Rainwater Harvesting

Thousands of gallons of water can be collected off your roof throughout the year, but plan to install your rainwater harvesting system in the late summer or fall to take advantage of the Pacific Northwest’s bulk of rain which falls from October to May.  It can be as easy as installing a rain barrel at a downspout or as involved as a complex cistern system.  Consider the PNW’s dry summer when sizing your system and plan for how the water will be used.  Storing and utilizing stormwater from your site can significant reduce your water bill.  In addition, stormwater diversion will assist with reducing drainage issues on your site, stormwater problems in your neighborhood, and help to conserve water.   

Rain Barrels   

Rain Barrel

Rain barrels are easy to install and a low-cost solution for rainwater harvesting.  Great for residential applications, rain barrels are compact, discreet, and can be installed individually or as several connected together.  Refer to King County’s list of locations around the greater Seattle area and online sources for purchasing rainbarrels or sources on how to make your own rain barrel.      

Rain barrels consist of the a barrel with a lid and screen to protect the water from insects, an overflow pipe, and spigot near the bottom of the barrel.  Rain barrels can be used individually or can be connected together to create a larger retention system.  Most typical rain barrels hold between 50-55 gallons of water.  If you plan to use the water from your rain barrel collection system for irrigation throughout the summer, it is recommended to connect several together to collect and store enough volume to last the entire dry season.         


Building a below ground concrete cistern. Auroville, India.

Cisterns have been used around the world for thousands of years and have recently become more commonly used in the Pacific Northwest.  Cisterns are designed to collect and store varying amounts of water from 200 gallons on upward.  They are available in many shapes, sizes and materials and can be stored either above or below ground.  Many premanufactured cisterns are made of fiberglass, galvantized steel with an interior liner, and stainless steel (typically cost prohibitive).  Other cisterns can be custom made on-site with concrete, masonry, and other materials.   

The water from your cistern can be used for irrigation or, if coupled with a filtration system, for domestic water use (check with your local building department).  If you plan to use the water collected from your roof for domestic water use, you will want to consider the type of roofing that you have installed on your home, for example metal roofing is the most effective and cleanest option for rainwater harvesting.  Visit Rain Wise with the City of Seattle or Tank Town to find out more information and to learn about types of pre-fabricated cisterns.       

Visit these helpful sites for more information:       

Rain Wise Installing a Cistern       

City of Seattle Public Utilities       

Contact H2D at 206-370-4762 or at heidi@h2d-llc.com if you have questions or are considering a rainwater harvesting system.


2 responses to “Rainwater Harvesting

  1. Well check this site out, it is amazing. It has info, system components and how to start rainwater harvesting.

  2. I hope that this article on Rainwater Catchment may help a few people. It basically explains how to add water pressure to your project for free and without electricity.

    Rainwater harvesting and water pressure

    It’s so simple, but works a dream at our Eco Resort.

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