Budgeting a Residential Rainwater System for Irrigation

Some Rules of Thumb

Every week, you'll need 1 gallon of water for every 2 square feet of annuals or turf that you want to irrigate. Natives need much less. 

Every week, your rooftop can collect about 1 gallon for every 2 square feet, on average in Georgia. 

The problem is, we don't get the same amount of rain every week, as you know. So how big a tank is ideal? It's a tough question to answer, since one part of the equation is predicting the weather for the next 10-20 years. Another part is predicting water rates for the next few decades. And finally, we need to predict watering restrictions and the outcome of the multi-state "Water War."

We have a modeling app, based on expected demand and rainfall rates. But a quick way to size the tank is to collect FROM a square foot of rooftop for every square foot of annuals or turf we want to irrigate, and size the tank for 1 gallon/square foot collected. 

Your rainwater system will cost about $4/gallon installed, plus the piping to route the water to the tanks, and an irrigation system to distribute the water. Add another $2/gallon for underground tanks. 

Reference Job: Residential Rainwater Harvesting

This job used 2 - 1750 gallon tanks, which is a good size for the irrigation area and rooftop.

This was the irrigation contractor's first rainwater harvesting job. We spend as much time as requested on-site, showing the installers how to do it right, and that everyone understands how it works. The technology isn't new, we just put things together in a different way.

The Intewa Purain filter fit great just below the manway. There's enough space to move past the the filter to get to the tank. The pump goes here also. We show the contractor how to pipe and wire it so that someone can access the tank through this same hole.

Burying the tanks.

We have found that homeowners like to know how much rainwater they are using. So we installed a meter

The finished product. Ready for the Tour of Homes.  

Time from first customer contact to fully installed: less than 4 weeks. 

Commissioning time: 15 minutes to connect pump to power and reset the circuit breaker.  Usually City of Atlanta water pressure is very high, but in this case, our rainwater pump was even better!

See if you can find it here.

Rainwater Harvesting Solves LA Drought?

If a blue collar community in Los Angeles County can find and afford to use rainwater to supply most of its needs, then really, nobody has any excuse.

http://www.yesmagazine.org/issues/cities-are-now/los-angeles-imports-nearly-85-percent-of-its-water