Holding Tank/Pump out point on boat...

[Wes]

So we have got to the stage where we have installed our composting toilet. We have used them before in our van and we love it. Problem is we are not as mobile on a boat as we were in a van which we didn't account for so we need to figure out a solution for the urine part of the composting toilet. 

 

The urine receptacle has a capacity of 7l which lasts us about 2 or 3 days. There is no flushing so no extra water is added. This on a boat is not enough capacity so we are going to divert to a larger 70-100l (giving us about 20-30 days in between pump outs) tank but my question is doss this need to be a specific type of tank? 

 

We will locate the tank under the toilet for easy distribution of urine but what about the pump out part? Assuming a pipe running from vented tank to a skin pump out fitting? What about pressure when being pumped out and the tanks structural integrity?

 

Any info will be much appreciated...

[Chewbacka]

You need a black water tank.

whilst not the cheapest this is a good place browse for tanks, deck fittings and pipe/hose.

https://www.leesan.com/shop/tanks

If you don’t use sanitation grade hose, it will smell, but rigid waste pipe is better.  Depends upon your installation as to what is used.

When pumping out, the contents is sucked out, not blown, so the tank doesn’t go over pressure, but you must have some kind of vent to allow air in, otherwise the vacuum will collapse the tank.

[Wes]

Thanks for the response. Yeah I had a look at their products, a little expensive but it is what it is. 

 

So in essence we will have a tank with 3 holes. 

 

1) Urine entry

2) Suction point to get rid of waste

3) Vent which will sit next to the exit of #2 

 

Does the vent need to allow a specific amount of air through? So as to not collapse the tank? 

 

i.e will the vacuum from the pump out negate the vent if the vent is too small? 

[David Mack]

How are you going to get rid of the solid waste?

[mrsmelly]

Here we go again 😂

[Wes]

25 minutes ago, David Mack said:

How are you going to get rid of the solid waste?

 

The solids container lasts about a week. After that it's bagged and taken to a friend's plot to compost before being used as compost for non edible plants and garden. 

[Tracy D'arth]

And you will be dumping the urine where?

[David Mack]

If you fit a conventional pumpout tank for your urine you will be facing a cost of around £20 every time you pump out. Cheaper to store it in portable containers which you can empty at elsan points for free. 

[Tracy D'arth]

5 minutes ago, David Mack said:

If you fit a conventional pumpout tank for your urine you will be facing a cost of around £20 every time you pump out. Cheaper to store it in portable containers which you can empty at elsan points for free. 

If you are pumping out one you may as well pump out 2s too, same cost factor.

[merline]

13 minutes ago, Tracy D'arth said:

And you will be dumping the urine where?

Pump out holding tank, that's the point of this thread..

[mrsmelly]

6 minutes ago, David Mack said:

If you fit a conventional pumpout tank for your urine you will be facing a cost of around £20 every time you pump out. Cheaper to store it in portable containers which you can empty at elsan points for free. 

What, like a cassette toilet 😂............or a pump out system? you would think something had been invented by now 😄

[Stroudwater1]

Just now, Tracy D'arth said:

If you are pumping out one you may as well pump out 2s too, same cost factor.

Yes but then the friends plants won’t flourish so well 😉

[Wes]

23 minutes ago, Tracy D'arth said:

And you will be dumping the urine where?

 

Hey Tracy, it will be going into a holding tank which then gets pumped out. 

11 minutes ago, Stroudwater1 said:

Yes but then the friends plants won’t flourish so well 😉

 

Exactly. 

13 minutes ago, Tracy D'arth said:

If you are pumping out one you may as well pump out 2s too, same cost factor.

 

Well no because if we are shitting into tank we need chems to break it up. Composting toilet negates this and doesn't smell of those horrid chemicals. 

 

And as someone else already pointed, out my friend has to then purchase compost. 

[Tracy D'arth]

7 minutes ago, Wes said:

 

 

 

Well no because if we are shitting into tank we need chems to break it up. Composting toilet negates this and doesn't smell of those horrid chemicals. 

 

 

Untrue. Most pump out tanks work better with no chemicals at all. I have never had a smelly tank nor have I ever used chemicals. Faeces break up in a tank with water and urine present. A sea toilet also macerates as it is evacuated. I would not suggest a dump through however. 

[haggis]

9 minutes ago, Wes said:

 

 

Well no because if we are shitting into tank we need chems to break it up. Composting toilet negates this and doesn't smell of those horrid chemicals. 

. 

No, you don't need chemicals to break up your poo. The movement of the boat wil do it for you. Seems odd having a pump out system just for urine ! 

[Wes]

Every boat I've been on that had a tank with both solids and urine I've been able to smell. 

 

The composting toilet we have doesn't smell as the bacteria doesn't propagate due to solids being wet. 

 

Either way, it is what it is and we need a solution so that we have a bigger tank for the urine. 

2 minutes ago, haggis said:

No, you don't need chemicals to break up your poo. The movement of the boat wil do it for you. Seems odd having a pump out system just for urine ! 

 

As I explained in the original post having a 7 litre tank as the toilet is is not practical. In a van we could get to points to dispose of easily. Not so much on a boat so we need to pivot and figure out a solution that allows us to hold urine for longer periods which we can then pump out. 

[Iain_S]

As suggested above, why not use portable containers and empty for free at an Elsan point? The volume will be a LOT less than that of a normal pump out, but most pump outs are fixed price, independent of volume or time involved.

[Wes]

23 minutes ago, Iain_S said:

As suggested above, why not use portable containers and empty for free at an Elsan point? The volume will be a LOT less than that of a normal pump out, but most pump outs are fixed price, independent of volume or time involved.

 

Hey Ian,

 

Totally see the logic here but if we have a 100 liter tank it would mean we are only spending roughly £16-£20 a month to empty based on our average toilet use. 

 

Having bottles of urine about just ain't something I or the missus are keen on storing. 🤣

 

[ditchcrawler]

9 hours ago, Wes said:

So we have got to the stage where we have installed our composting toilet. We have used them before in our van and we love it. Problem is we are not as mobile on a boat as we were in a van which we didn't account for so we need to figure out a solution for the urine part of the composting toilet. 

 

The urine receptacle has a capacity of 7l which lasts us about 2 or 3 days.  

That's good going, I produce 2.5Lts per day, so I would produce 7Lt in 3 days myself, Its going to cost you £20 a time to get rid of  100Lts of wee. 

Edited September 6, 2022 by ditchcrawler

[Tracy D'arth]

8 minutes ago, ditchcrawler said:

That's good going, I produce 2.5Lts per day, so I would produce 7Lt in 3 days myself, Its going to cost you £20 a time to get rid of  100Lts of wee. 

£22 at an ABC marina. For that I can get 500 litres of sewage removed.

[jonathanA]

I think I would use a caravan black waste 20 L container that could be emptied at elsan points. That would give you over a weeks worth. 

[Alan de Enfield]

I think it must be a wind-up. No sane person would even consider it - the worst of all worlds.

 

It could only happen in London !!!

[Hudds Lad]

I love how you think a tank full of wazz isn’t going to smell, have you ever walked through an underpass or gone in a gents?  

Good luck with your project though, at least you’re trying to deal with it and not chuck it in the cut/hedgerow 👍

[Wes]

4 minutes ago, Hudds Lad said:

I love how you think a tank full of wazz isn’t going to smell, have you ever walked through an underpass or gone in a gents?  

Good luck with your project though, at least you’re trying to deal with it and not chuck it in the cut/hedgerow 👍

 

I'd rather be respectful of the countryside and everyone else using it. The main toilet chamber has a 12v fan which diverts all the smell outside and along with the smelly stone it has kept bad smells at bay. 

 

Unfortunately we didn't consider the time it takes to get to various elsans etc so need to pivot and figure out a solution  which I think isn't too much of an issue. 

[Onewheeler]

On 06/09/2022 at 12:07, Wes said:

So in essence we will have a tank with 3 holes. 

 

1) Urine entry

2) Suction point to get rid of waste

3) Vent which will sit next to the exit of #2

Ideally you will have two vent pipes from opposite ends of the tank and with their outlet points as far apart as possible to encourage air flow. Our old holding tank had 25 mm hoses with vents about 2 m apart and we never had any smells with no chemicals added. We now use a portapotti after the macerator toilet died. A much better solution.