Giardia contamination in water: this article explains Giardia cyst contamination in drinking water and we review alternative treatment, sterilization, or giardia removal methods used to make drinking water safe from giardia contamination.

How to Treat or Purify Giardia-contaminated Water to Sanitize it For Drinking

• Chemical contaminants:
  
  If your water supply has become contaminated by pesticides, heavy metals, or other chemicals, disinfecting the water will not correct those unsafe conditions.
• Protozoan contaminants:
  
  Chlorine and iodine are good disinfectants against bacterial contamination (probably among the most common water contaminants) but studies cited in this article have shown that these are not effective against certain contaminants in water such as toxic chemicals, Cryptosporidia (Cryptosporidium parvum) , and Giardia.
  Also seeReferences or Citations .
• Filtration and boiling
  
   are additional steps that can address these microorganisms. Activated charcoal can remove some chemical contaminants but has limited life and capacity.

This article series outlines methods to purify or sanitize drinking water in an emergency following a disaster such as an earthquake, flood, or hurricane. Some of the water treatment or water purification methods discussed are also used for regular non-emergency water sterilization as well.

A companion article DRINKING WATER EMERGENCY SOURCES describes possible sources of drinking water that may be useful in emergency conditions.

Advice for Dealing with Giardia cysts in Drinking Water

InspectAPedia.com reader Sharon Ross is a New York City resident, a Riverkeeper member and a MENSA member, who for health reasons has collected references and treatment information about dealing with Giardia cyst contamination in drinking water. This article is in draft form and is incomplete. Contact Us with corrections or suggestions.

Giardia cysts also survives the amounts of chlorine in municipal water treatment. Dr. Herman Bueno, a Parasitologist I conferred with reported in 1994 that people with AIDS were dying of Giardia in hospitals because of their weakened immune systems. We would not recommend that anyone with a compromised immune system eat raw vegetables without sufficient sterilization to kill parasite cysts.

Ceramic Filters for Giardia cyst & Cryptosporidium Removal from Drinking Water

There are ceramic giardia and cryptosporidium filters that can be used to filter tap water so that cysts will not be ingested by drinking it. The company that I have bought my ceramic filter from is Duff company, though there are other companies that also carry them. The ceramic filters are "absolute" and if used properly, remove the cysts 100 percent.

Well water, or even municipal water when it delivered inside of some buildings, contains high levels of sediment that causes water filters to clog quickly. Thus water filters may need cleaning as often as every few days, making filtration to remove giardia a labor intensive solution. But it beats being exposed to cysts which may be present in some drinking water supplies.

Eventually ceramic water filters wear down from the constant scrubbing and they have to be replaced. Even with the work involved, we recommend them for anyone with a compromised immune system.

See FILTERS for DRINKING WATER PURIFICATION for details of various water filter options.

Charcoal Water Filters for Giardia cyst & Cryptosporidium Removal from Drinking Water

Granulated charcoal filters do not work. Environmental activist, Robert F Kennedy Jr. has been aware of Giardia contamination of our water and we think that he was trying to get a filtration system that would remove cysts built for NYC. The problem was the cost - by some estimates over a billion dollars.

Whole House Filtration Systems for Giardia cyst & Cryptosporidium Removal from Drinking Water

There are now both point of use reverse osmois systems (photo at left) and whole house filters or RO systems that remove parasite cysts. A sample proposal for a whole house reverse osmosis (RO) water treatment system is provided

at Example of an Equipment Design for Water Filtration for Giardia. A reverse osmosis whole house filter system including a large storage tank can be installed if you own your own home and have a place to put it.

Also available is a filter attachment to remove nitrates as well, since nitrates can be a problem in some areas. I am sending you is an attachment with a link.

Sato Iwasa of Pure Water Express was very helpful and knowledgeable in discussing whole house water treatment options.

Duff Company provides ceramic giardia cyst filters.

OPINION: Our beaches are no longer safe for the immune compromised and maybe not for others as well. Billions of tons of raw sewage are being dumped into Long Island Sound because we do not have the sewage treatment plants to handle it. This can be confirmed by another New York environmental organization, "Riverkeeper".

That means that waste from third world immigrants who are carriers of parasites from India, the middle east, China, and Latin America and other countries where parasites are endemic is being carried by the currents to the ocean beaches that New Yorkers swim in. According to Dr. Bueno, cysts take at least three days to die in ocean water so they can be still viable and be ingested.

Examples of U.S. Sources of Giardia Infection

You do not have to travel to a foreign country to be exposed to Giardia cysts, though it has been our experience that many physicians still believe that you do, and if you complain of parasite related symptoms they still ask you if you have left the country.

Giardia Contamination Around New York City

In New York there are huge storm drain runoff pipes that run into Little Neck Bay. Some of them are near Alley Pond Environmental center and you can speak to the director of the center about them. I had taken a wrong turn on a trail in Alley Pond park leading from the center when encountered a terrible stink and I came one of "storm" drains which are storm drains no longer and there is a constant flow of sewage from them.

There was a hoard of seagulls circling overhead and the filth was pouring into the waters leading to the sound. When we (Ross) asked the director about why this was happening, since it was a sunny dry day with no rain in sight, he told me that the storm drains are in operation constantly because we do not have the facilities to handle all of the raw sewage.

On the opposite side of the storm drains running into Little Neck Bay are Westchester beaches, though few doctors would make the connection if someone complains of exhaustion weakness, diarrhea, MS like symptoms and abdominal pain.

Dr. Tennenbaum, an infectious disease specialist reported that they now treat empirically for Giardia if the person has been in endemic areas in our country i.e.: vacationing in Maine, and is exhibiting symptoms. because Giardia is so difficult to find. We do not know if New York City is considered an endemic area for Giardia.

Eating out in some restaurants can also cause problems. Giardia is endemic to the USA and can be carried and spread from anyone born here who has been infected. Further, restaurant workers who have lived-in countries where parasites like entameoba histolytica are common may be a potential source of parasites.

Some people who suffer from a compromised immune system no longer eat out in restaurants.

Safe foods? According to Dr. Amin, parasite cysts cannot withstand the freeze/thaw cycle, so am safe with ice cream (I am not considering bacteria that can withstand freezing) and food taken out from a restaurant that is frozen, thawed and then re-heated.

Ross recommends that anyone wash their hands thoroughly when they come home and turn public faucets on and off with clean paper towels.

Difficulty in Diagnosing & Treating Giardia Infection

When a person first becomes infected with Giardia, stress and irritable bowel may be suggested by more than one physician.

Parasite cysts are often difficult to spot under the microscope and tests for them can manifest negative results when a person is really infected. Dr. Bueno reported that the US army tests GI's 8 times if they complain of parasite type symptoms and the results are negative. Dr. Amin also said that two stool samples might not be sufficient to determine if a person is infected.

Use of UV light, Vinegar, or Chlorine for Giardia cysts ?

Reader Opinion about vinegar's effectiveness on Giardia

As for vinegar as a method of killing giardia cysts, it is highly acidic and it breaks down the walls of the giardia cysts, if it is used full strength. Dr. Omar Amin, of "Parasitology Center " in Tempe, Az confirmed this. [WARNING: authoritative sources confirming the safety of this approach have not been obtained.]

Here is a representative reader comment: "I have battled an immune disorder and I had been very ill with intractable Giardia because of my condition. I do not eat raw produce now unless I sterilize it. Right now, I use distilled white vinegar.

I submerge vegetables in pure vinegar for 25 minutes but more porous vegetables have a vinegar taste when I am done.

I have ceramic giardia filters on my tap water now and I was thinking that if I could use a peroxide solution, and then rinse off the peroxide in fresh, giardia free water, I would not have to deal with a vinegar taste."

Really? Please see VINEGAR for PRODUCE or WATER DISINFECTION for an authoritative summary of the efficacyof vinegar as a disiinfectant.

UV doesn't kill cysts, according to Dr. Amin and I have seen websites that advertise it to kill giardia which is very misleading. it will kill Giardia trophozoites but the real concern for drinking water is the cysts, since it is the cysts from stool that appear there.

Really? you might want to take a look at "A-class" vs "B-class" UV treatment systems as their ability to deactivate parasitic cysts varies. - Ed. ]

Chlorine does kill cysts in high enough amounts, the amount that one would find in a swimming pool, amounts not suitable for drinking and I was told by another parasitologist that I have conferred with, that the cysts would take about 20 minutes to die in a chlorinated swimming pool.

A-class UV light treatment systems combined with chlorine treatment has been used for treatment of Giardia infected water. But

Watch out: failure to keep the UV system clean, to match the light intensity and size and treatment time to the flow rate of water through the system, or other snafus can prevent UV from working effectively even where it is considered most-effective on non-pathogenic bacteria in the water supply. Ed.

Example of an Equipment Design for Water Filtration for Giardia, Equipment Costs

Pre-filter Water Filter for Sediment Removal

Optional: install a plastic sediment filter 1-1/2" model to remove sediment, $289 includes shipping, ref: www.purewaterexpress.com/wholehouse.htm#3a removes dirt before the water supply enters the reverse osmosis component, providing insurance protection of the RO filter against water main work upstream (or a private well water source containing sediment) sending massive debris into the water treastment system.

Reverse Osmosis RO Treatment Unit Cost

Compact II-2: special high flow membrane, daily production 250 gallons minimum, $1,548 plus shipping from Perris, CA, reference: www.purewaterexpress.com/wholehouse.htm#9.

See REVERSE OSMOSIS WATER TREATMENT for details of reverse osmosis water purification systems and alternative RO products.

Other reverse osmosis, filter, ceramic filter and water treatment products are listed at the end of this article.

Post Reverse-Osmosis RO Water Treatment Processing Equipment Options

1. 165 gallon storage tank, float switch,1 HP re-pressurization pump, low pressure cutoff safety switch, $2,122 plus shipping from MN
2. 1-1/2 cubic foot reverse flow acid neutralizer, $342, 1 cubic foot calcite $60, plus shipping from MN, restores pH of RO water close to neutral, ref: www.purewaterexpress.com/wholehouse.htm#7
3. Post RO polishing carbon +UV 20” Big Blue $1,049 includes shipping, ref: www.purewaterexpress.com/wholehouse.htm#5 Carbon makes delicious tasting water, UV protects against potential bacterial growth over time in the storage tank

Research on Giardia & Cryptosporidium Parasitic Cysts as Contaminants in Drinking Water

• Atherton, F., C. P. S. Newman, and D. P. Casemore. "An outbreak of waterborne cryptosporidiosis associated with a public water supply in the UK." Epidemiology and Infection 115, no. 01 (1995): 123-131.
• Betancourt, Walter Q., and Joan B. Rose. "Drinking water treatment processes for removal of< i> Cryptosporidium</i> and< i> Giardia</i>." Veterinary parasitology 126, no. 1 (2004): 219-234.
• Flanagan, P. A. "Giardia--diagnosis, clinical course and epidemiology. A review." Epidemiology and Infection 109, no. 1 (1992): 1.
• Fraser, G. Graham, and Kenneth R. Cooke. "Endemic giardiasis and municipal water supply." American journal of public health 81, no. 6 (1991): 760-762.
• Hashimoto, Atsushi, Shoichi Kunikane, and Tsuyoshi Hirata. "Prevalence of Cryptosporidium oocysts and Giardia ysts in the drinking water supply in Japan." Water Research 36, no. 3 (2002): 519-526.
• Hayes, Edward B., Thomas D. Matte, Thomas R. O'Brien, Thomas W. McKinley, Gary S. Logsdon, Joan B. Rose, Beth LP Ungar et al. "Large community outbreak of cryptosporidiosis due to contamination of a filtered public water supply." New England Journal of Medicine 320, no. 21 (1989): 1372-1376.
• Jephcott, A. E., N. T. Begg, and I. A. Baker. "Outbreak of giardiasis associated with mains water in the United Kingdom." The Lancet 327, no. 8483 (1986): 730-732.
• Kent, George P., JOEL R. Greenspan, Joy L. Herndon, Lynne M. Mofenson, J. A. Harris, Thomas R. Eng, and Hetty A. Waskin. "Epidemic giardiasis caused by a contaminated public water supply." American journal of public health 78, no. 2 (1988): 139-143.
• LeChevallier, MARK W., William D. Norton, and Ramon G. Lee. "Giardia and Cryptosporidium spp. in filtered drinking water supplies." Applied and Environmental Microbiology 57, no. 9 (1991): 2617-2621.
• LeChevallier, Mark W., William D. Norton, and Ramon G. Lee. "Occurrence of Giardia and Cryptosporidium spp. in surface water supplies." Applied and Environmental Microbiology 57, no. 9 (1991): 2610-2616.
• Levine, W. C., W. T. Stephenson, and G. F. Craun. "Waterborne disease outbreaks, 1986-1988." MMWR. CDC surveillance summaries: morbidity and mortality weekly report. CDC Surveillance Summaries/Centers for Disease Control 39, no. 1 (1990): 1-13.
• Mac Kenzie, William R., Neil J. Hoxie, Mary E. Proctor, M. Stephen Gradus, Kathleen A. Blair, Dan E. Peterson, James J. Kazmierczak et al. "A massive outbreak in Milwaukee of Cryptosporidium infection transmitted through the public water supply." New England journal of medicine 331, no. 3 (1994): 161-167.
• Rose, Joan B., Charles P. Gerba, and Walter Jakubowski. "Survey of potable water supplies for Cryptosporidium and Giardia." Environmental Science & Technology 25, no. 8 (1991): 1393-1400.
• Rose, Joan B., Charles N. Haas, and Stig Regli. "Risk assessment and control of waterborne giardiasis." American journal of public health 81, no. 6 (1991): 709-713.

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