Sunday, March 24, 2013

Home Rooftop Rainwater Harvesting

Arizona allows and encourages the practice of collecting roof runoff for reuse on your property.  Check whether your state allows this via Google. Some do, some don't, based on their basic water law, i.e. who owns the rain. Not joking -- I was listening to a radio station while driving through Utah and it sure sounded like Utah owns the rain that falls within the state boundaries....

108 gallon stack barrels (53 gallons each) by Arid Solutions
Collections tanks and cisterns can be expensive and obtrusive, but there are ways to reduce the cost and the visual impact. I bought tanks about 10 years ago, before they got really expensive. I wanted to add another recently and discovered that I couldn't afford another one of the type I have.  The model had more than doubled in cost! 
This is a 200 gallon barrel in a backyard.
Metal dome in the top center is just a bowl I turn over to keep it from becoming a birdbath. We added the gutters for less than $100. Dear Husband did the work, materials were from Home Depot. 

I thought I'd provide a few references and ideas for you handy-people who want to have a little more clean water for your home use. If you live near a Farm, Ranch or feed store, you can usually pick up a 30 to 50 gallon barrel that can be easily converted for rainwater harvest storage for under $50.  I like using rainwater on some of my plants because our groundwater is alkaline. Even when using containers and potting soil, I can't grow blueberries without rainwater -- too alkaline! Kills them fast.

When deciding how large a system to install, consider your rain seasonality, roof size and budget.  Some sites have calculators that allow you to plug in your rainfall and roof size, but essentially for every 1000 SF of roof and 1/2 inch of rain, you have potential to collect 300 gallons of water.  The first little bit of rain may be needed to wet the roof, especially with standard shingles, but after that, it's yours. My 200 gallon barrel has a diverter that goes to an old boxwood hedge. It is lush, so I need to re-think that and put it to better use!

My favorite DIY is using corrugated metal culverts.  It's definitely work, because you need a concrete pad, but the cost is manageable in bites as you go along.  A 46 inch culvert, 4 feet high will store 300 gallons of water. A good, frost-resistant commercial tank will cost you about $600 for the same capacity. You can probably do better using this method or if your area has prolonged freezes (or are a glutton for punishment) and need it to be below ground, this one.

I've seen people around here hide the metal with paint, stucco or stucco walls.  When we walk the dog in the nearby riparian park, we can see into some backyards, where most people put their tanks. What variety!  We see some that are house-colored, some big black 2500 gallons jobs, others are the 55 gallon blue ones.  People are good about mosquito screens, so we've seen no increase of bugs as the harvesting has increased.

In areas with an urban runoff problem, rooftop capture can be a great method to reduce the runoff, especially if the entire neighborhood decides to harvest their rainwater.  It can reduce your water bill or electric bill when you buy or pump less water. Worst case, add a little Clorox (maybe run it through a coffee filter) and you can drink it!


  1. This was really a best technique for rain water harvesting at home level. which was very beneficial to use rain water for house hold purpose.Thanks for sharing such a wonderful blog with us.
    rain water harvesting system

  2. One of the best techniques to get rain water harvesting at home. Rain water increase the water resources and water treatment.

  3. Water is a hot commodity, and it’s great that it could be recycled for other uses. With the number of environment issues our world is facing nowadays, this practice should be encouraged to promote sustainability. Thanks for sharing your tips and techniques!

    Sharon Strock @ StormChamber®

  4. Great post.Harvesting rain water is a great step.
    Harvesting rain water has many benefits. Everyone should take this initiative for the betterment of the society