Sunday, May 31, 2009

DIY lawn irrigation

Tired of lugging around 50 foot sections of garden hose every day to water the lawn, I set out to automate the system. I was told that water sprinklers were preferable to drip irrigation or soaker hoses. I went to Home Depot, Lowe's, Fred Meyer and Walmart to compare products and prices. When I put it all together later that same night, I ended up with an impressive system that makes watering the lawn a snap. And I found out that plumbing my lawn's irrigation is as much fun as aquarium plumbing; it is really satisfying when it all comes together well. My system basically consists of two separate runs of impact sprinklers. The lower run has three impact sprinklers and the upper run also has three impact sprinklers with a soaker hose added at the end. Each sprinkler is separated by 50 feet of garden hose.

The picture here shows what this looks like. The large rectangles are two voluminous water tanks that lead to pumps. One of the pumps has an expansion tank, while the other does not. These lead to a system of valves that may be opened or closed (indicated by "equal" signs) and water emitting devices (small circles). The water tank without an expansion tank is connected to the roof gutter via piping.

One of the more unique parts of the system is how the pump is operated. The pump sits above the underground rainwater storage tank, but in order to draw water up (since it is not submerged in the tank) it must first be primed with the addition of water to the pipe leading to it so that it can maintain a suction. I attached a garden hose to an outdoor water spigot on my house and put the other end on the garden tank pump. (You can see in the diagram that a system of valves links the two pumps together.) Water is forced into the garden tank pump when the nozzle is turned on. Once the garden tank pump and piping is filled, it is turned on and the outdoor water spigot is turned off. At this point the garden tank pump is fully operational. Due to the length of the irrigation lines only one run of sprinklers is operated at a time to maintain sufficient pressure in the system. It all works very smoothly and only the opening and closing of valves in the system is needed to start and stop the whole system from beginning to end. I can buy an automatic timer to run the system when I am on vacation, some of the fancier models of these use a moisture sensor to prevent over watering.

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