Rainwater harvesting

Rain water harvesting has been in practice for centuries throughout the world to supply water for household, landscape, and agricultural uses.

In the past, rain water collection methods were crude and expensive. The advent of poly tanks and ease of PVC pipe plumbing has made rain water harvesting easy and inexpensive. As water is becoming precious in drought-prone areas, and groundwater becomes polluted by the use of chemical fertilizers, rain harvesting is becoming a necessity.

We’ll cover the basics of harvesting rain water for your home: for gardening as well as drinking and other household purposes.

A rain water harvesting system

Our first rainwater system

When I moved to Austin, Texas it was clear that water collection is necessary for gardening due to Austin’s sporadic low rainfall and extended hot summer months. I came to know about the City of Austin’s rain barrel sale and rebate program for rain water harvesting.

I decided to work with fellow master gardeners to learn about types of tanks, PVC pipes and plumbing and put together a rainwater harvesting system. The picture above shows a house roof water collection system. Based on this guide I built a system in my backyard with two poly tanks of 1550 gallons capacity in a suburban housing development. For aesthetic reasons, the tanks are low-profile and situated below the fence line so they are not visible from outside.

It is not difficult to put together the system yourself to save expensive labor charges. Plumbing with PVC pipes is easy as it does not require soldering. I built confidence with this project, and taught others through seminars and workshops.

Rainwater collection for Austin’s Zilker Botanical Garden

I then approached the City of Austin to build a rain water collection exhibit at the Zilker Botanical Garden, and developed a proposal and budget which showed that the city could reduce costs to the Water Conservation department by funding a permanent exhibit rather than conducting expensive, biannual home tours.

The city approved and funded the project, and with help from fellow Master Gardeners, we built the system. The Zilker exhibition system was built with metal, fiberglass, and poly tanks and rain barrels. All four tanks were interconnected with a compact 1hp compact electrical pump, without a bleeder tank or water level indicator. This system was completed and ready for public display in February 2005.

This voluntary effort resulted in a permanent, year-round public exhibit, and saved tax dollars.

The Travis County Master Gardeners Association (TCMGA) had built two 2500 gallon black poly tank rainwater harvesting systems for the greenhouse. Later, it became necessary to add more tanks to handle additional water usage at the greenhouse. This project was completed by adding two green poly tanks to the existing system with minimum effort by interconnecting all four tanks and adding a water-level indicator.

Advantages of rain water harvesting

  • Rain water is free
  • Pure and soft
  • Neutral pH
  • Free from corrosion
  • No “scale” effect
  • Appliances last longer
  • Plants thrive well
  • No need for water softener
  • Reduces soil erosion
  • Saves money!

Rain water is typically used for gardening, but it can also be made potable for drinking by three-stage filtering that includes a UV filter for bacteria. In the Texas hill country, where there are few municipal water sources, people are installing 20-40,000 gallon tanks with UV filters for household use, which is cheaper than deep well water.

Rain water collection is even being introduced in urban high rise buildings and shopping centers. For example, the Bank of America Tower in New York has a rain water collection system.

Getting started with rainwater harvesting in Austin

Rain water collection has become popular in Austin, as the water conservation department offers rebates of up to $500.00 for residential systems.

For further details, call the City of Austin’s water conservation department at 512-974-2199 or visit the city’s rain water web site.

Gani Garden can also help plan your rainwater harvesting system. Contact us for more information

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