My situation: Underground cistern overflowing because of continuous breaking of inlet float valve.
I have an underground 1300 gallon plastic cistern that supplies all of our house water. Our cistern water comes from a shared well for which the two houses have their own plumbing coming of a tee. The separate plumbing is located in a well pump house for which our water supply is pushed by a pressure tank and managed by a 40 to 60 psi pressure switch. The black plastic piping to our cistern is 1" and runs more or less 200' from well pump house to our cistern. The cistern water inlet is controlled by a brass float valve. Our issue stems from the float rod eventually breaking because the valve will not fully close, for which allowing water to rise above the valve causing the rod with attached float to snap. Of course this leads to the cistern to overflow.
Because the deep depth of the well pump, we have methane in the water. The methane does travel with the water to the cistern. I am thinking this causes the valve not to fully seat. When the cistern is full of water and before the snapping of the float rod, I can hear escaping methane from the valve not closing all the way. This of course allows water leaking into the cistern allowing the catastrophe.
Now my question is, is water pressure to our cistern too high, or is the methane pressure causing the valve not to fully seat, or is it both? I am thinking of purchasing a more stout valve that can handle the high pressure. Possibly one of these: http://www.dultmeier.com/catalog/0.689.1011.5579
I appreciate any advice that can provided. Please let me know if you have questions and need more information. Thanks.
FYI, the cistern is vented and I pull the cover and allow the cistern to air out for an hour or so before I enter for repairs.