Holding tank information – may be of use

[Ollie Holden]

As part of Nutmeg’s recent refit, I had a holding tank fabricated by Tek-Tanks to a templated design (made out of cardboard!).   It fits under the starboard forwad V-berth.  Capacity is around 45 litres.  I spent a lot of time scratching my head to work out plumbing arrangements; it is not high enough to be gravity-fed.

The fitting on the left of the photo is the vent, which goes up to a vent fitting right up near the stem fitting in the bow.  I subsequently fitted a check valve to this pipe as I found that when fully heeled over in waves, the holding tank was backfilling from this vent.

I didn’t bother with a deck pump-out fitting – perhaps I’ll regret that one day but i couldn’t work out how to run the pipework and didn’t want another deck fitting on my nice new teak deck.

I only wanted a single pump, so I ended up with the below arrangement, which some (including my wife) would say is ugly and some (including me) would say is a plumbing work of art.  It looks less grubby now – the photo was taken during fitting.   It works really well, and the two valves mean I can pump from toilet or tank, and pump to sea or to tank.  There is a meter which you can see on the right of the photo, which is switched on with the light switch.

The observant amongst you will see that there are two vented inlet loops; one is for the seawater tap in the galley, which tee’s off the heads inlet.

I’m happy to provide further pictures or detail if it would help anyone.

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