Toilet, how to get the seawater out of the inlet pipe

[prv]

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Pete

 

[RichardS]

There's a weighted valve closing off the end of the inlet pipe. It's anaerobic bacteria in the seawater which cause the smell. I'm not concerned, as the inlet pipe on my boat is very short, and I don't notice any nasty smells, even when the boat's been unoccupied for a week or so.

The valve is not 100% effective but even if it was, the faecal matter is in the pump body on the inlet side above the piston as if finds its way past by lining the bore.

My boat was OK after a week or so in Med winter (read normal UK weather) but after a month or so the first pump always ponged.

It's not plain seawater but it's not important as if one gets the pong it can be easily sorted.

Richard

 

[EdWingfield]

There seems to be a theory here that some seas of ours are clean, where seabirds, mammals, fish and all the rest do not poo. Particularly it is in in the west of Scotland where there is believed to be no faecal matter in the water.

???

 

[RichardS]

There seems to be a theory here that some seas of ours are clean, where seabirds, mammals, fish and all the rest do not poo. Particularly it is in in the west of Scotland where there is believed to be no faecal matter in the water.

???

Completely different issues. Firstly there is the issue of concentration but, even more importantly, human faeces is alien to the marine environment as it's constituents are compounds derived from mostly from terrestrial environment. Seaborne animals, fish, birds etc are largely recycling what is already present. I would not be at all suprised if the degradation products from human faeces in seawater are fundamentally different from the degradation products of marine faeces.

Yuk! :ambivalence:

Richard

 

[EdWingfield]

Completely different issues. Firstly there is the issue of concentration but, even more importantly, human faeces is alien to the marine environment as it's constituents are compounds derived from mostly from terrestrial environment. Seaborne animals, fish, birds etc are largely recycling what is already present. I would not be at all suprised if the degradation products from human faeces in seawater are fundamentally different from the degradation products of marine faeces.

Yuk! :ambivalence:

Richard

Where are the higher and lower levels of concentration?
What do you mean by 'degradation products'.

 

[geem]

It's not the plankton. Try putting some seawater in a bottle and leave it lying about for a few days. It doesn't smell.

The smell is from effluent either being circulated back into the inlet pipe from the discharge underwater or leaking past the piston in the pump.

Not my expereience. If you have a watermaker in the tropics you know all about the effects of leaving salt water on the pre-filters for more than three days. You get a strong smell of rotten eggs. Its only seawater in there. The same thing happens with the loo. If you have pumped the loo twenty times the dilution effect is more than sufficient to ensure negligible effluent is recirculated. Fresh water in the loo cures the problem

 

[NormanS]

Not my expereience. If you have a watermaker in the tropics you know all about the effects of leaving salt water on the pre-filters for more than three days. You get a strong smell of rotten eggs. Its only seawater in there. The same thing happens with the loo. If you have pumped the loo twenty times the dilution effect is more than sufficient to ensure negligible effluent is recirculated. Fresh water in the loo cures the problem

That may well be an explanation. In our own case the loo outlet pipe is ridiculously long (6m), and so, following best practice, we give the pump at least 42 strokes. That is to avoid nasty build-up in the pipe. If it also coincidentally prevents bad smells, all well and good.

 

[RichardS]

Where are the higher and lower levels of concentration?
What do you mean by 'degradation products'.

I would have thought that the degradation products arising from bacterial action, one of which is hydrogen sulphide, was self-explanatory.

The concentration of marine faeces in seawater will be millions of times lower than the concentration of human faeces in the small volume of residual seawater in the toilet pump.

Richard

 

[Mistroma]

I think it may depend on the purity or otherwise of the seawater in which you sail. I have never experienced any nasty smells from the inlet water, no matter how long it's been left in the pipe. (West Coast of Scotland).

The inlet seacock is also on the opposite side from the outlet.

Probably more to do with location of seacocks. I modified my boat soon after purchase due to smell from forward head. No problem with aft head with holding tank. No problem with previous boat in same cruising area but different skin fitting locations.

Both boats were sailed on the West coast of Scotland.

 

[john_morris_uk]

Not my expereience. If you have a watermaker in the tropics you know all about the effects of leaving salt water on the pre-filters for more than three days. You get a strong smell of rotten eggs. Its only seawater in there. The same thing happens with the loo. If you have pumped the loo twenty times the dilution effect is more than sufficient to ensure negligible effluent is recirculated. Fresh water in the loo cures the problem

Odd as I have spent time in the tropics and never experienced that problem with a water maker. Two different boats with two types of water makers with associated filters.

 

[dje67]

Never had any smell problems with my Jabsco twist-and-lock. A wee trick, which might be a complete red-herring, is to pump through loads of times, then pump out the bowl, then do another couple of flush pumps. It leaves the pump full of water, rather than air. Worth a try - if it doesn't work, then I guess I've just been lucky!

 

[EdWingfield]

I would have thought that the degradation products arising from bacterial action, one of which is hydrogen sulphide, was self-explanatory.

The concentration of marine faeces in seawater will be millions of times lower than the concentration of human faeces in the small volume of residual seawater in the toilet pump.

Richard

Then Richard, we might expect sewage treatment plants to stink of hydrogen sulphide? But they don't.

I have been on my boat since end March. She'd been afloat all winter, mothballed, and with all seacocks closed. Upon arrival I opened seacocks to get bog working. Cor! But after that there has been no H2S. It's about dissolved O2 in the bog water. Our anaerobic bacteria friends produce H2S as a waste product, they cannot thrive where there is O2.

I suggest trying a regular change of bog water. ie. normal use.

 

[geem]

Odd as I have spent time in the tropics and never experienced that problem with a water maker. Two different boats with two types of water makers with associated filters.

We have also had two different boats with two different watermakers and it occured in both. On the current boat we have clear housings for the prefilters. If we leave seawater in them for more than a few days you can see the seawater deteriate and change colour. Open the filters up and you get bad egg smell. This is in pristine clear Caribbean waters. Our friends with watermakers all have the same issue. We all flush the watermakers regularly or use them to ensure we dont get the bad egg smell. Similar problem in the tropics if you have seawater in thr bilges. A friend couldnt work out why he had a permanent bad smell from the bilges. A leaky stern gland was dripping sea water into the bilge and just smelled. Rinsing with fresh water and pumping out solved the smell.

 

[Carmel2]

Disconnect the loo end of the pipe and pump out with one of these, then re fit in case you forget on your return.



Edit: Also useful for getting the last dregs out of the bottom of the bowel.

 

[RichardS]

Then Richard, we might expect sewage treatment plants to stink of hydrogen sulphide? But they don't.

I have been on my boat since end March. She'd been afloat all winter, mothballed, and with all seacocks closed. Upon arrival I opened seacocks to get bog working. Cor! But after that there has been no H2S. It's about dissolved O2 in the bog water. Our anaerobic bacteria friends produce H2S as a waste product, they cannot thrive where there is O2.

I suggest trying a regular change of bog water. ie. normal use.

I'm not sure why you keep quoting me Ed, as everything you say simply confirms my analysis although you still seem to be missing the main point.

Sewage plants don't stink of H2S because they ensure that O2 is always present during the bacteriological decomposition process, exactly as you describe in your post.

When you arrive at the boat the first pump or two stinks to high heaven, exactly as you suggest. However, if you regularly use the toilet then it doesn't smell because of the intake of fresh oxygenated seawater.

But have you actually read this thread? It's all about ensuring that those first few pumps after returning to the boat smell as fresh as the regular pumps after that ..... and I've given the 100% guaranteed, virtually zero cost, solution to that.

I'm beginning to wonder if you're just trying to pick an argument with me?

Richard

 

[Hydrozoan]

I’ve said it before, but I’ll try again.

Anaerobic sulfate-reducing bacteria use sulfate as an alternative source of oxygen, to oxidize organic food material in de-oxygenated water. Sea water contains high levels of sulfate.

So, to produce hydrogen sulfide organic matter is necessary for two reasons:

First, as food for the aerobic bacteria which, in a closed system, deplete the water of oxygen to the point at which the sulfate-reducing anaerobes can thrive.

Then, as food for the sulfate-reducing anaerobes which produce the hydrogen sulfide.

The organic material for both those steps need not be of faecal origin – it could in principle be natural organic material (e.g. the remains of dead plankton, humic and fulvic substances from land run-off etc.).

Some time ago, Vyv Cox did experiments storing ‘clean’ Aegean sea water in bottles and detected no hydrogen sulfide. However, I believe that the water might have been so naturally clean that it contained insufficient organic matter (or insufficient bacterial ‘seed’, or both) for these processes to occur to a detectable extent.

I did say I might repeat the experiment by incubating naturally organic-rich UK estuary water (e.g. during or immediately after the spring phytoplankton bloom) in sealed bottles in the dark but have not yet done so.

In summary, any organic matter susceptible to bacterial degradation – not just organic matter of faecal origin – can in principle be used by sulfate-reducing anaerobes to produce hydrogen sulfide. Those who say that faecal material specifically is essential to produce the rotten-eggs odour are IMO mistaken – though of course it can provide both the organic matter and the bacterial ‘seed’ and so may well be a cause of the smell in particular cases.

 

[EdWingfield]

Richard S, I must've misread/misunderstood something you wrote.

Apologies Matey

 

[john_morris_uk]

I’ve said it before, but I’ll try again.

Anaerobic sulfate-reducing bacteria use sulfate as an alternative source of oxygen, to oxidize organic food material in de-oxygenated water. Sea water contains high levels of sulfate.

So, to produce hydrogen sulfide organic matter is necessary for two reasons:

First, as food for the aerobic bacteria which, in a closed system, deplete the water of oxygen to the point at which the sulfate-reducing anaerobes can thrive.

Then, as food for the sulfate-reducing anaerobes which produce the hydrogen sulfide.

The organic material for both those steps need not be of faecal origin – it could in principle be natural organic material (e.g. the remains of dead plankton, humic and fulvic substances from land run-off etc.).

Some time ago, Vyv Cox did experiments storing ‘clean’ Aegean sea water in bottles and detected no hydrogen sulfide. However, I believe that the water might have been so naturally clean that it contained insufficient organic matter (or insufficient bacterial ‘seed’, or both) for these processes to occur to a detectable extent.

I did say I might repeat the experiment by incubating naturally organic-rich UK estuary water (e.g. during or immediately after the spring phytoplankton bloom) in sealed bottles in the dark but have not yet done so.

In summary, any organic matter susceptible to bacterial degradation – not just organic matter of faecal origin – can in principle be used by sulfate-reducing anaerobes to produce hydrogen sulfide. Those who say that faecal material specifically is essential to produce the rotten-eggs odour are IMO mistaken – though of course it can provide both the organic matter and the bacterial ‘seed’ and so may well be a cause of the smell in particular cases.

I remember the experiments and the discussions. Point taken regarding ANY source of organic matter.

I look forward to seeing the results of your experiments in due course.

 

[RichardS]

Those who say that faecal material specifically is essential to produce the rotten-eggs odour are IMO mistaken – though of course it can provide both the organic matter and the bacterial ‘seed’ and so may well be a cause of the smell in particular cases.

I can't say that I'm aware of anyone who has specifically said that. However, it is an inescapable fact that we are talking about toilets and therefore faecal matter will inevitably be present, unless the toilets have been installed for decorative purposes only.

Either way, the solution is the same.

Richard

 

[RichardS]

Richard S, I must've misread/misunderstood something you wrote.

Apologies Matey

No problem.

Richard