[C320-list] Holding Tank Flooding

[Arthur Miller]

Had the exact same thing happen you have described.  The hull valve should be shut
When not using the macerator pump.  The pump has a rubber(?) impeller that can allow leakage back into the holding tank..
Art

Sent from my iPad

> On Jul 19, 2016, at 4:25 PM, Kaare Wold <sailor3952 at charter.net> wrote:
> 
> Skippers,  Recently we noticed that our holding tank fills with water when at rest at the dock.  At first, thought our dock attendants failed to pump out.  We have an AccuGage digital monitor on all tanks.  Love that setup! We had the tank pumped, while we were present,  and as the tank was being pumped out, I could see the AccuGage digital level drop from 3/4 to 1/2 down to empty. A couple days later, it was back to 3/4 full without any personal use whatsoever.  The macerator thruhull had been open all the time, although we never use that device.  All thruhull are opened for winter layup and I never closed it after spring launch.  I now closed the thruhull, had the tank pumped out again and.....bingo...,  the tank remained empty.  Any ideas from our knowledgeable group???   Could there be a check valve in the macerator pump that is leaking?    Looking for some suggestions or comments from someone that may have experienced the same problem.  Thanks to all for your comments.
> Kaare & Mary Wold
> Sheet Music, #945  Sturgeon Bay, WI