I have a swing check valve that is between the water meter and the main ball valve. I have a water pressure booster and noticed that when no faucet is open in the house the pressure drops slowly, making it hard to maintain water pressure. I've tested by turning on the pressure booster with 4 gallon pressure tank and closing the main ball valve. The water pressure held. As soon as I opened the main ball valve the pressure started to drop.
I opened the top nut on the swing check valve and tried cleaning with a tooth brush what I could. The valve does not seem to be corroded since it had been installed 2 years ago and moved pretty freely. After closing everything back up, it's the same. The pressure gradually starts lowering.
My utility water pressure is at 10 PSI and they won't do anything to increase it.
I wouldn't even know how to take it out since it is inside a circular irrigation box surrounded by concrete flooring.