Flushing with fresh water

[PCUK]

All my previous systems have been sea water flush but this time I want to use fresh water from the tank. The toilet is a Jabsco Liteflush and the instructions say not to flush via a pressurised water system which is understandable. If I connect the flush between the tank and the pump via a non return valve so it is before the pressurised side and the toilet pump draws the water from the tank in the same way as it would from the sea, is that more or less the normal method for fresh water flushing?

 

[NormanS]

Personally, there is no way that I would have a toilet flushing pump connected to my freshwater drinking tank. Yeuch!

 

[nigelmercier]

All my previous systems have been sea water flush but this time I want to use fresh water from the tank...

May I ask why?

 

[Pinnacle]

May I ask why?

To avoid the pong when you flush for the first time after a week away from the boat??

 

[sailorman]

To avoid the pong when you flush for the first time after a week away from the boat??

That emanates from dead sea life in the inlet pipe

 

[vyv_cox]

Fresh water flush toilets use a dedicated tank that has no connection to any other domestic supply. Non-return valves never work 100% and many cheap marine ones are particularly poor, relying on a rubber flap valve. The reason that marine toilets smell when flushed after a week's resting is exactly that - faeces passes the rubber flap non-return valve into the suction side, contaminates the water in the suction pipe and bacterial action does the rest.

 

[JumbleDuck]

Personally, there is no way that I would have a toilet flushing pump connected to my freshwater drinking tank. Yeuch!

I agree completely. In most toilets (the Jabsco / RM69/ ITT types) the flushing and waste water are pumped by opposite sides of the same piston, with an O-ring seal. If they is a blockage of any sort on the waste water outlet side, the increased pressure there can cause waste to blowback past the O-ring and into the flushing side. Even a little raw sewage in the drinking water supply could spoil your month.

 

[PCUK]

The Liteflush uses separate electric pumps so there is no possibility of contamination and all the fresh water systems I have come across use water from the main tank. The only reason for the non return valve is to stop the toilet trying to draw water back through the domestic pump plus another to stop the domestic pump trying to do the same.
By the way Nigel, it's as previously said, to prevent smells and also to remove another sea-cock from the hull.

>>>>
The reason that marine toilets smell when flushed after a week's resting is exactly that - faeces passes the rubber flap non-return valve into the suction side, contaminates the water in the suction pipe and bacterial action does the rest.
>>>>
No, it's the stale seawater which is why it smells of rotten eggs and not sh*t.

 

[nigelmercier]

That emanates from dead sea life in the inlet pipe

Quite, and easily fixed with a Milton tablet in the inlet filter on first use.

 

[PCUK]

Inlet filter?

 

[FulmarJeddo]

The Liteflush uses separate electric pumps so there is no possibility of contamination and all the fresh water systems I have come across use water from the main tank. The only reason for the non return valve is to stop the toilet trying to draw water back through the domestic pump plus another to stop the domestic pump trying to do the same.
By the way Nigel, it's as previously said, to prevent smells and also to remove another sea-cock from the hull.

>>>>
The reason that marine toilets smell when flushed after a week's resting is exactly that - faeces passes the rubber flap non-return valve into the suction side, contaminates the water in the suction pipe and bacterial action does the rest.
>>>>
No, it's the stale seawater which is why it smells of rotten eggs and not sh*t.

I think you will find Vyv was correct. My last boat always smelt of rotten eggs after the first flush. I changed boats and found there was no smell after the first flush for the first season. 2nd year the smell started and the pump became stiff to operate. I stripped the pump down, cleaned it and greased the seals with silicone grease (from the plumbers shop) and no smell again. That reminds me of another job to add to the list before launch.

 

[duncan99210]

The smell is due to bacteria in the sea water having time to feed in the pipework. Part of their metabolism produces hydrogen sulphide which gives you the bad eggs smell on first using the sea water flush. There are a variety of systems available to fit between the inlet and the pump which put a bug killer into the water, reducing or stopping the smell. We've just fitted one by Jabsco to the aft head which seems to do the business; there was one by Leesan already fitted to the forward head which also seems to work quire well. The bacteria is present is just about all sea water, it not backflushed **** from the pump into the inlet which causes the problem.

 

[vyv_cox]

No, it's the stale seawater which is why it smells of rotten eggs and not sh*t.

It most definitely is not. I tested seawater samples over a period up to a month, in warm, cool, light and dark conditions. Samples were sealed for 1, 3, 7 and 14 day intervals, after which they were decanted and sniffed by two people. Finally I left a bottle in the engine bilge for a month. Not a single one smelt of H2S, or anything else. The whole experiment was written up and printed in YM about four years ago.

We are not talking about whole turds in the inlet pipe, the amounts are small, transferred into the inlet side of the piston by scraping the O-ring up and down the walls, then transferred through the valve by poor sealing. Anaerobic bacteria multiply at a huge rate in these conditions, generating hydrogen sulphide. That's why the water doesn't smell of sh*t.

Edit: I realise that a photo does not prove the absence of a smell but here is a pic of the bottles used for the tests. As the writing on the bottles shows I also did some with full bottles and some only half full to find what effect air had. Answer - none.

 

[sailorman]

It most definitely is not. I tested seawater samples over a period up to a month, in warm, cool, light and dark conditions. Samples were sealed for 1, 3, 7 and 14 day intervals, after which they were decanted and sniffed by two people. Finally I left a bottle in the engine bilge for a month. Not a single one smelt of H2S, or anything else. The whole experiment was written up and printed in YM about four years ago.

We are not talking about whole turds in the inlet pipe, the amounts are small, transferred into the inlet side of the piston by scraping the O-ring up and down the walls, then transferred through the valve by poor sealing. Anaerobic bacteria multiply at a huge rate in these conditions, generating hydrogen sulphide. That's why the water doesn't smell of sh*t.

This doesnt happen with the Lavac system. we get no smells at all

 

[nigelmercier]

It most definitely is not. I tested seawater samples over a period up to a month, in warm, cool, light and dark conditions. Samples were sealed for 1, 3, 7 and 14 day intervals, after which they were decanted and sniffed by two people...

I'm not convinced. I have a brand new heads that has never been used, but it still has the smell from the inlet. The pipes have been treated with Milton, which cures the problem for the duration. However, next time I flush it (when I open up the boat) it smells again. It's the only manual heads on the boat, in a cabin we don't use, kept for power failures.

Of course, in a marina there may be a higher concentration of faecal matter in the water anyway. Don't eat the mussels!

At least we agree the smell is nothing to do with the outlet.

 

[vyv_cox]

This doesnt happen with the Lavac system. we get no smells at all

Nor with our Jabso LITE. There is no cross-contamination across the pump. I have heard of some people with Lavacs who did experience smells but suggest that this may be because the draw in what has been discharged in small amounts. I would have liked a Lavac but do not have the space for the pump.

 

[vyv_cox]

I'm not convinced. I have a brand new heads that has never been used, but it still has the smell from the inlet. The pipes have been treated with Milton, which cures the problem for the duration. However, next time I flush it (when I open up the boat) it smells again. It's the only manual heads on the boat, in a cabin we don't use, kept for power failures.

Of course, in a marina there may be a higher concentration of faecal matter in the water anyway. Don't eat the mussels!

At least we agree the smell is nothing to do with the outlet.

I cannot comment on the quality of the water that you draw into your toilet. If there are bacteria in it when it comes in then they will proliferate. My tests were carried out on water collected from the open sea, which as far as my nose could ascertain contained no bacteria over various typical periods of time.

 

[Otter]

Forward heads is number 1's and 2's - bad egg smell on first flush. Aft heads is strictly number 1's only - never a bad smell on any flush, pipes sit for weeks sometimes with seawater in them.

 

[Interlude]

I moved to fresh water flushing (Jabsco manual) several years ago - smelly heads no more. Being lazy, we use the hand shower from the adjacent sink to fill the bowl after pumping out, and pump this through the hose to he holding tank. Even when the joker valve leaks, (which is way too often even a few weeks after replacement) the back flow is odour free. Adding another freshwater tank for flushing is on the long list of things to do, but remains on the bottom of the list!

 

[PCUK]

It most definitely is not. I tested seawater samples over a period up to a month, in warm, cool, light and dark conditions. Samples were sealed for 1, 3, 7 and 14 day intervals, after which they were decanted and sniffed by two people. Finally I left a bottle in the engine bilge for a month. Not a single one smelt of H2S, or anything else. The whole experiment was written up and printed in YM about four years ago.

We are not talking about whole turds in the inlet pipe, the amounts are small, transferred into the inlet side of the piston by scraping the O-ring up and down the walls, then transferred through the valve by poor sealing. Anaerobic bacteria multiply at a huge rate in these conditions, generating hydrogen sulphide. That's why the water doesn't smell of sh*t.

Edit: I realise that a photo does not prove the absence of a smell but here is a pic of the bottles used for the tests. As the writing on the bottles shows I also did some with full bottles and some only half full to find what effect air had. Answer - none.

We'll have to disagree on this one. I'll stick with practical experience over many years and with toilets that are impossible to cross contaminate.