Rainwater Harvesting

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Rainwater Harvesting

Written by Master Gardener Homer Babbitt

If there was something you could do in your own backyard to help a butterfly, would you do it? If it improved the look of your flowerbeds, attracted beneficial insects, and was good for the environment, would you think about it? It’s an important question, and worth your consideration because the monarch butterfly needs your help.

The monarch is a Texas resident only three months of the year. It’s unique because it spends its entire life migrating. A new generation is born here every spring during the mont

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Are the words: drought, and water restrictions hampering your success in the garden? Are you waiting for summer with a mixture of anticipation and dread? There are several actions we can take to help reduce the impact of our dwindling supply of water, and the Master Gardeners of Parker County have spent a considerable amount of time researching and learning about them. Rainwater harvesting is just one of those alternatives which will be discussed here.

What is rainwater harvesting? In simple terms, it means taking the various steps necessary to capture and retain rain that falls on your property and using it wherever you need water. This might include water for livestock, wildlife, landscapes or even households.

The concept is certainly not new; we?ve been doing this for centuries. Those of you who grew up in a rural area as much as 50 years ago probably had a cistern that held rainwater collected from the roof of your house. As more modern methods of distributing water were developed, we got away from the practice. With the prolonged drought we?ve had the last couple of years; there is a renewed interest in collecting rainwater. Several southwestern states, including Texas, have been promoting the harvesting of rainwater as a way to provide an additional source of water that otherwise would not be utilized. There are two basic methods for harvesting rainwater. The simple method catches the water and distributes it immediately. The more complex method includes a means of storing water for use at a future time. Both methods require two things ? a catchment area, such as the roof of your house or other structure, and a way to distribute water to an area where it?s needed. The simple method can be used by almost anyone. All it requires are gutters around your house and a long extension on the downspout to deliver rainwater to your landscape bed. The bed should be constructed with a berm or small hill around the lower side to retain water and prevent runoff. It?s also important to select appropriate plants, since they must be able to survive short periods of excess water as well as longer periods without water.

The more complex method requires use of a tank to store water during periods of heavier rainfall so it can be used at a future time when rain is not sufficient to meet your needs. The tanks can be as simple as a 55 gallon barrel under your gutter or as elaborate as a 15,000 gallon metal storage tank with filter, water purifier, and pump to supply your entire household. Whichever method you choose depends on where you live, how much space you have, how much water you need, size of your catchment area and your budget.

For people living in an urban area, it may not be practical to consider a large tank on your property, but almost everyone


has space for a barrel. Two or three 55 gallon barrels placed around your house will provide water for a small vegetable garden or house plants. You will be amazed how much better they will do with rainwater compared to either well water or water from a municipal water supply. A 55 gallon barrel completely rigged out to catch water from your gutter downspout will cost around $100 -$125, and is a great way to get started. Not only that, once you pay for the barrels, the water is free!

For those living outside the city on small acreage or ranchers who may need a supplemental source of water; a larger tank is an ideal way to go. Here are a few guidelines which will help you determine the potential for collecting rainwater. First, do a quick calculation of the size of your home or other building you plan to use for your catchment area. You need to know the total square footage of the building. The pitch of the roof doesn?t matter, just size of the building. Multiply the total square feet by 0.6, to get the number of gallons of water you can collect for each inch of rainfall. For example, if your house is 2,000 square feet, you can collect 1,200 gallons of water for each inch of rain.

Second, consider the type and size of tank to be used for holding the water. Tanks come in a wide variety of sizes and materials, including plastic, wood and metal. Typically, plastic tanks are the cheapest; and metal tanks are the most expensive. A medium sized plastic tank of 1,500 -2,500 gallons will cost about $.65 to $.80 per gallon, with the unit cost declining as the size gets larger. Metal tanks are about 2 or 3 times that much. The final piece in the puzzle is how to get water from the tank to the place where you need it. If you?re lucky, gravity will do the work for you. If not, you may need to elevate the tank, install a pump, or carry it by hand. Again, a lot depends on your budget and how much potential you have for collecting and using rainwater.

There has been a lot of discussion recently about our dwindling water supply. Prolonged drought and increased growth and development have put heavy demands on our existing sources of water. In many urban areas, from 30-50 percent of total water used during summer months is for landscape irrigation. Reducing that demand by using rainwater will benefit everyone. Harvesting rainwater not only makes use of a valuable natural resource, it also has many other benefits as well. It will save you money and reduce flooding, erosion and contamination of surface water with sediments, fertilizers and pesticides in rainfall run-off.

Additional Resource:  How to Build a Rainwater Barrel

Have a question? pcmgatx@gmail.com

Parker County Master Gardeners, Texas A&M AgriLife Extension