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Texas Rainfall Catchment ℠
Rainwater Harvesting Systems Design and Installation Services
Capture, store and use the best water you can get ®
Each inch of rainfall drops 1,240 gallons on a 2000 square foot roof. To approximate the amount of rainwater falling on your roof, multiply the square footage of your roof footprint(including porches and garage) by .62 to get your gallons per inch of rain. Tip: if you don't know the square footage of your roof footprint, substitute your house square footage.
It depends mainly on the annual rainfall in your area, but also on the "runoff efficiency" of your roof. A conservative estimate would be 85% efficiency due to evaporation, splashing, and roof surface smoothness. So a realistic collection amount from that inch of water on a 2000 square foot roof is 1,054 gallons. Multiply the square footage of your roof by .527 to get a conservative estimate of your collection potential or use our rainwater calculator.
Water used for foundation plantings and gardens can be cut in half by using drip irrigation and mulch instead of sprinklers or sprayers. St. Augustine turf needs about an inch of water a week to stay green. Several varieties of Bermuda need only half that amount. Buffalo grass needs almost no supplemental watering once established, but it needs a lot of sun. Consider replacing your sunnier areas of St. Augustine with Buffalo grass, and creating mulched areas in the shadiest spots planted with native or adapted low water use plants. You can probably reduce your turf water use by half or better.
Rain clouds form in the sky when water vapor in the atmosphere cools and forms droplets. These droplets also contain dissolved nitrogen that comes from the air. (Nitrogen is the main active ingredient in commercial lawn fertilizer). Rainwater, whether it comes as rainfall or from a rainwater storage tank, greens up your grass with free, natural fertilizer. And you will be "greener" since this free fertilizer isn't made from hydrocarbons.
Nationwide, we use about 150 gallons per day per person, which includes outdoor use. Indoors, we use about 70 gallons per day per person. Of that, less than 5% is used for drinking and cooking. Most is used for washing dishes and clothes, flushing toilets and bathing. It takes 2 gallons to brush your teeth, 2 to 7 gallons to flush a toilet, and 25 to 50 gallons to take a shower. If you have low-flow toilets and faucets, usage might drop to about 60 gallons per person. By using water-efficient appliances and water-conserving practices, you can achieve a daily per-person usage lower than 50 gallons per person.
There is really no such thing as a typical rainwater harvesting system - each system should be custom designed to fit the catchment area and the water end use. For aesthetic reasons, most systems are wet systems which means that the conveyance pipes from the downspouts to the tank are buried. Click here to view a variety of rainwater harvesting applications.
It depends. The biggest expense is the storage tank. You should strive to size your system appropriately so that you have just enough rainwater storage.
If you are building a brand-new house in the country, a rainwater harvesting system can cost less than drilling a well depending on depth of your groundwater, or slightly more than a well if you need a to store a lot of water.
If you are adding a rainwater harvesting system to an existing house, you need consider the following factors:
For typical systems with no unusual features or obstacles, a simple rule of thumb is that a 2,500 - 5,000 gallon system costs about $1.75 - $2.25 for every gallon of storage, excluding gutters. Systems 10,000 gallons and up cost between $1.00 and $1.75 for every gallon of storage, excluding gutters. Smaller systems are more expensive than larger systems due to fixed costs and economies of scale.
On-going maintenance costs depend primarily on the type of filtration and purification used and the number and type of pumps. The systems do require on-going maintenance and monitoring, but if you filter the rainwater before you store it, maintenance costs will be less.
The amount of storage you need depends on your use and the rainfall in your area. We use a "water budget" approach in planning your storage
needs. A water budget takes several factors into account, starting with an estimate of the monthly expected water demand calculated from your
planned use for the water. This is matched against the area's rainfall history and averages (historical amount and days between rainfalls). You
can think of storage as being like a bank account, with rain making the deposits, and water demand making the withdrawals each month. If you are
going to depend entirely on rainwater, the storage size you need would be that which has water in the "bank" all through a worst-case rainfall year.
Use the rainwater calculator to estimate how much storage you may need.
Tank capacity ranges anywhere from rain barrels of 60 gallons to huge steel tanks capable of holding more than 1 million gallons.
Most homeowners who want rainwater for landscaping use polyethylene or fiberglass tanks with a capacity of 5,000 - 10,000 gallons. Homeowners using the water for potable purposes use galvanized tanks ranging from 10,000 - 60,000 gallons. Commercial systems run the gamut from 2,500 gallons to 100,000 gallons depending on the catchment area and intended water end use. Commercial systems also use taller tanks than residential systems.
Typical tank sizes:
|1,500||Polyethylene||7' 3"||5' 5"|
|2,500||Polyethylene||7' 11"||7' 5"|
|5,000||Polyethylene||11' 9"||7' 2"|
|5,000||Galvanized Steel||12'||7' 3"|
|10,000||Galvanized Steel||14' 8"||7' 3"|
|10,000||Galvanized Steel||9'||21' 5"|
|15,000||Galvanized Steel||19' 6"||7' 3"|
|15,000||Galvanized Steel||12'||17' 11"|
|25,000||Galvanized Steel||24' 5"||7' 3"|
|25,000||Galvanized Steel||18'||14' 4"|
|35,000||Galvanized Steel||29' 3"||7' 3"|
|35,000||Galvanized Steel||24'||21' 5"|
Unfortunately, yes. Most homeowners tuck the tanks out of sight in a barn or shed or screen them with fencing or plantings. You can buy wood or steel tanks. While these tanks are more aesthetically appealing, they are usually more expensive than polyethylene or fiberglass tanks. No matter what material the tank is made of, the price per storage gallon goes down as the size goes up. Galvanized steel tanks in sizes above 10,000 gallons are often competitive with or less expensive per storage gallon than equivalent-sized polyethylene and fiberglass tanks.