Installing Submersible Pump in Lake

We recently completed a job where we used a lake for our water source. The customer did not want a horizontal centrifugal pump mounted above ground for a couple of reasons. First he was concerned about the noise of the pump, and second was the cosmetic or looks of it. So, we came up with a solution of installing a submersible pump into the lake with a self-cleaning filter to keep algae and other debris from clogging up the pump and the system.

We used a 2 horse power 30 gallon per minute pump (gpm), with the zones designed and built at 24 gpm. This pump was plenty sufficient for the system which covers about 1/2 acre. The 2" pump was enclosed in a 4" schedule 40 PVC casing. The casing and pump was attached to a dock about 3' deep and 2'&1/2" off the bottom. The 4" casing was then supported with pipe straps and wire to secure it further.

Attached at the suction end was the self-cleaning filter. Out of the main-line was a 2" discharge with a 2"X 2" 1/2" slip X slip X thread tee with a 1/2 sch 40 line for the return line to the self-cleaning screen. This is what makes the screen spin ad keep debris off. After the 2" reducing tee with the return, a 2" check valve needs to be installed.

We reduced from 2" to 1&1&1/4" about 10' from the pump's discharge. We Ran 100' of 1&1/4" pipe down and about 20' out side the dock. We were then able to reduce to 1" and use 1" valves. Depending on the size of your system the size of pump needed may very and what size mainline you need to use can very.

Installing a submersible in a lake works great, but you must have it strapped or anchored properly so that it doesn't shift too much. A regular well screen gets clogged too quick in certain bodies of water and self-cleaning screens may take more time & money to install, but they definitely have their advantages.

Scott Young
http://www.autolawnsprinklers.com