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Thetford cassette water supply hose


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My old water pump started leaking yesterday, so I replaced it today with a Jabsco with a slightly higher pressure than the old one (25psi rather than 20). This has resulted in a pinhole leak in a reinforced black hose in my cassette installation.  It runs about a foot from what looks like a non return valve into the back of the cassette mount where it links to a PVC hose that supplies the flush.  As best I can measure it seems to be 21mm OD pushed over 17mm brass fittings. Photos below:

 

Is there any particular type of hose that I should be looking for as a replacement - also I am not readily finding water hose of this size, so a supplier would be useful?

 IMG_20220806_192627973.jpg.9114e2da141e97f82538369ce6aed1eb.jpgIMG_20220806_192718653.jpg.1302cfbd95f0eb0d96f3e91c047a242a.jpg

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Thanks all.

 

I wanted to get the water back on to do the washing up before going home so I ended up in Halfords as Midland was closed. 

 

16mm seems a tiny bit too large, but OK for the moment while I see if I can find something a fraction smaller. The next size down from online suppliers I've looked at is 12.7 or 13mm which I think might be difficult to fit.

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What may be partially responsible for the leak developing over time is that it is using a cobbled together adaptor from Yorkshire plumbing fittings, by the look of it, to go from the 5/8" (~16mm) hose to the 3/8" hose used in the Thetford. As the hose ages, this sort of thing will start to leak. Better would be a proper adaptor with fir tree barbs. Something like

https://www.ebay.co.uk/itm/172863849458

Found using a search for 5/8 3/8 hose reducer on ebay. Lots of other options there for a few quid, in plastic, or brass. A properly sized jubilee clip on each and it will last for many years.

Similarly, where it connects to the boat plumbing, you want a 1/2"BSP to 5/8 hose tail. Something like https://www.ebay.co.uk/itm/120861755405 . Again, lots of alternatives in different materials.

On my boat, I have the plastic pipe going nearly all the way to the Thetford, a 15mm pipe to 1/2"BSP fitting, a 1/2"BSP to 3/8" hose fir tree fitting. Much simpler than your  arrangement, with fewer joints and less opportunity for leaks. An out of focus pic. Must do some dusting back there! There is a short length of copper pipe between the plastic and brass right angle turns, just because that is easier to use with a compression fitting.

IMG_20220808_081408.jpg.a48955dedf8ef6559ba346efbbe9106f.jpg

 

Jen

Edited by Jen-in-Wellies
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7 hours ago, Jen-in-Wellies said:

What may be partially responsible for the leak developing over time is that it is using a cobbled together adaptor from Yorkshire plumbing fittings, by the look of it, to go from the 5/8" (~16mm) hose to the 3/8" hose used in the Thetford. As the hose ages, this sort of thing will start to leak. Better would be a proper adaptor with fir tree barbs. Something like

https://www.ebay.co.uk/itm/172863849458

Found using a search for 5/8 3/8 hose reducer on ebay. Lots of other options there for a few quid, in plastic, or brass. A properly sized jubilee clip on each and it will last for many years.

Similarly, where it connects to the boat plumbing, you want a 1/2"BSP to 5/8 hose tail. Something like https://www.ebay.co.uk/itm/120861755405 . Again, lots of alternatives in different materials.

On my boat, I have the plastic pipe going nearly all the way to the Thetford, a 15mm pipe to 1/2"BSP fitting, a 1/2"BSP to 3/8" hose fir tree fitting. Much simpler than your  arrangement, with fewer joints and less opportunity for leaks. An out of focus pic. Must do some dusting back there! There is a short length of copper pipe between the plastic and brass right angle turns, just because that is easier to use with a compression fitting.

Jen

 

Thanks, that's a useful suggestion for a more permanent fix than I have just now.  When faced with failures that need to be fixed quickly I probably err on the side of replacing like for like, rather than thinking about whether there's a better solution.

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