Foot Valve

I get my water from the lake.It is always a chore in spring wading out in freezing cold water to ensure that the foot valve is in water deep enough to have the system work.

Is there a minimum depth that the FV has to be in order to pump water. I thought it had something to do with the local atmospheric pressure but a wise local told me this week that he does not think it matters what depth.

I would prefer to drop the assem bly off my dock where the FV would be around 15 inches below the surface.Will it work?

Any depth which assures you will never "suck air" e.g. from lake level dropping, waves/wakes/winds, etc. is what you want. Fifteen inches seems a bit shallow but it depends on how angry your lake can get I suppose.

"Not an expert, but a former lakeshore w/irrigation system owner."

That; and the total lift to the pump. 25 feet vertical is the maximum a pump can lift. From the top of water that is. Where the valve is in the water does not matter as far as the lift is concerned.

bob...

The inlet for a lake water supply should be in at least 4 feet of water; preferably deeper; and located between the surface and the bottom.

Most suspended solids (dirt of various kinds) either floats to the surface or sinks to the bottom. The water away from both is the cleanest.

Turbulence from wind and waves will stir the bottom and the top, so the farther you are from both, the better it is.

I usually use a float. A bleach bottle, bigger is better, works well for a seasonal float for a foot valve. It should be anchored, preferably with two anchors extending out from the float, so it won't be pulled in by the floating pipe or blown about by the wind.

With a float system you can haul it out with a boat.

I have done the same thing with submersible pumps, using a larger float.

If I read the comments correctly the distance the FV is below the surface does not matter , But one must consider wave action to determine the surface between wave peak and trough....CORRECT?

If the foot valve gets to shallow, it will whirlpool like a bathtub drain and suck air in. If you can’t get it deep enough to get bellow the wave action or the whirlpool effect, you can install a couple of square feet of a flat object above the foot valve. Plastic, metal, even plywood until it rots will work. Just cut a disk about 2' across and place the foot valve underneath it. The disk spreads out the surface area of the suction and allows it to work from a very shallow depth.