Just a heads up to other Catalina 310 owners about a possible problem with a check valve located in the water line prior to the fresh water entering the hot water heater. On our C310 this valve had no ribs to help hold the hose and separated one night around 2am (we were asleep on the boat, and had neglected to turn off the water pressure.) The water pump woke us up, followed by the bilge pump turning on as the pump tried to empty our entire holding tank into the back of the boat. When I finally woke up and realised what was happening I turned the water pressure off and then later inspected this check valve and was astonished at what I found. This one-way valve was a very cheap plastic valve that had no place in a presurized system and certainly had no place on a boat. It was spliced into the water line about 6 inches from the hot water heater, and was bound to fail, as it had no way to grip the water line that was clamped to each end. When I removed it, I found that one side had already colapsed from the hose clamp. I replaced it with a brass one-way valve from the hardware store for about $5. If you own a C310 or C320 with the Seaward Hot water tank, I would take a look at your setup to insure that you do not have this problem component.