Gtavity drained holding tanks proned to block?

[Robin]

I agree and the choice makes sense to us as the disadvantage seems to be a smell and a half filled bowl every other year, followed by a 15 minute joker valve change after clearing the pipe of any sewage at all.

Our USA loo guru added a non return valve to our gravity system when we replaced the loo, to prevent drain back even if the duckbill ( Joker) failed, a useful addition and helpful if inspecting or replacing the valve or the entire pump assembly ( we carried a spare Jabsco pump assembly) for quick swapover and rebuild at leisure later).

 

[MountainGoat]

I have a gravity fed tank and experience the back flow issue. It can be avoided by pumping dry until the pipe to the tank is completely full of air (it sounds different), then a couple of wet pumps to put a bit of water in the bowl.

We use the thin loo roll and I always make sure it's got plenty of water in the tank for a while to let the loo roll turn to mush before discharging it. It's not blocked yet, touch wood.

To simplify the back flow avoidance I am contemplating fitting a twist and lock pump to my Jabsco.

 

[Robin]

I have a gravity fed tank and experience the back flow issue. It can be avoided by pumping dry until the pipe to the tank is completely full of air (it sounds different), then a couple of wet pumps to put a bit of water in the bowl.

We use the thin loo roll and I always make sure it's got plenty of water in the tank for a while to let the loo roll turn to mush before discharging it. It's not blocked yet, touch wood.

To simplify the back flow avoidance I am contemplating fitting a twist and lock pump to my Jabsco.

our Jabsco was indeed a Twist'n Lock version and still improved by the addition of the non return valve. the holding tank feed went vertically for over 4ft before entering the top of the vertical tank.. Never needed to but the pumpout was right above and a rod could have been used to poke right down and through, at least as far as a 'Y' valve junction. Well thought out by Benny:encouragement:. We had 'free' weekly pumpouts in our home berth from the poop boat so never experienced a full tank situation.

 

[RichardS]

Our Heads specialist ( loo brain surgeon) told us only to use supermarket own brand eco -friendly type toilet paper as it dissolves in seconds and at all costs stay well away from super soft/comfy, multiple padded types. Worked perfectly for us at home or on two different boats ( one macerator pumped, one gravity system) AND it is cheaper. Just make sure you file finger nails well regularly. :ambivalence:

Any of the proper soft tissues will be fine. Just put a piece in a bottle with some water and give it a shake. Instant snow flakes.

Richard

 

[Ric]

When I installed my gravity holding tank two years ago, I read every single forum thread (ybw, cruisers forum, hisse-et-hoh) on the subject first.

Thus I installed a 1 1/2 inch through hull directly below the holding tank in a short vertical drop. I used good quality butyl rubber poo-hoses. I installed an additional non-return valve in the poo-tube, approx 30cm above the Jabsco joker valve so the joker valve has enough head to close, but not so much head that it back flows. I installed a carbon filter in the holding tank vent. I installed a magic-bullet dispenser in the flush inlet, above the waterline. I bought a big supply of water-soluble toilet paper.

So far, absolutely no blockages, no pongs, and no precipitation salt build up.