Installation of a Rainwater Harvesting System for household use on a house being built is easier than one already built. With knowledge of components needed and planning, it is not difficult to install in either case. If you have any plumbing skills, it can be a do-it-yourself with a bit of help.
Installation for home use goes like this; the roof is connected to the rain gutter, the rain gutter is connected to the downspout, the downspout is connected to the 4" or 6" PVC collection pipe, the collection pipe is connected to the storage tank with first flush pipe extension along the way, the tank has two outlet connections an overflow and an outlet pipe connected to the pump, the pump is connected to the pressure tank, the pressure tank is connected to the particulate filter or filters, the particulate filter is connected to the UV filter and the UV filter is connected to the plumbed house pipe. And the water runs all around!
Installation of Rainwater Harvesting on a house or building for yard and garden does not have so many pieces. It is the same as the above description but only to the storage tank, whatever type that might be. The stored rainwater does not go to a pump unless gravity feed cannot be used; then it may need to be connected to a pump and pressure tank, but no filters are usually needed.
In some cases where roofs have overhanging trees, additional screening for trash (leaves, sticks, nuts etc.) may be needed. There are several ways to do that, based on need and volume of trash. The maintenance for any system requires the dumping of the first flush and cleaning any screens and changing filters. Some are done monthly, some after each rain, and the UV filter lamp gets replaced once a year.
Now what are all these parts for? I’m assuming that no explanation is needed for the familiar parts - roof, gutter, downspout, pipes and their connections, pump, pressure tank and storage tank? That leaves first flush and filters.
First flush was originally called roof washer, a term used to describe the removal of leaves, sticks, nuts, etc., flowing with the rainwater off the roof prior to reaching the storage tanks. The commercial roof washer, a plastic box approximately 2’x 3’x 3,’ is installed in line with the 4" collection pipe and before the water goes into the storage tanks.
However, the most efficient first flush was dubbed “the poor man’s roof washer,” because it is cheaper to install and maintain. This too is in line with the 4" pipe but it is 4" pipe. A “Y” connection is installed with the vertical drop a minimum of 10’ and a threaded plug end to catch the trash. Once this fills up, the water flowing into the tank will have a minimum of sediment. After a rain, the plug is removed to allow the dirty water to flush out the pipe and replacing the plug makes it ready for the next rain. Note: The amount of water you lose depends on the length and size of pipe. Figure approximately 1 gallon of water for each foot of 4" pipe and 1 1/2 gallons per foot if you are using 6" pipe.
Drainage area for both overflow and first flush pipe needs to be a minimum of 10 feet from building foundation, an area where the runoff can be used if possible or cause no damage. There is no reason why it cannot go into a raingarden or another holding tank for garden use. The idea is to harvest as much as possible and make it work for you.
The number of filters may be a personal choice. You will need at least one particulate filter and maybe a carbon particulate filter too. If you use copper pipe in the house you may want an oyster shell filter as rainwater can be acidic, which can dissolve copper pipe. The choices are limitless. The UV filter is a must if you are using the rainwater for human consumption. The UV light filter kills the bacteria that can be washed off the roof.
PVC pipe gives you the ease of assembly and comes in sizes readily available. The application will determine the size. The number of linear feet of pipe necessary will depend on the distance from roof downspout to tanks and tanks to pump/filter system. The storage tanks will have punch-outs for pipe attachment; check the sizes.
These are the basic components to a Rainwater Harvesting System. Before you begin putting in a system, do some homework to locate resources and components and get the prices that best suit your situation. Help the environment and yourself by installing a Rainwater Harvesting System for your home and property.
A Rainwater Harvesting Workshop will be held at Meadows of Flat Creek Lavender Farm and Ranch at Noon on October 3rd at 852 Flat Creek Road, Johnson City during the 2nd Annual Texas Hill Country Lavender Festival. For more information about the workshop and Rainwater Harvesting call the Blanco County AgriLife extension office at 830-868-7167. We will be glad to help.