Holding tank installation - any country standards to follow or do I get creative?

[Malabarista]

We fitted one last year. After reading Peggys book we went for the deck pumpout fitting directly above the seacock and got TecTanks to build us a tank that lined all the inlets/outlets up nicely. This enables us to rod through from above if needed. We also ran the 38mm tank vent for less than 1m which increases airflow over the poo ( i hope). This may be impossible in the OPs case but worth thinking about if anyone else is doing a complete install. BTW TecTanks are a great company to deal with and have much expertise to help with planning and fitting. Good luck with the install.
EDIT
Oops just got beaten to the draw ?

 

[Tranona]

GRAVITY it is: Thank you all - very much appreciated. I am actually currently looking into the pipe fittings and (since I already have an electric loo/macerator I shall go for gravity discharge.)

PUMP-OUT: So, a 38mm butyl pipe that runs from deck to bottom of tank (with the less possible bends) will be good for Marina pump-out?

For other readers that may be in the same... situation: here's the diagram of the tank I just purchased - it has a bottom pump-out fitting:
View attachment 109455

That is not suitable for a gravity tank. First decide on the system, second identify where the tank will fit, third buy the tank - or have it custom made if a standard tank does not fit.

The type of tank you need can be seen here

tek-tanks.com/product-category/tanks/series-a-tanks/series-a-vertical-waste-tanks/

Click on one of the tanks and you will find photos of a typical installation. On that site you will also find a wealth off information on designing your system. While the standard tanks are fine if you can fit one, a custom tank allows you to perhaps make better use of the space you have available and get the layout of the inlet and outlet to suit your specific installation. The downside is that typically they are twice the price of a standard type.

As I mentioned earlier Vetus have a similar range of standard gravity tanks which I know are available in Greece at similar prices to the Tek Tanks. You can also get tanks custom made in Greece using the same material and construction method as Tek Tanks. I had one made in Corfu. I have also had one custom made by Tek Tanks and the quality of each were comparable. What I found useful was discussing the problem with each maker as they have a fund of knowledge on tanks and installations. In both cases the end result was better than my original thoughts, in particular maximising the volume.

Good luck with your project.

With regard to the pumpout, it is normal to use an internal dip pipe which collects the waste from near the bottom of the tank. You can also have the tank designed for bottom entry using an internal stack pipe. This can be helpful to enable you to get the tank high enough to be above the waterline.

 

[Tranona]

Yes I found that when I searched after reading your post, it looked pretty thorough to me and covered every aspect of the system. It just struck me as funny that after you quoted the standard there was a post stating there was no standard. I would imagine Tranona was writing theirs when you posted so wouldn't have seen it

I guess what I was trying to say was that there are no requirements for retrofitting into an existing except the pumpout fitting. The ISO is for new builds and although I have not read it, I doubt there is anything in there that would add to or differ from the information provided by the sources of tanks etc.

 

[Norman_E]

If you can, keep it simple. Gravity, no pumps, no Ts, no Ys, fewest bends and a straight vertical line from pump out opening down to opening at the bottom of the tank for rodding. Make sure all pipes have easy access to change when smelly or full of limescale. Even this diagram doesn’t quite get it right as it lines up inlet from toilet to outlet instead of pump out opening to outlet.

Rupert W's post says it all. The only difference with my setup is that the tanks that were installed did not have an internal pipe for pump out. I solved that with a tee in the discharge pipe from the bottom of the tank to the sea cock, leading to a new deck fitting. My improvement is that I now flush the heads with fresh water, which almost eliminates the scaling of the pipework.

 

[jwfrary]

If you can, keep it simple. Gravity, no pumps, no Ts, no Ys, fewest bends and a straight vertical line from pump out opening down to opening at the bottom of the tank for rodding. Make sure all pipes have easy access to change when smelly or full of limescale. Even this diagram doesn’t quite get it right as it lines up inlet from toilet to outlet instead of pump out opening to outlet.

This would be the way I would do it. If you don't have the height to use a gravity emptying type system you can go though the top and use a Henderson Mk 5 to empty the tank via a skin fitting.
I use exhaust clamps on butyl hose with the reinforcing. The vetus carbon filters are very good

 

[Birdseye]

Hello all,

I just got miself a 50lt tank on special winter offer - which is to be installed in our 37' sailing boat.

Are there any standards that I need to follow - in relation to emptying said tank by shore services?
.

Couple of suggestions from personal experience of fitting one. Use abs welded pipe as much as possible - flexible toilet hose is micro porous and will eventually smell. Secondly dont allow paper into the holding tank pee and poo only. Used toilet paper into a pedal bin by the loo - it doesnt smell.

Rather than get involved in pumping out the tank I thought I would use a diaphragm pump to prime a syphon. We got ourselves stuck in a spanish yacht club marina where the toilets were a long way away so we used the on board and filled up the holding tank ( 50 litres is small) quickly. It being a foul night and dark, not sensible to put to sea, I thought I would empty the tank in the marina which was open to the sea and we were the first berth in - so it would quickly wash away I thought. . Stuck my head out and was apalled to see a huge brown stain on the water spreading through all the boats and no way of stopping it.

Dont be tempted.

 

[Tranona]

Use abs welded pipe as much as possible - flexible toilet hose is micro porous and will eventually smell.

That is not true of butyl sanitary hose, which is why it is recommended rather than the older PVC coated hose which is porous.

 

[Robin]

Couple of suggestions from personal experience of fitting one. Use abs welded pipe as much as possible - flexible toilet hose is micro porous and will eventually smell. Secondly dont allow paper into the holding tank pee and poo only. Used toilet paper into a pedal bin by the loo - it doesnt smell.

Rather than get involved in pumping out the tank I thought I would use a diaphragm pump to prime a syphon. We got ourselves stuck in a spanish yacht club marina where the toilets were a long way away so we used the on board and filled up the holding tank ( 50 litres is small) quickly. It being a foul night and dark, not sensible to put to sea, I thought I would empty the tank in the marina which was open to the sea and we were the first berth in - so it would quickly wash away I thought. . Stuck my head out and was apalled to see a huge brown stain on the water spreading through all the boats and no way of stopping it.

Dont be tempted.

We put a 'nappy sack' in thre bin as a liner, cheapo ones but are scented regardless. From our live aboard time in the USA where they are truly 'anal' about holding tanks and discharges we learned only ever to use the cheapest supermarket brand 'eco' paper as it break sdown rapidly but just make sure to keep your nails filed short and smooth .

 

[ip485]

Secondly dont allow paper into the holding tank pee and poo only.

Why? Are you concerned about blockage or pollution, or something else?

I have to say, never had a problem with my fresh water Vac. Flush loos.

BTW I have heard a tale on a charter yacht of a guest who followed all the rules about nothing in the loo unless you have eaten or drunk it, except they took to eating the olive stones. Caused no end of problems and they werent flavour of the season!

 

[RupertW]

Why? Are you concerned about blockage or pollution, or something else?

I have to say, never had a problem with my fresh water Vac. Flush loos.

BTW I have heard a tale on a charter yacht of a guest who followed all the rules about nothing in the loo unless you have eaten or drunk it, except they took to eating the olive stones. Caused no end of problems and they werent flavour of the season!

We also follow the “No paper rule” - partly pollution, partly to avoid blockages particularly as the holding tanks are used almost all the time and it could be a week before they get emptied. Another very occasional accidental advantage is that when somebody accidentally releases the contents into an anchorage the sea life rapidly deals with it, whereas I find it ghastly when I see paper floating around and settling when snorkelling in an turquoise bay.

 

[pvb]

The "no paper rule" is surely the only civilised way to operate a holding tank which is likely to get discharged to sea?

 

[Bilgediver]

Deck Pump Out Part Nos (Leesan / Tek Tanks ) 276801 /02989 is what I used. I think a standard size. I fitted a 50l tank and made it gravity emptying. The pump out was a dip pipe straight to the tank. I put in a flush out fitting too directly above the outlet so I could rod it out from above in the event of a blockage. I put the tank in the cupboard behind and just above the loo. Minimum number and lengths of pipe and only one valve (excluding the seacocks). Everything goes through the tank so if the valve is closed it fills up. If the valve is open is goes straight in and out again.

The pump out connection is a standard size bore as per the Tek Tanks details in another post as the Taper nozzle at the pump out station has to enter and then seal so as to enable no air leakage and so maintain the vacuum in the outlet. Non standard pump out connections might not be appreciated.

 

[antaris]

Thank you all - there is a wealth of info here.

I shall get to the drawing board and return with plans! I surely must get this right... no space for error...