I had a funny
discovery yesterday that I thought I'd share. I have three fresh water tanks
on my boat: 90 gal in the bow under the v-berth, 40 gal low down amidships and 35 gal to starboard. There's a very nice manifold under the cabin sole
where all tanks' supply lines meet, each with a ball valve, and the line to the pump is fed. I've never completely trusted the electronic gauges, especially the one on the mid tank, and have just had an instinct something wasn't right.
Last week my wife and I left the dock
for a four day cruise
with just the 90 gal tank full and the other two near empty. When we returned the gauges said we used all 90 gal in big tank - which didn't seem at all plausible as we're pretty miserly with water
even on short cruises. Meanwhile the wacky gauge on the mid tank was showing about 75% full. These two facts were never so clear before. I opened the inspection
port on the mid tank and sure enough it had miraculously refilled itself!
To make a long story short (a fair amount of troubleshooting and bloody knuckles) the ball valve at the manifold for the mid tank had started to fail and was leaking ever so slowly when closed. Since the bow tank was full and is higher up, and the lower mid tank was empty, there was a suitable siphon effect for the bow tank to put pressure on the manifold and all the closed valves, and thus backfeed water into the mid tank. So, darn it, I don't have a miraculous never ending supply of fresh water, but I have solved
a mystery that's been lurking for a while. I think my gauges might actually be fine. I've changed the valve so now time will tell.
There's always something...