Buying a Home with a Rainwater Catchment System in Hawaii

If you’re purchasing a home in Hawaii with a rainwater catchment system there are actions you should take as a buyer to assess the system and to determine its level of functioning. If you’re unfamiliar with rainwater catchment but will soon be responsible for maintaining a catchment system, educate yourself about requirements for ensuring your water is safe and can be used in the ways you want to use it.

What is rainwater catchment in Hawaii?

Rainwater catchment is the capture of rainwater, most commonly in tanks, for household and landscape use. These systems are popular in regions of Hawaii where municipal water is not available. Catchment systems are popular among the environmentally conscious and folks who live off grid. An estimate 30,000 to 60,000 people in the state of Hawaii are dependent on rainwater catchment systems. The majority of people who rely on rainwater live on the Big Island in the Districts of Kau, Puna and Hamakua.[1]

Rainwater harvesting has been around for thousands of years. Cisterns are mentioned in the Old Testament and rainwater harvesting systems in the Middle East date back 5,000 years. Water shortages and water quality concerns continue to compel interest in rainwater catchment.[2]

What are the basic components of a rainwater catchment system in Hawaii?

The basic components of a rainwater harvesting system are the collection surface (often the roof), gutters, downspouts, pre-filtration systems or “first-flush” devices, storage tanks and sanitizing distribution systems. 

The filtration and treatment system should be certified. Devices are certified by organizations such as the National Sanitation Foundation (NSF), Underwriters Laboratories (UL) and the Water Quality Association (WQA). These certifications are good for the contaminants listed on the certification. You shouldn’t assume devices remove contaminants that are not listed. 

Is water collected through a catchment system in Hawaii safe?

When properly collected and treated, water provided by a catchment system is safe. 

When properly designed and with proper maintenance and water treatment, rainwater catchment systems can provide water that is odorless, pleasant-tasting and free of contaminants. Properly treated rainwater can be used for drinking, bathing, washing, flushing, laundry and gardening.[3]

When NOT properly collected and treated, water provided by a catchment system is NOT safe.

As one could guess, an improperly designed or poorly maintained catchment system can pose serious health risks. In Hawaii it is up to you — the owner of your system — to maintain your water source and use it appropriately. No government agency oversees the safety of your water in Hawaii. Problems caused by a poorly functioning water harvesting system are not always obvious, such as lead poisoning. A healthy adult may not become ill from drinking contaminated water but those who are more vulnerable to illness such as the elderly and infants can become deathly ill from drinking that same water.[4]

What if I’m buying a home in Hawaii with a rainwater catchment system?

If you’re buying a home in Hawaii with a rainwater catchment system it should be examined by a home inspector who is qualified to inspect rainwater catchment systems. The water should be tested by a certified lab. If you are a VA buyer your lender will require the use of a VA-approved water testing company. If you’re unfamiliar with catchment and will soon be the owner of a catchment system, get educated! The safety of your water depends on it.

What are some common hazards to the safety of my water in Hawaii?

Common water pollution hazards for rainwater catchment systems are shown below. This diagram comes from Guidelines on Rainwater Catchment Systems for Hawaii by Patricia S. Macomber of the College of Tropical Agriculture and Human Resources at University of Hawaii at Manoa. The guide contains useful information regarding water collection and storage, catchment system maintenance, water treatment and testing.   


Who can I hire to build a rainwater catchment system in Hawaii?

Several companies on the Big Island build and repair rainwater catchment systems and offer guidance to individuals wanting to build their own. As a real estate agent I’m unable to make specific recommendations. A few companies you may want to explore are Island Catchment Company, WaterWorks and Pool & Tank Specialists of Hawaii.

Island Catchment Company is located in Hawaiian Paradise Park. They design, build and repair catchment systems. They deliver water. They stock ultra-violet sterilization units, sediment filters and other replacement parts such as standard and customized tank liners, lamps, Quartz sleeves and ballasts. They sell metal tank roofs and polyethylene fabric covers. Call 808.982.8282 or email them.

WaterWorks has two locations — Hilo and Kona. WaterWorks was established in 1987 and offers locally manufactured water catchment systems. They stock multiple sizes of sedimentation and carbon filters, UV sterilization systems and replacement bulbs. For Hilo call 808.933.9111. For Kona call 808.322.2222. Contact them to request a quote.

Pool and Tank Specialists of Hawaii install catchment systems as well as swimming pools. They carry water tank liner replacements, dome canopies, covers and pumps. They have over 20 years of experience and guarantee their work for a year. Call 808.987.2533 or email them.


How do I get my water tested in Hawaii?

Testing catchment water will help assure the water is safe and determines actions that should be taken to make the water more suitable. Testing should be performed as part of your due diligence when purchasing a home with a catchment system. For a VA loan, water testing must be performed by a VA-approved company.

As an owner of a catchment system you can send your own sample to the lab but if water testing is performed for the purchase of a property being financed, the sample must be collected by an independent third-party. No interested party such as the buyer, seller, lender or real estate agent can collect the water sample.

The Hawaii Department of Health, State Laboratories Division publishes a List of Certified or Approved Water Laboratories. Two Hawaii-based water-testing companies on this list are AECOS Laboratory, Inc. and Food Quality Analysts, LLC.  Their staff collects the sample — usually from the kitchen faucet — and transports it to the lab.

AECOS, Inc. is a biological and water quality consulting firm located in the Hawaiian Islands. Their main office and laboratory facility are located in Kaneohe. Their laboratory conducts drinking water analyses, soil quality and other tests. Call 808.234.7770 or email them.

FQLabs is a full service independent testing laboratory serving Hawai‘i and the Pacific Rim since the 1860’s. They offer comprehensive microbiological and chemical testing of drinking water. Call 808.839.9444 or email them.


State of Hawaii Safe Drinking Water Branch

Call the State of Hawaii Safe Drinking Water Branch at 808.586.4268 if you have any questions regarding lab status and drinking water tests. 

Material presented in this article is drawn from three essential resources you should be familiar with in Hawaii if you’ll be installing or maintaining a rainwater catchment system:

  1. The State of Hawaii Department of Health Safe Drinking Water Branch
  2. University of Hawaii Sea Grant website
  3. Downloadable publication: Guidelines on Rainwater Catchment Systems in Hawaii

DISCLAIMER: Efforts have been made to ensure the information provided in this article is accurate but it’s essential to perform your own research when evaluating or enlisting a company to provide water catchment installation or testing services. Material shown here was collected from various websites, the content of which may change over time. Businesses change their services and offerings. New technologies and practices will evolve in regard to rainwater catchment system design and maintenance. As the owner of a rainwater catchment system it is up to you to ensure the quality of your water and to use that water appropriately.

[1] https://seagrant.soest.hawaii.edu/wp-content/uploads/2018/06/rainwater-catchment-hi_guidelines_2010.pdf

[2] https://seagrant.soest.hawaii.edu/wp-content/uploads/2018/06/rainwater-catchment-hi_guidelines_2010.pdf)

[3] https://www.arcsa.org/page/195

[4] https://seagrant.soest.hawaii.edu/wp-content/uploads/2018/06/rainwater-catchment-hi_guidelines_2010.pdf

DISCLAIMER: The information provided here, while deemed reliable, is gathered from third-party sources. It may contain inaccuracies. It is provided without warranty or guarantee of any kind. Interested parties must independently verify any information they deem material or important to their decisions. It is essential to perform your own research when enlisting a company to provide services. Material shown here was collected from various websites, the content of which may change over time. Businesses routinely change their services and offerings.

Copyright© Lisa A. Kramer, Ph.D. // All rights reserved // September 2021

Published by BiggerIsland.com

Aloha! I’m a real estate agent on the wonderful and amazing Big Island of Hawaii. I live up the hill from Keauhou Bay, just south of downtown Kailua-Kona. I love to help people. If I can be of assistance, get in touch.

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