Water Catchment on the Suburban Frontier

Reader Contribution by Jan Spencer
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Transformation work started on this quarter-acre suburban property in 2,000. The site is flat, good soil with good solar access. It’s in a suburban neighborhood; the house was built in 1956. The intention from the start was to do a permaculture makeover to take care of more needs closer to home.

For this blog post, I would like to describe my rain water catchment system, an intention from the start and first time ever for me.

Sizing a Rainwater Catchment System

Catch and store rain in the Pacific Northwest? That’s right. Its dry here in the summer. We can go two months with, essentially, no rain. The reasons for the system are partly for irrigation, drinking if I need to and “green preparedness..” The plastic for all these tanks is polyethylene and is food grade, made without chlorine.

Useful info: An inch of rain on 1,000 square feet comes out to about 550 gallons. Many suburban homes will have a roof of 2,000 square feet if not more. For a roof of 2,100 square feet, multiply 550 times 2, times 30 inches of rain, for example, and that comes out to 33,000 gallons. You can look at your water bill to gain a sense of reference.

I visited a retail tank store 40 miles away, that sold ag and water tanks. I went to the place in person, looked around and found two used tanks I was not told about on the phone. They are both oblong tanks that would have been mounted on the back of a flat bed truck. They are 1,600 gallons each and I paid very little for them, even delivered. I had to fix a leak on one of them.


Note that if you think you will save money with a rainwater system, that is not likely going to happen. If you have city water, like I do, it is priced so cheaply that the “value” of a full 1,600 gallon tank is about $5. So that’s a lot of tanks of water to pay off a new tank that can easily cost $500 to a thousand dollars depending on the size. Tank lifespan? With care, a tank will last over 20 years.

Siting and Roofing for Rainwater Catchment

Once delivered, mine had to be moved to their locations, close to downspouts in places that had less value for other uses. When empty, these tanks could be pushed by two people on wooden planks, like rails. When full, one tank weighs 13,300 lbs.

The front yard tank required the gutters to be reversed so they flowed towards the tank. I had to direct the water over a window, join up with another down spout and then into the tank. All the acqueduct material is off the shelf, simple vinyl downspouts. The back yard tank was a bit more complicated with a 90-degree turn, under a window and around a corner to the man hole. It was a thrill the first time it rained and I was there to see the trickle come into the tank.


Catchment surface: I started out with a regular asphalt shingle roof. A PhD chemist friend told me once that if a shingle roof is a few years old, there is little danger of contamination from the shingles. The shingles do catch a lot of dirt and some bird pooh. Water from these tanks is for irrigation purposes only and not direct ingestion.

Later, I re-roofed my house using galvalume standing seam metal. Very nice. Many sources strongly recommend galvalume. Its an alloy finish, it is not paint. The alloy is zinc and aluminum applied in an industrial process. The Texas Rain Water Handbook recommends galvalume if you want to drink the water. Of course, you still need to sanitize the water.

I installed another tank in about 2008. The new tank is 3,000 gallons, that’s eight feet in diameter and eight high, up to where side becomes top. That tank was bought new on line and catches water from the roof of a detached structure behind the main house which also has a galvalume roof. This tank, in combo with a Berkey ceramic gravity filter makes water great for off the grid drinking.


Using and Filtering Rainwater

To distribute the water, I run a hose from the tank to a 50-gallon barrel out in the garden. My garden area is not so much, so it’s simple to dip a watering can in the barrel and water. Its good to make a circular dike around plants, if possible, to contain the water where you want it. Soaker hoses that don’t need much pressure can work, too. Even the large tank produces only a 2- or 3-foot water “push” out from the end of a hose. I have my tanks up on blocks, about a foot off the ground.

Benefits from the tanks are numerous. It’s really educational in the summer to actually see the level of the tank go down as its used for irrigation. It’s a much more tangible way to understand what it takes to maintain a garden. That means it should create a new level of respect and care for resources used.

My total storage of close to 6,500 gallons will take care of my garden over a summer that is on the dry side. With our winters, the smaller tanks can fill up 5 or 6 times. The large tank maybe twice. In a crisis, is there water for both plants and people? That depends what time of year.

The only pre-filter of water entering the tank is a window screen. I have cleaned out the tanks after ten years and found the accumulated muck filled about one fifth of a 5 gallon bucket. No problem with bugs.


Home Economics on the Suburban Frontier

Catching rainfall is part of “home economics,” taking care of more needs closer to home. Home economics is part of a larger ideal of replacing some of the money economy with a home economy. When friends and neighbors are doing this and people work together, the scale can increase so more needs can be taken care of closer to home. There are a couple dozen others nearby also into life on the suburban frontier.

Of course, important to home economics and resilient living is to reduce other needs as well – food, energy, water and more as you can. Some people call it “downsizing” or “voluntary simplicity.” If enough people quit buying products that were not healthy for people and planet, those products might go away along with the companies that make them.

Catching rainwater is great fun. It connects a person directly to the real world. It makes for a more resilient home, along with home production of food, energy and whatever else can help replace the mainstream economy.


You can see many photos of my rain water system and other projects at my place near Eugene, Oregon, plus, galleries of nearby properties and permaculture sites elsewhere in the Northwest and beyond. Go to Suburban Permaculture for more information.

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