What to do if holding tank leaks into bilges or overflows

catmandoo

catmandoo

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Some time ago the vent on my holding tank came loose close to the tank with a slightly overfull full holding tank ( faulty alarm) and flooded my bilges . I was woken in the early hours by SWMBO saying " What is that horrible smell " Lifting up the floor boards I encountered a thick brown liquid swirling around under the cabin door .

With a bottom threaded plastic outlet ( not trying to be funny) on the plastic tank and a heavy hose attached I am increasingly aware of this other possible failure point . having experienced an overflow once its not really very funny

I know what I then did but wonder what others have done in the same situation .



Any comments and advice for a plan A or B
 
I can tell you what I did - got rid of the tank entirely! Now once the head has been flushed, the only poo on board is inside the guts of the crew, and they can mostly be relied upon to keep it there. No buckets of sewage swilling about, just a nice new seacock and a short length of top-quality hose.

(The old tank when we bought the boat was shot and needed removing anyway, so there was a decision to be made on whether to buy a new tank or just plumb straight through, gaining some much-needed locker space into the bargain. Had the tank been sound we probably would have left it there.)

Pete
 
Ditto, ditto. We've taken them off the last two boats because they were DIY installed and in our opinion not done well. We don't discharge poo off a beach and millions of fish and seals are pooing in the sea all the time.
 
catmandoo said:
I'd love to do tht but countries like Turkey insist on Holding tanks and I also don't like swimming round the boat in a nice bay in the Med to find a floating object close to my nose
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Absolutely - if I was in the Med, I would have a holding tank. It's morally non-optional in that part of the world, in my opinion. But I sail in the English Channel, where swimming around the boat is a fairly rare event!

Pete
 
prv said:
Absolutely - if I was in the Med, I would have a holding tank. It's morally non-optional in that part of the world, in my opinion. But I sail in the English Channel, where swimming around the boat is a fairly rare event!

Pete
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Quite, plus the loo macerates so it all comes out liquefied.
 
I am sure I read somewhere that it is more ecologically friendly to discharge small amounts of macerated poo than a tank full further offshore?
 
A chemical loo - Porta Potti - comes with it's own holding tank complete with carrying handle for taking to the disposal point or marina loos.

They are available in various sizes to suit headroom and have an empty / full guage.

No smells at all on modern units, unless so old the seals go hard; there are seal kits but the whole thing is cheap enough to replace.

Above all, no nasty holes in the hull.
 
Seajet said:
A chemical loo - Porta Potti - comes with it's own holding tank complete with carrying handle for taking to the disposal point or marina loos.

They are available in various sizes to suit headroom and have an empty / full guage.

No smells at all on modern units, unless so old the seals go hard; there are seal kits but the whole thing is cheap enough to replace.

Above all, no nasty holes in the hull.
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When we had a caravan 40 years ago we had a Porta Potti . I stil recall the chemical smell and the walks down to the loos with my carry case and having to dump its contents down the loo . In more remote locations - eg wild camping it was a dig a hole and bury so on a boat where marinas a few and far between then that involves a trip in the dinghy ashore with bucket and spade to bury the chemical contents in some secluded beauty spot under a tree or what ever . Don't even mention dumping at sea or putting in a plastic doggy bag and posting in the nearest refuse skip
 
catmandoo said:
With a bottom threaded plastic outlet ( not trying to be funny) on the plastic tank and a heavy hose attached I am increasingly aware of this other possible failure point .
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Think yourself lucky the contents of the holding tank was originally yours. I bought a boat with a full holding tank, bottom outlet and burned out pump. Borrowed industrial vacuum cleaner, bleach and a lot of time were the immediate answer. Replacing the tank has been on my "to do" list since then.

I was talking to another forumite about his holding tank recently. He has the discharge pipe connected at the top with a pipe down to the bottom of the tank. At first this seemed counter-intuitive (doesn't some get left in the bottom?) but pumps are pretty good at "sucking" and if you start at the top of the tank you probably have a better chance of a pipe run that just goes down. Certainly mitigates my fears of burnt out macerators. What are other peoples' thoughts on that?
 
laika said:
I was talking to another forumite about his holding tank recently. He has the discharge pipe connected at the top with a pipe down to the bottom of the tank. At first this seemed counter-intuitive (doesn't some get left in the bottom?) but pumps are pretty good at "sucking" and if you start at the top of the tank you probably have a better chance of a pipe run that just goes down. Certainly mitigates my fears of burnt out macerators. What are other peoples' thoughts on that?
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If I was going to pump out the tank, I think I'd definitely prefer a dip pipe from above. Less likely to have stuff settle in it and harden, and any leaks are far less catastrophic.

However, I think if there was space for it, I'd prefer a tall, narrow tank well above the waterline and emptied by gravity. No need for any pumps at all then (except the one on the toilet itself). The system is also simpler with no diverter valves - everything always goes through the tank, but if the outlet valve is open it falls straight through without stopping. The tank (with its air vent) acts as a very effective anti-siphon valve - water can't jump up the tank and into the inlet in the top of it. You do need a separate hold/release valve directly on the bottom of the tank, rather than just opening and closing the hull seacock. Otherwise solids (mostly shredded paper) settles into the pipe from tank to seacock and can block it. I would have an access hatch in the top of the tank directly above the exit, for rodding through if required.

Ideally, on a custom boat, I'd have the top of the tank almost hard up against the deckhead (just room for a pipe from the heads and its inlet elbow), a "fence" bonded on around the top of the tank, and the fence lightly sealed to the underneath of the deck and around the incoming hose. Then a deck plate above the tank access hatch, so that unblocking is something you do in the fresh air rather than squeezed into a locker and spilling noxious fluids into the bilge.

Pete
 
prv said:
However, I think if there was space for it, I'd prefer a tall, narrow tank well above the waterline and emptied by gravity.
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Agree for the reasons you say, but sadly space for that arrangement is not quite enough on my boat. Plus would involve enlarging the skin fitting as I believe 50mm is recommended for gravity feed.
 
laika said:
Agree for the reasons you say, but sadly space for that arrangement is not quite enough on my boat. Plus would involve enlarging the skin fitting as I believe 50mm is recommended for gravity feed.
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That is what I have on one of my boats, exiting through a standard Blakes, but with an isolating ball valve. Seems to work OK, but the tank is high up. On the other installation in another boat there is not enough vertical space because of other pipework to get an isolating valve in. However, if you only close the valve when you are in harbour and leave the tank empty when you can avoid blockages. A 50mm outlet is preferred, but again difficult to retrofit in most boats.
 
catmandoo said:
I know what I then did but wonder what others have done in the same situation?
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Jill and I have baled and dug our septic tank out twice, passing buckets out through a small manhole. It's not the most pleasant job on earth, but some people do it all day for a living. Just a matter of getting on with it. Posts on here from grown men advocating wearing Marigolds to change a joker valve always make me laugh.
 
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