoebic meningoencephalitis with particular reference to South Australia. Trans R Soc Trop Med Hyg. 1983;77(3):372-7.
- Shakoor S, Beg MA, Mahmood SF, Bandea R, Sriram R, Noman F, Ali F, Visvesvara GS, Zafar A. Primary amebic meningoencephalitis caused by Naegleria fowleri, Karachi, Pakistan. Emerg Infect Dis. 2011 Feb;17(2):258-61.
- Marciano-Cabral F, MacLean R, Mensah A, LaPat-Polasko L. Identification of Naegleria fowleri in domestic water sources by nested PCR. Appl Environ Microbiol. 2003;69:5864-9.
- Puzon GJ, Lancaster JA, Wylie JT, Plumb IJ. Rapid detection of Naegleria fowleri in water distribution pipeline biofilms and drinking water samples. Environ Sci Technol. 2009;43:6691-6.
- Yoder JS, Straif-Bourgeois S, Roy SL, Moore TA, Visvesvara GS, Ratard RC, Hill V, Wilson JD, Linscott AJ, Crager R, Kozak NA, Sriram R, Narayanan J, Mull B, Kahler AM, Schneeberger C, da Silva AJ, Beach MJ. Deaths from Naegleria fowleri associated with sinus irrigation with tap water: a review of the changing epidemiology of primary amebic meningoencephalitis. Clin Infect Dis. 2012;1-7.