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Rainwater Catchment Project

What is Rainwater Catchment?

Rainwater catchment is the capture of rainwater, most commonly in barrels or tanks, for household, landscape or commercial use. With proper design, maintenance and water treatment, a rainwater catchment system can provide water that is free of contamination, soft, clear and odorless and can be used for drinking and other daily needs (Macomber, 2010). However, improperly designed and/or maintained rainwater catchment systems may pose a serious health risk (e.g., introducing a water-borne illness) that can be exacerbated in those with compromised immunity (Pathak and Heijnen, 2005). Rainwater catchment is also used to manage stormwater runoff using earthen berms/swales to direct rainwater to drainage areas or holding ponds, decreasing the likelihood of unwanted flooding. Captured rainwater can also be used in commercial or industrial applications, such as cooling towers. Rainwater catchment reduces the use of ground water (well water) and/or surface water and associated costs to consumers. In some areas without municipal water service, water catchment may be the only source of fresh water available.

Why is Sea Grant interested in Water Catchment?

When used appropriately, water catchment can provide a cost-effective, reliable, safe, fresh water source that reduces the use of and conserves ground or surface water reserves, benefitting the people of Hawai'i and improving the stewardship of the state's water resources.

Water catchment also conserves energy via the "Energy-Water Nexus." The Energy-Water Nexus describes the relationship between water use and energy use. In short, it takes energy to collect, pump, treat, purify and deliver fresh water to users. Further, the process of energy generation and use often consumes water; thus savings in one results in savings in the other.

For information on past workshops and trainings click HERE

For information on PathoScreen Water test kits click HERE

To check the availability of water quality test kits (for personal, household, school, or non-profit organization use) click HERE

Useful Links

State of Hawaii Department of Health Safe Drinking Water Branch:

Rat Lungworm. The Daniel K. Inouye College of Pharmacy. University of Hawaii at Hilo:

The American Rainwater Catchment Systems Association:

Centers for Disease Control and Prevention (CDC), Drinking Water, Private Water Systems:

References Cited

Macomber, Patricia S.H. Guidelines on Rainwater Catchment Systems for Hawaii. College of Tropical Agriculture and Human Resources, University of Hawai’i at Manoa. 2010.

Pathak, Namrata and Heijnen, Han. Rainwater Harvesting and Health Aspects-Working on WHO Guidance. World Health Organization and the Australian Agency or International Development. 2005.


Funding for this project was provided by the United States Department of Agriculture (USDA), National Institute of Food and Agriculture (NIFA) grant award 2014-46100-22345. Website:

The American Rainwater Catchment Systems Association (ARCSA) provided significant in-kind support to the project through ongoing collaboration including the participation and expertise of ARCSA Education Coordinator Mr. Tim Pope. Website:

Professor Susan Jarvi, Director, Pre-Pharmacy Program and Associate Professor, University of Hawai'i at Hilo, graciously allowed the use of unpublished data and other content related to her research on rat lungworm disease in community workshop presentations.

Some project elements were conducted through contractual services via Tri-Ed Services. We thank Ms. Patricia Macomber of Tri-Ed Services for her exceptional contributions therein and for her ongoing spirit of collaboration and generosity of expertise with regard to rainwater catchment.

Ms. Chantal Chung, Dr. Mary J. Donohue, Mr. Matthew Gonser, Dr. Robert Howerton, Ms. Patricia S. H. Macomber, and Mr. Timothy Pope conducted project activities.

We thank the Hawai'i Sea Grant Communications Unit for online support of project activities.