Local Hero: Hawaii's Guru of Water Catchment- Trisha Macomber
by Doug Pushard

Who You Going To Call?

You have questions on your rainwater catchment system and need some answers quick. Questions like, "How do I know it's safe to drink the water? How do I test my water? What do I test for? Is it okay to swim in my catchment basin?"

If you live in Hawaii, you are lucky. You have Trisha Macomber to turn to. She retired from the University of Hawaii in the department of Natural Resources and Environmental Management as an Educational Specialist. But she put in many programs still in use and was the Click and Clack of rain catchment systems in Hawaii. She has been the liaison to the public since 2000 specializing in rainwater systems and spends her time answering questions like those above (i.e. Yes, these are real questions and the names have been removed to protect the guilty), giving seminars, updating the website, hand delivering information and providing guidance to local builders and new residents on designing new systems.

Why does Hawaii need a full-time rainwater person you might wonder; especially since most of Hawaii averages over 100 inches (254 centimeters) of rain a year? At Hilo International Airport, which averages about 126 inches (320 centimeters) of rainfall annually, only 2.65 inches (6.7 centimeters) fell in May of 2005. And just over 2 inches (5 centimeters) fell during the same period in Pahoa in Lower Puna. Hawaii is blessed with lots of annual rain, but also has spells of drought. Additionally, in some rural areas there is no municipal water at all and drilling a well through hard, volcanic rock would be prohibitively expensive, so hauling water in or rainwater collection are the only sources of water.

Information tallied in late 2004 by the Fire Department shows that approximately 17,900 Big Island households are not served by a municipal water system. With an average of 2.8 people per household, that means more than 50,000 residents -- nearly a third of the Big Island's current population -- have a big stake on the whims of the weather.

Ironically, central Puna, with more than 8,000 homes on catchment, averages better than eight feet (2.44 meters) of rain per year, enough to keep storage tanks full most of the time. But without water conservation, such as limiting laundry and minimizing other uses, even a few weeks without rain can leave residents with empty or low tanks. The Puna and Ka'u areas have the largest percentage of residents on catchment estimated at 75 percent and 43 percent, respectively.

So rainwater catchment is critical to a lot of people in Hawaii. In fact, it is a way of life! Trisha Macomber got interested professionally in rainwater systems in 1999, when a colleague asked her about leptospirosis. It was a serious heath problem at the time but there was no public information for those using rainwater as their water supply.

So Trisha, a biologist with a masters in public health, authored the Guidelines on Rainwater Catchment Systems for Hawaii (PDF). This excellent guide covers not just the health issues of systems but also how to build a system as well as how to store rainwater to keep it clean and healthy. Since its publication in 2002, over 13,000 hardcopies have been distributed and thousands more have been downloaded from the web. She has been called the Big Island’s “guru” of water catchment.

Besides Trisha’s passion for rainwater systems, she and her husband enjoy reading, playing with their cats and dogs and volunteering. They have been on the island of Hawaii for 26 years and Trisha brought her first house with a rainwater catchment system in 1981. Her Hawaiian husband, Ed, grew up using catchment systems.

Free Rainwater Harvesting Advice for Beginners

Trisha is amazed at the current growth spurt in Hawaii and the resulting number of new catchment installations. She offers potential new users the following advice.

  • Read the guidelines
  • Ask lots of questions
  • Think about preventive control and health issues before starting
  • Buy a tank with a solid cover

And for those lucky enough to be on the Big Island, email or call her if you have any questions. She remains excited about the all the new developments she is seeing in harvesting rainwater systems but would like to see more information and products in the area of complete home point of entry UV systems, integrated whole house water catchment systems, and on first flush devices.

Trisha Macomber, a local hero, to those in Hawaii and beyond. Mahalo iâ `oe
(mah hah' loh (y)ee (Y)AH' oe)
for all your efforts to get more folks interested and aware of how to catch and harvest rainwater effectively and safely.

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