How to clear the holding tank's exit pipe/ sea cock

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What do you do with the shitty bog paper?:ambivalence:

Bag it, this is common on land too in the Greek islands. There'll be a bin next to the loo for the purpose.

 

[jordanbasset]

What do you do with the shitty bog paper?:ambivalence:

we've never had a problem flushing it away over the last 15 years or so.

Bag it, this is common on land too in the Greek islands. There'll be a bin next to the loo for the purpose.

Yes, exactly what we do. Use nappy type bags which we seal and then put in a bin (with a bin liner) which is next to the toilet.

 

[BabaYaga]

I understand from a friend who has dismantled and cleared quite a few that the usual cause is a build up of limescale or similar deposits slowing reducing the diameter of the exit pipe at the bottom of the tank. Regular rodding and dilute acid treatment are recommended. Ours can be rodded from the discharge fitting on the side deck.

Scale build up could certainly be an issue, but perhaps less likely if it is indeed normal practice to leave the seacock under a through-flow tank open at all times? Anyway, sanitation hoses need to be removed for clearing/replacement every five, six years or so in my view.

Regarding the 'wrong paper theory', I find it hard to understand why matter that has happily passed through the toilet and the pipework should reform into solids causing blockages just because it is kept in the holding tank – unless there is insufficient fluid present.

Cannot help thinking that a system that relies on regular rodding or use of chemicals is badly designed. (Sorry, not much help to the OP, I know...)

 

[Daydream believer]

Just had the problem 2 weeks ago whilst on hols in Holland. The pipe below the tank blocked & the holding tank filled up. Normally i have the vent pipe taped up so that any soil pumped into the tank is forced straight out the bottom as pressure in the tank builds. But if the vent is open then a slight blockage can build up & the air can escape out the vent & the paper etc can collect at the bottom causing the blockage.
We pumped as hard as possible & the result was that the joker valve reversed.
I removed the deck plug & was sprayed with soil & just managed to catch the bung ( plus a hand full of shit) before it blew over the side. We went to a pumping station to remove some of the contents of the holding tank
We removed the bottom pipe using the shore side pump to catch some of the water as it leaked from the pipe as we released the joints. We were sprayed with muck as we had to crouch in the locker whilst doing this. I also have a detachable pipe that connects to the shower pump using a hose lock fitting for hoovering up any water from under the engine. Unfortunately I tried to use this & it clogged solid & this morning I had to strip the shower pump at home & the stink was horrendous. Fortunately the wife was still in bed as I did it very early in the butler sink in the utility room but she did query the whiff afterwards !!!! I blamed next door's dog.
In spite of attempts to clear it up I still collected 2 buckets full from the bilges yesterday when I lifted the floorboards several days after the main event.
The fact is that one has to put on old clothes , bite the bullet & get on with it.
Then go & have a shower ( I am having mine next week!!)& dump the old clothes in the wash or the bin

 

[Thistle]

I don't have experience of a holding tank but do wonder if part of the problem is not emptying it and flushing it through thoroughly on a regular basis so that neither scale nor compacted masses of [whatever has been put down the heads] has a chance to build up?

 

[vyv_cox]

I don't have experience of a holding tank but do wonder if part of the problem is not emptying it and flushing it through thoroughly on a regular basis so that neither scale nor compacted masses of [whatever has been put down the heads] has a chance to build up?

Our holding tank is installed as a gravity type, with the outlet hose between tank and seacock very short, about six inches. The boat is in permanent use for six months of the year. The seacock is normally open except when we do not wish to discharge the contents, i.e. in anchorages and harbours. The height of the tank relative to sea level ensures that it is partially flushed during beating to windward.

Over the season some scale develops inside the tank and discharge hose. Unlike the relatively soft carbonates that develop between the toilet and tank/seacock (if a tank is not fitted) the scale in the tank is hard and compact. It would take a great deal of hydrochloric acid or a tanker full of vinegar to shift it. At the end of the season I flush through with water, open the inspection hatch and use a combination of banging on the outside, scraping with a stick and water jetting to remove it. Care is needed as some of the scale easily lodges in the outlet hose and it must be ensured that this is cleared.

The hose between toilet and tank does benefit from regular applications of HCl but every couple of years the scale right at the top of the loop needs to be cleared physically by removing the hose and either banging it agains a wall or replacing the hose.

 

[johnalison]

We had not noticed any change in the operation of the loo or holding tank after 16 seasons, but the holding tank valve was getting stiff and this spring I was given an ultimatum to get it fixed or there would be no cruise. With little time to go, I got our engineer to take it apart, and the valve lever had completely corroded, which was not surprising, but the rest of the outlet pipe had built up scale and the bore was less than half the pipe's diameter. This did surprise me as we always made sure that everything was well pumped through after use. The pipes were replaced and the T-piece and discharge valve cleaned with brick cleaner. It looks as if some build-up is unavoidable, and regular de scaling worthwhile.

 

[RupertW]

Bag it, this is common on land too in the Greek islands. There'll be a bin next to the loo for the purpose.

Exactly - just what they would do ashore at a bar, cafe or hotel - a small lined pedal bin, frequently emptied. We have had no blockages at all in 6 seasons with many many guests most of whom are new to sailing.

 

[SeamanStaines]

From many years of 'fecal matter' exposions and copius unblocking there is only really one solution. Every two years, even though its working properly replace the pipes whilst they are still reasonable clean. The with the pipe removed open the seacock for a minute or so. Waiting just compounds the problem! The cost of new pipework is nothing compared with the alternative.

 

[RupertW]

From many years of 'fecal matter' exposions and copius unblocking there is only really one solution. Every two years, even though its working properly replace the pipes whilst they are still reasonable clean. The with the pipe removed open the seacock for a minute or so. Waiting just compounds the problem! The cost of new pipework is nothing compared with the alternative.

As a matter of interest as you have had to unblock many times did people put paper down the loo?

Agree that replacing pipes (about every 5 years in our case) is the right thing to do as the build up scale is significant. What worries me is the 17 year old holding tanks which we can't get into easily. Changing them won't be much fun.

 

[derekgillard]

Yes, exactly what we do. Use nappy type bags which we seal and then put in a bin (with a bin liner) which is next to the toilet.

+ 1 have not had an issue since the rule was introduced

 

[Gilesferr]

From experience rodding with a straightened coat hanger from a dinghy may work although It may just push the blockage back into the tank,

Blocking the breather and pumping the toilet to build up some pressure is a good place to start but watch out or you might invert the joker valve in the toilet, or if you holding tank is a bit on the thin side, spit it but I'd think that pritty unlikely.

If that fails bin bag on hand close seacock and take pipe off seacock black bag to catch the residue.

If you get your crew involved it probably won't happen again.

 

[NPMR]

Our solution to the problem was to acquire/buy a long length of reinforced hose pipe and poke it into the deck fitting for emptying the tank.

By persistent and vigorous twisting, turning and vertical movements, we were able to stir the whole sorry mess until there was a 'whoosh' and the contents emptied downwards into the sea. We then squirted a hose pipe into the tank and flushed it thoroughly. (We have a dedicated holding tank kit now, which includes the hose pipe and a dedicated hose end to shove in the tank for flushing so as not to contaminate and supply hose).

The cure to mostly stop it happening is to only allow minimal paper use. Baby wipes are used instead which a) work nicely and b) 'wrap' up any smell etc. These are tidied away in the main rubbish, after further wrapping in a clean baby wipe - making them not dissimilar, perhaps to a baby's throwaway nappy.

Regular flushing is important. And, I've fitted a monitor to tell me its full, before it starts discharging over the side through the breather hole. This winter I'm contemplating putting in 'Y' valve and bypassing the holding tank, for use when not in a marina - reasonably often.

 

[Joker]

Pump out using the shore suction pump BUT leave the seacock open.

 

[BelleSerene]

Pump out using the shore suction pump BUT leave the seacock open.

That's clever - the idea being that it'll empty the tank and then start sucking sea water up complete with the offending blockage?

 

[RichardS]

That's clever - the idea being that it'll empty the tank and then start sucking sea water up complete with the offending blockage?

Probably not. I would have thought that once the tank is empty and the level has dropped to the bottom of the suction tube then the pump would simply start sucking air in through the tank vent.

Richard

 

[SeamanStaines]

The issue I have had is that calcium builds up in the pipe. Varying salinity combined with disinfectants breaks this up and it dislodges in lumps. Sooner or later a couple of these go down at the same time and jam, which then collects anything else that goes down. No amount of acid will remove it because the pipes are below the water line so the acid is very diluted with salt water by the time it gets there. Thats why I say just replace the pipes to get rid of the build up. My view is thatits such a disgusting job to get the pipes out I would much rather simply throw them away and replace rather than clean them! It is not helped by the fact that in our design the through hull has an elbow on it, to change the direction just before the seacock.

 

[Daydream believer]

Probably not. I would have thought that once the tank is empty and the level has dropped to the bottom of the suction tube then the pump would simply start sucking air in through the tank vent.

Richard

Which is exactly what happened to us, so we blocked that & it then sucked air via the heads, & as the suction on some shore side pumps is low nothing else happened other than a very small amount of air being drawn in round the inlet hose

 

[ItchenSailor]

Probably not. I would have thought that once the tank is empty and the level has dropped to the bottom of the suction tube then the pump would simply start sucking air in through the tank vent.

Richard

We've had to do this a couple of times. We have a handy crew member with a rubber glove covering the vent. We allow the suction to build up in the shoreside pump out , open the valve and whoosh. We allow the sea water to flow through so we know its clear.
Saves an awful lot of unpleasantness...

 

[KevB]

mole grips on the pipe just where it enters the skin fitting

Have hose pipe ready and with nozzle.

With stop cock closed remove pipe and stick hose nozzle in it. remove mole grips, turn on nozzle and let it back flush for a few seconds. refit mole grips. Reconnect waste pipe, open stop cock, remove mole grips and empty. hopefully....