my pump will draw water from the lake but won't hold pressure. The pressure tank will not fill with water.

Question

The tank is brand new and ran well for a month before the problem occured.

Is a check valve the same thing as a foot valve at the end of the pvc hose?

Also tonight I managed to prime the pump and get it going, however the pump was up to 40psi (and should of shut off) and now is running at 20 psi. I have no idea what the problem could be.

Answer 1

In order for any pumping system to hold pressure once the motor shuts off there must be a check valve in the line. Now you say that this system worked for a month before this problem occurred, so it seems like a logical possibility that since you're drawing water from a lake that there may be some foreign object, (twig, small fish, dirt, leaves, etc.), that could have been sucked up into the check valve and is holding it open, allowing the water that the pump just pulled up and pressurized into the tank to exit back into the lake as soon as the pump itself, shuts off. Worth a look.

Answer 2

I would suspect a leaking check valve. A check valve should open to allow water to come to the pressure tank from the lake, but close when the tank pressure reaches the set limit. A symptom would be that the pump cycles, even though no water is being used. The tank would fill, then slowly (or maybe speedily) drop to cause the pump to run again.