SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

If you are using lake water and you are not injecting fertilizer, I would say you may not need a backflow prevention device. You should check with the community personnel responsible for the lake to see what rules they have set. You just do not want to contaminate the water if people swim or fish there. However, like I said if you are just using the water for the sprinkler system and you are not injecting fertilizer, you can probably go without the backflow device.

You should read the following link with respect to using lake water and possible problems if you do not use the right valves:
http://www.sprinklerwarehouse.com/shop3/valves_info_for_dirtywater.htm

Also consider using a foot valve to keep the suction line to the pump full of water, and use a burrel with holes or a vault to keep the dirt and plant life out of the suction line, You may also consider filtering the water using a filter found on the following link:
http://www.sprinklerwarehouse.com/shop3/MiscMisc.html
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I don't know what to say on this one. What would be the difference between injecting fertilizer concentrate into the sprinkler system only to have a small amount backflow into the lake and only irrigating with lake water but drop spreading granular fertilizer which will leech into the lake anyway with the irrigation water you spray on it?

go wit sprinklerwarehouse irrigatior on that one!

Thanks
Ray
Rays Above and Beyond Automatic Lawn Sprinklers