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Information on PathoScreen™ Water Test Kits

The following is for the PathoScreen™ using the WhirlPak® Fecal Bacteria Water Test Kit only. These kits provide an indication as to the quality of water tested via the presence or absence of fecal bacteria. The kits do not test for other disease causing organisms (virus, protozoa, nematodes, etc.). As contamination by fecal bacteria indicates a compromised water system, home test kits may be a first step to diagnosing contamination.

Water Test Kit Instructions

Sample Water Test Kit Results

Frequently Asked Questions of Sea Grant Extension

The following FAQs are for the PathoScreen™ using the WhirlPak® water test kit only.


These kits provide an indication as to the quality of water tested via the presence or absence of fecal bacteria.  The kits do not test for other disease causing organisms (virus, protozoa, nematodes, etc.). As contamination by fecal bacteria indicates a compromised water system, home test kits may be a first step to diagnosing contamination.

How does this test work? “Gut” (fecal) bacteria in the test kit consume the media and produce hydrogen sulfide as a by-product. Iron in the media reacts with hydrogen sulfide and turns the media black.

Why should we test our water? Water catchment systems may be contaminated from many sources including animals that may carry and/or transmit disease such as birds, rodents, snails/slugs and geckos/lizards. These vectors (disease transmitters) can contaminate water with bacteria that may cause illness. Infants, elderly and people with compromised immune systems are at a higher risk for illness than healthy adults, but it is possible for anyone to become ill from contaminated water. Wind can also blow contaminated soil and/or debris onto the catchment surface and conveyance systems.

My test came back positive. What should I do now? Decontaminate the whole system. You may find the CTAHR brochure “How to Decontaminate and Maintain Your Catchment System” helpful.

I left the test kit longer than 72 hours. Are the results still valid? No. Results observed after 72 hours may not be accurate. All media solution will eventually turn black. Dispose of the used kit as directed in the Test Kit Instructions and test again using a new kit.

How often should I test my water? At minimum, test your water whenever there is a change in your system such as a change in water odor or color, after installation of a new treatment system or component, after you decontaminate or treat your existing system or if you suspect you have contaminated water. When you know your treatment system is working properly, test regularly to confirm water quality—as an example: at least every six months.

How can I get my water tested? 1) Do it yourself with a water test kit; or 2) bring or send a sample to a certified lab.

What water quality variables should I be testing for? Most catchment users are concerned with disease causing organisms. As contamination by fecal bacteria indicates a compromised water system, they are most commonly tested for. Simple, inexpensive home test kits may be a first step to diagnosing contamination. Heavy metal contamination may also be a concern; lead may be a problem in homes built before 1978. Copper in very high levels can be toxic. Acidic rain leaches copper from copper piping often staining tubs and sinks with a blue/green tinge. Other testing may be needed for your specific circumstances.

Can I test for everything? No single test identifies all potential water contaminants.  Seek advice from an expert to identify the most appropriate testing for your unique circumstances.


Important notice: Users of chemicals such as household bleach for water treatment do so at their own risk. Most of these products are not labeled for use in rainwater catchment systems. Use of a commercial product as a biocide for sanitation purposes is subject to the limitations, restrictions, precautions, and directions given on the product label.

Disclaimer: The information contained herein is subject to change or correction. Procedures described should be considered as suggestions only. To the knowledge of the author, the information given is accurate as of January 2015. Neither the University of Hawai‘i at Mānoa, the UH College of Tropical Agriculture and Human Resources, the UH Sea Grant College Program, the United States Department of Agriculture, the agencies providing funding for printing, nor the author shall be liable for any damage or injury resulting from the use of or reliance on the information contained in this publication or from any omissions to this publication. Mention of a company, trade, or product name or display of a proprietary product does not imply approval or recommendation of the company or product to the exclusion of others that may also be suitable. The views and recommendations contained in this document are the views and recommendations of the author, not of the Hawai‘i Department of Health or the University of Hawaii Sea Grant College Program. Because many variables affect the quality of water generated by a rainwater catchment system, the Hawai‘i Department of Health does not endorse the concept that water of drinking-water quality may be achieved or maintained in all instances through compliance with the recommendations contained in this or other documents.

Revised September 9, 2015