Flexible Holding Tanks

[BigART]

Has anyone any experience of flaxible holding tanks?

I have a reasonably big, barely used locker alongside the throne which would seem to be the ideal location, but would involve major surgery to get a rigid one in there. A couple of Qs
- What capacity would be required for a couple for 3-4 days for a couple?
- Do flexible tanks have a decent lifespan (3-4 years)?
- Can a standard bilge pump be used to empty it or is a specialist type needed?
- Any other issues I need to be aware of?

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by BigART on 19/10/2004 17:31 (server time).</FONT></P>

 

[HeadMistress]

Bladders are not a good choice for waste holding. They're invariably installed in an area of the boat that’s inaccessible to install a rigid tank—stuffed down any opening into a place big enough to contain it. And only rarely are the bladders properly secured to prevent any movement. Since sailboats are typically so much more “active” than houseboats or cruisers, heeling side to side, bladders move and chafe till they leak. Fittings must be owner-installed in some bladders, and because the tank is in an inaccessible place, it is almost impossible to install the fittings correctly. Rarely, if ever, is any holding tank checked or maintained, so it isn’t at all uncommon for a bladder to blow out its fittings at the first sign of a clog—even more common in bladders that aren’t vented (which should never be used for waste holding in any event, because waste produces expanding gasses that can blow out fittings or even burst the tank, and because.methane is flammable). And because bladders are designed to "hug" the contents, there's little or no air space, which makes it all but impossible to prevent very foul odors from belching out the vent each time the head is flushed. And finally, bladders have a very short life-span even under the best of conditions...only about 10-15 years (3-4 yrs isn't a decent lifespan for ANYthing!) , whereas a good quality rigid plastic tank will last as long as the boat itself. Cost is about the same.

So go with rigid plastic...your best source in the UK would be Tek-Tank...they can supply one to fit your space--which, btw, can be anywhere within about 6' of the toilet.

As for capacity needed...the average adult uses the toilet 5x/day...average flush is about a 1/2 gallon, which works out to about 2.5 gal/day/person. So two people continuously aboard would put about 5 gal/day into a tank...which means you'd need at least a 20 gal tank to last you 4 days...25 gal would be safer.

Yes, a standard manual diaphragm pump can be used to empty any tank.

<hr width=100% size=1>Peggie Hall
Specializing in marine sanitation since 1987

 

[BigART]

Thank you for that very thorough reply. I wish all boat kit manufacturers would take your view about the longevity of their products!

Now where is my circular saw......

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[bruce]

do not know about over there, but here in US there is a different standard for holding tanks and drinking water tanks, if it is like overhere, be sure to get the holding tank, better smell control etc. and use proper 'head' hoses, not the cheap hoses.

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[tsmyth]

One fellow I haerd of (in an 18 footer) foundn that he could buy some plastic bags (sturdy I presume) that he could clip to the loo. Periodically he unclipped the bag (rather carefully I presume) and emptied it somehwere.

Ray

<hr width=100% size=1>Heat Wave

 

[aroma]

hi
looked at a flexiable tank for water and the manufactor said the were only for temporary use only not for a permature fixture thats here in NZ, assume that applys for all flexy tank/bladders
Warren

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[BigART]

That does seem to be the general opinion. Oh, well. As I said, time for the circular saw....

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