Holding tank size?

colind3782

colind3782

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At present we don't have a holding tank on our 1988 Furia 332, mainly because we have good marina facilities, there are only two of us on board and space is at a premium. The boat is nominally six berth and 33' long. Given the increasing regulation of heads and associated issues, I can see that I will have to fit a holding tank at some stage.

What would be a reasonable size for the tank given the above criteria?
 
My 34 has 2 heads each with a 40L tank both retro fitted. I'd say it's more a question of what space you have for it without overly compromising your living/storage space or access to machinery or equipment. If it's possible I'd strongly recommend a location which facilitates gravity discharge.
 
Irish Rover said:
My 34 has 2 heads each with a 40L tank both retro fitted. I'd say it's more a question of what space you have for it without overly compromising your living/storage space or access to machinery or equipment. If it's possible I'd strongly recommend a location which facilitates gravity discharge.
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That's the plan. It won't get used much so I'm wondering what the reasonable minimum size would be to satisfy the authorities and be usable when necessary.
 
colind3782 said:
That's the plan. It won't get used much so I'm wondering what the reasonable minimum size would be to satisfy the authorities and be usable when necessary.
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I'd say look at your available spaces and install as big a tank as you can without overly compromising anything else. You can buy ready tanks as small as around 15L but why go to the bother of plumbing for that if you have convenient space for a bigger tank.
 
Irish Rover said:
I'd say look at your available spaces and install as big a tank as you can without overly compromising anything else. You can buy ready tanks as small as around 15L but why go to the bother of plumbing for that if you have convenient space for a bigger tank.
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My thought as well having installed a gravity holding tank a couple of years ago.
 
In my searches on the subject I've not been able to find much more that this:

https://www.rya.org.uk/knowledge-advice/environmental-advice/Pages/waste-management.aspx

To quote 'Although no specific provisions are made for smaller pleasure vessels, it is important to consider the impact of discharging raw sewage from a sea toilet or holding tank into the sea.'

This surprises me a bit. We must be a responsible lot as, despite the loose rules (no punning now!), when anchoring in (eg) Newtown River I've never seen any evidence of a problem.

Does go on to some recommendations - 'If a holding tank is fitted it should be used and only emptied at either a pump out station or when more than 3 miles offshore' (if you don't have a tank you can do what you want? Doesn't this rule out the whole of the Solent?)

I'm keen to fit a holding tank. Until then relying on nearby pubs etc. (Speaking of Newtown, looks like the New Inn's back in business. Very upmarket looking web site!)

Cheers
 
colind3782 said:
That's the plan. It won't get used much so I'm wondering what the reasonable minimum size would be to satisfy the authorities and be usable when necessary.
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Don't think any laws (which are very limited anyway) specify a minimum size, although the RCD now requires new boats to be fitted with a tank which in smaller boats such as my 33 seem to be around 60l. Where laws relating to discharge are in place they are written to ban discharge in the locality, not forbid boats that don't have holding tanks. In the US they require a means of isolating the direct discharge in order to sail in restricted water such as the intracoastal but don't think this is so anywhere in Europe.

As already suggested fit the largest you can because the incremental cost of larger tanks is negligible out of the total cost. The constraint is almost always space but aim for a minimum of 40l. There is good guidance on designing and installing holding tanks on www.tek-tanks.com and www.leesan.com
 
Tranona said:
Don't think any laws (which are very limited anyway) specify a minimum size, although the RCD now requires new boats to be fitted with a tank which in smaller boats such as my 33 seem to be around 60l. Where laws relating to discharge are in place they are written to ban discharge in the locality, not forbid boats that don't have holding tanks. In the US they require a means of isolating the direct discharge in order to sail in restricted water such as the intracoastal but don't think this is so anywhere in Europe.

As already suggested fit the largest you can because the incremental cost of larger tanks is negligible out of the total cost. The constraint is almost always space but aim for a minimum of 40l. There is good guidance on designing and installing holding tanks on www.tek-tanks.com and www.leesan.com
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Tek Tanks and Leesan are both very helpful and knowledgeable imho.
 
Boathook said:
Tek Tanks and Leesan are both very helpful and knowledgeable imho.
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At SBS a man on the Lee San stand was most insistent that fitting a holding take without installing electric heads was a very bad idea. He said manual toilets pumps thru too much liquid. He wasn’t interested in discussing a holding tank set up with a manual set up. Tektank were much happier to discuss what I wanted.
 
I would guess 90 percent of holding tanks work from manual pumps - you just make sure you pump the minimum to clean and empty the bowl if you have a few friends on board and are staying a few nights at an anchorage or marina.
 
Tomaret said:
At SBS a man on the Lee San stand was most insistent that fitting a holding take without installing electric heads was a very bad idea. He said manual toilets pumps thru too much liquid. He wasn’t interested in discussing a holding tank set up with a manual set up. Tektank were much happier to discuss what I wanted.
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Salesman talk. While an electric toilet tends to use less water, the thing that controls the volume you pump is the length of the hose from the outlet from the toilet to the holding tank. you need to pump enough so the waste all goes in the tank and only clean water stays in the pipe. This is of course a bigger problem if the tank is remote from the toilet as in some installations. For example the factory installation on my last boat had the tank the opposite side of the boat with over 3m of pipe running through the bilges. I did not order that option but fitted a gravity tank immediately behind the toilet. My current boat has the same arrangement with short pipe runs.

Not surprised that Tek Tanks were more realistic - perhaps because they don't sell electric toilets, but suspect mainly because it is a load of B******s. There are literally 10s of thousands of boats fitted with manual toilets and holding tanks.

My choice, which I fitted to another boat, is a Lavac and a gravity tank (made by Tek Tanks). If you want it easy to add an electric pump. This is a much better set up than the new, cheap type electric macerator toilets.
 
Tranona said:
Salesman talk. While an electric toilet tends to use less water, the thing that controls the volume you pump is the length of the hose from the outlet from the toilet to the holding tank. you need to pump enough so the waste all goes in the tank and only clean water stays in the pipe.
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We take the exact opposite approach as we tried your method in our first year of ownership and found we were basically filling the holding tank with clean water more than waste. We see the long length of the outlet pipe as a useful part of the holding tank capacity and of course the gravity head as a bonus to keep the joker valves closed. All flushing when the seacock is shut must be just enough to clear the bowl into the outlet pipe and no more. Of course when seacock is open we can go back to the 12 pumps or more to clear the pipe.

Upside is obvious - the holding tank only contains waste water so probably triples its capacity compared to your method as four flushes will clear the bowl, not twelve to clear the pipe. Downsides are of course that the joker valve must be in tiptop shape so gets changed once or twice a year in each heads, and that eventually the outlet pipe starts leaking smells - so gets changed every 3-4 years.
 
Tomaret said:
At SBS a man on the Lee San stand was most insistent that fitting a holding take without installing electric heads was a very bad idea. He said manual toilets pumps thru too much liquid. He wasn’t interested in discussing a holding tank set up with a manual set up. Tektank were much happier to discuss what I wanted.
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We are in this situation. We have a Jabsco Lite electric toilet and 55 litre holding tank. The water throughput of the electric toilet is very small and as a consequence we suffer excessive joker valve and discharge pipework accumulations of salts. Small throughput is all very well when the holding tank is in use but of no value at all when the gravity tank is open. We try to flush the toilet twice when the tank is open, which has a negative effect on batteries.
 
Our 100 litre tank sits 1.5m to the side and higher than the toilet.

On short stays we flush 25+ times to keep the pipe clear. On longer stays the first user just clears the bowl and the second user pumps 20 times after clearing the bowl. Our longest stay at anchor has been 6 days when the tank was three quarters full at most.

If we intended to stay longer then we would maybe restrict pumping through a little more but that has not been the case so far. To cater for a full tank and a desire not to have a lengthy trip to empty the tank we carry a disposable toilet liner called Disposa-John. We bought 100 for around £40 (small quantities are much more expensive) but carrying these might overcome the OP’s concerns regarding legal requirements on tank capacity? They contain chrystaline chemicals to make them suitable for disposal to landfill (they say).

Our tank is gravity discharged via 2” pipe and seacock and has worked perfectly so far. In being careful with our flushing regime we hope to delay furring up constriction of pipe bore and delay the day that the pipes smell!
 
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Our holding tank set up is a little different. The tank is 125 litres. The tank is under the floor close to the heads. In tank mode, there is a fall from the toilet to the holding tank. The pipe is no more than a metre long. Little pumping required to ensure the pipe between tank and toilet stays clean. The holding tank has a manual pump out that works well enough.
 
Pavalijo said:
To cater for a full tank and a desire not to have a lengthy trip to empty the tank we carry a disposable toilet liner called Disposa-John. We bought 100 for around £40 (small quantities are much more expensive) but carrying these might overcome the OP’s concerns regarding legal requirements on tank capacity? They contain chrystaline chemicals to make them suitable for disposal to landfill (they say).
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Like many boat owners in Spain without a holding tank, we carry a small PortaPotti, brand new in it's box and stashed in the forecabin. Hasn't been tested but the rumour has it that it will suffice in the case of an inspection!
 
colind3782 said:
Like many boat owners in Spain without a holding tank, we carry a small PortaPotti, brand new in it's box and stashed in the forecabin. Hasn't been tested but the rumour has it that it will suffice in the case of an inspection!
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All it needs now is for someone to invent a collapsible PortaPotti to make a fortune.
 
We have a 135L Tek Tank on the forward and main loo and a separate smaller one on the aft cabin en suite. As inherited, all goes into the tanks until sucked out or pumped out. Just recently re-hosed the main one and added a diverter to allow direct discharge when required. We live in a marina behind closed lock gates, so need to be responsible users. Loos on board are used for solids only very rarely, like overnight or bad weather. Liquids to my mind could go directly overboard hence our optional diverter upgrade. We have tank gauges on both tanks and have never seen more than 'low' in our ownership. I put freshwater in regularly, via the shower hoses, and pump through and out at suitable opportunities to keep tanks 'sweet'. No paper, even ladies blotting bits goes, down the loos regardless but is put in small bins lined with scented and bio-degradable 'nappy' bags, tied and dumped in garbage usually daily We have electric diaphragm pumps on both tank's discharge outlets, but have had equally effective manual ones on two other boats

We spent time as liveaboards in the USA and they are truly 'anal' re holding tanks but unlike here at least have plentiful pump out places usually provided FOC if you buy fuel or are a berth holder ( we had a weekly pump out from the 'poop' boat in our home base). In the USA diverter and overboard seacocks are required to be locked off usually cable tied and to be caught by the poop police without same in place is an on the spot fine, even if valves were properly closed. We later had a boat with a tall vertical gravity drain tank installed in a wet locker, simple and effective, cable tied outlet natch. A berth neighbour got a $400 fine after a rough ride from the Bahamas, outlets were shut but not re-tied locked and mobile plod in the ICW joyfully made an arrest:disgust:.
 
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