21 Aug Rainwater Systems Done Right

Yesterday evening at Treehouse green home improvement store, Design-Build-Live brought in Chris Maxwell-Gaines of Innovative Water Solutions Chris gave a great comprehensive presentation on good design for rainwater systems. Chris had his start in rainwater collection while in the Peace Corps in South America where he learned to live with a 200-gallon tank of rainwater for all his indoor water needs. Since then he’s had 10 years of experience running a rainwater engineering company, so his knowledge on this topic is broad and deep. Here’s some of the advice he passed along last night:

Why Rainwater Harvesting? A few reasons to put rainwater collection into your life and business include:

• Regional watershed systems can’t support large human populations.
• It counteracts the extreme runoff situation you create with large amounts of impervious cover (i.e. buildings, streets, parking lots) in urban areas.
• Rain doesn’t always fall in the right place to replenish urban water supplies. (Take the Onion Creek Halloween flood, for example, which did nothing to help fill up Lake Travis!)
• Localized rainwater collection reduces dependence on massive, centralized water treatment and distribution systems which have miles of pipe that leak quite a lot.

Some Rainwater Don’ts – Believe it or not, people have tried all these things that he definitely doesn’t recommend.

• Don’t use clear pipes, or tanks. Sun plus rainwater equals algae!
• Don’t string many small tanks together with lots of connecting pipe. That’s a lot of potential leakage!
• Don’t bury tanks that weren’t designed to go in the ground. They’ll collapse!
• Don’t DIY completely on your own. Pay for an hour or two of professional advice and avoid major pitfalls!

Components of a Good Rainwater System

• Roof – Almost any type of roof surface works for irrigation water. For potable (drinking quality) metal, clay, or tile work best.
• Gutter screens to keep out leaves and debris.
• Tank inlet filter
• First-flush reservoir with ball valve (need about 10 gal per 1,000 square feet of collection surface)
• Pump system
• Backflow prevention device (especially for systems connected to city water systems)
• Tank gauge to show how much water you have
• Storage – good tanks are usually metal, polyethylene, or fiberglass. You can also put storage bladders into crawl spaces in the foundation of a building.
• Treatment – For potable water, a sediment filter, carbon filter and disinfection system (typically UV light) are necessary.

Size of System

The best thing to do to size your system is to do the maximum you can with your budget and space you have available for storage. Currently, City of Austin rebates are $1/gallon for pressurized rainwater systems and $0.50/gallon for non-pressurized. Rebates tend to change, or disappear, so get them while the getting is good!

NOTE: Thanks to Mike Kaiser at Treehouse for finding the notes I left at the store and reading them to me over the phone so I could finish this blog!