Rainwater Collection Systems

Written by
Steve Troy
Published on
July 14, 2023 at 9:43:44 AM PDT July 14, 2023 at 9:43:44 AM PDTth, July 14, 2023 at 9:43:44 AM PDT

Rainwater Collection Systems

“If you only do one thing, collect rainwater...”
-Bill Mollison

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The importance - the need - for more rainwater harvesting systems, both residential and commercial, feels more and more critical with every news article about water shortages, every video of forest fires breaking all-time records, with news of floods, erosion and droughts. Every year, more and more cities, farms, towns, and gardens run out of water. Rising temperatures rapidly increase this momentum toward desertification.

Water, Water, Everywhere...

The amount of water on Earth is almost constant and has recycled over and over again throughout history. It's possible that we sometimes drink the same water a dinosaur drank! 80% of the earth's surface is water, 97% of the earth's water is salt water in seas and oceans. Of the 3% fresh water, only about 1/3 (1%) is available for drinking - the rest is frozen in polar ice caps. At least 2 gallons of water goes down the drain while we wait for it to get cold or hot. It typically takes about 400 gallons of water to grow enough wheat to make a two-pound loaf of bread, 50 gallons to produce one chicken egg, 4000 gallons for a kilo of hamburger, 1011 gallons for one gallon of milk, and an astonishing 4543 gallons for a kilo of chocolate.1

More People, Less Water

Each new day means more people to feed, more potable water demand, and less irrigation water to produce enough crops. By 2050, scientists estimate 70% more food will be needed to feed this ever-increasing population. An expected increase in that number comes from more income translating into a 40% increase in meat consumption.2 (Remember stat above that it takes 4000 gallons of water to produce 2.2 pounds of hamburger.)

As this need for water increases, overlooking one of our largest sources - rain - looks more and more foolish. When most hear the term "rainwater harvesting," they imagine a big rain barrel or storage tank. A normally less expensive but more effective method however, uses the ground to nurture living, mulch basin "sponges." The soil itself can become the water reservoir. Brad Lancaster coined the term we use here, -Planting the Rain- and eloquently describes these methods in his books and talks.3 Using rain catchment systems increases moisture in the soil which prevents evaporation, encourages deep root growth, and enables surface plants to act as living pumps that bring that moisture back up to the surface as needed. Greywater systems easily tie into these same mulch basins. Slow Water irrigation systems can also help this process.

We started using rainwater way back in the early 1950's, started promoting and selling greywater and rainwater systems at Open Circle in Garberville in the early/mid 1970's, then at our Real Goods stores in Willits, Ukiah, and Santa Rosa starting in 1978, and in our Real Goods mail order catalog, starting in 1980. We worked with Art Ludwig, one of the world's foremost experts on greywater systems, quite a bit when he was first getting started, sold hundreds of his books and referred hundreds of customers to him. We now have almost 400 gallons of rainwater storage at the Boulder office site, in use here for more than 20 years.

We were one of the only companies promoting and selling rainwater and greywater (aka gray water and grey water) systems in the '70's, but now those systems are much more established with lots of great resources. That niche seems currently filled without need for our help. The use of both rainwater and greywater for irrigation however, still seems in need of innovative development and marketing. We're focusing on both now with Sustainable Village.

Most drip emitters require at least 10 psi, many 25 psi. Our irrigation systems and products only need 1 - 2 psi and work really well with gravity systems. When used in subsurface systems, they could become a key to creating a truly sustainable and regenerative agriculture. Here's an inexpensive, simple product that almost anyone could use to get started - our Gravity Irrigation Kit.

See more on our website:
Rainwater Irrigation

"In the future, wars will not be ignited by the assassination of kings and dignitaries, but by the scramble for water." 1

More information:
The relationship between heat and soil moisture studied - Climate Action


  1. Water World, Nature.com: Water World | Eyes on Environment | Learn Science at Scitable
  2. Global Water Governance in the Twenty-First Century
  3. CASE STUDY: drought resistant farming in Africa Brad Lancaster, Zephaniah Phiri Maseko