I have submersible water pump. I take the water from a nearby brook. When it rains heavily, the water becomes full of sediment and the sediment clogs ther relief valve, which oafter a while fails to close completely and the water from the tanks is drained back to the brook. And then the pump is automatically turned on again.
Somebody suggested that I should install a "sediment filter". I inquired in the LOEW's hardware department and the did not know anything about it.
Can anybody suggest where to get a sediment filter and how to install it. My plumbing is a little complicated as I would have to instal any filter into a rubber hose that brings the water from the pump to the house.

By relief valve I think you mean a check valve. Where is the valve, just above the pump or near the tank?

Near the tank. It is difficult to get to it. I have to disassemble the stove to get to it, but I guess that it is the only way to replace the valve.

I think you would be better off installing a sand or sediment tank. That would just be another tank between the pump and the pressure tank. You pipe the water into the bottom half of the tank and out the top. The bigger the tank the better. This is just a place for the water to sit for a while so the sand or sediment can settle to the bottom. The should be a drain at the bottom so you can periodically flush the sediment out.

If you have enough sediment to clog the check valve any type of filter will clog just as fast.