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Replacing toilet pipes

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Raimondo View Drop Down
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    Posted: 28 October 2025 at 21:17
Hi everybody,

I would like to replace the toilet pipes in the aft head, but I don't know how to reach the hose clamps that keep the pipes attached to the waste tank, see the 2 pictures:


I did't find an easy way, what do I need to dismantle?
If it is too complicated, I'm thinking to make a hole and install an inspection  hatch here:

Inspection hatch like this one:


What do you think?

Raimondo
400e #499 2009 "Cricca 4" ITA16254
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Ratbasher View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ratbasher Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2025 at 06:19
I recently changed mine - with great difficulty.  It was a horrible job, requiring me to get my head and one shoulder through the small door below the sink and then twisting into positions I'd long thought myself incapable of.  Not to mention the inevitable leakage.....I'm still traumatised by the experience.

Without any doubt, were I do to do the job again I would certainly cut an access hatch in the position you describe.  Also consider fitting something that might make the space more usable: Force 4 Locker with Drawers & Lock | Force 4 Chandlery
H400 (2008) 'Wight Leopard' Gosport, UK
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Mark Pullen View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark Pullen Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2025 at 15:16
I considered a similar job on my 350. However, was then persuaded to clean the mineral deposits with acid. I checked with an endoscopic camera. It took a couple of doses of approximately 5% dilute hydrochloric acid left for 30 minutes each time. Worth considering, if struvite/mineral deposit is a motivation for the replacement.
Mark
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sgrhma2 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sgrhma2 Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2025 at 15:44
Like Ratbasher, I changed my pipes (370) and found the experience rather scaring to the senses! It can be done through the hatch under the sink, but is difficult. There are a number of posts on this sight with pictures of a hatch fitted for the purpose of changing the pipes.
Since changing the pipes a golden rule on my boat when anyone uses the toilet is to have a minimum of 15 pump cycles (a cycle of the pump is an up and down stroke) of flushing when the toilet is used. When servicing the toilet since introducing the rule, there is a huge improvement in the reduction of calcification in the pipe.

Hope this is useful 
Simon
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Mark Pullen View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark Pullen Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2025 at 16:02
Struvite is formed of ammonia and phosphate (in Urine), magnesium (in seawater or cleaners), heat and a stagnant, alkaline environment. I too had problems with the pipes and black water tank. In order to reduce the build-up I've ask crew to pump 15 times and also try to maintain a neutral or slightly acidic environment in the tank by adding a squirt of vinegar or Viakal to the heads each morning. So far, so good.
Mark
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BamBam View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BamBam Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2025 at 17:33
We still have this job on our to-do list. If you're lucky, you might be able to reach the clamp through the upper wooden paneling. Otherwise, the inspection hatch is the better option. In the worst case, it's a job for the ship's mechanic.

If you prefer the cleaning option:
we used baking soda and citrus acid, but only for a short period of time, to loosen the built up. You will then encounter small "metallic plates and pieces" during your 100s of pumps Big smile


Edited by BamBam - 29 October 2025 at 17:38
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Mark Pullen View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark Pullen Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2025 at 18:27
I've done a lot of research into struvite, having had problems with a blocked holding tank. Citric acid works and brick/patio cleaner. Trick is to find something cheap in sufficient quantities to fill the pipes and tank at a high enough concentration. Then leave for a relatively short period to avoid over doing it. Then use an endoscope to check the result.
Mark
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Wayne's World View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Wayne's World Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2025 at 19:26
Changing to fresh water flushing reduces the formation of the deposits. Also stops the stale sea water small. 
Wayne W
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Martin&Rene View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Martin&Rene Quote  Post ReplyReply Direct Link To This Post Posted: 30 October 2025 at 13:02
Mark is right.  Do not leave any fluid in for a long time.  I had just filled the system with just vinegar and unfortunately a change in circumstances meant that we did not get back to the yacht for 3 weeks.

The vinegar had distorted the rubber joker valve and the pump seals, so they had to be replaced.
Martin&Rene Hanse 341 Dipper Wheel steering, 3 cabin layout, normally based in Scotland
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Ratbasher View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ratbasher Quote  Post ReplyReply Direct Link To This Post Posted: 30 October 2025 at 16:22
Unfortunately, long and bitter experience tells me that the only guaranteed solution is to do as Wayne suggests and use fresh water.  However, while that might do-able when alongside, for those of us without massive water tanks or a watermaker it's simply not an option if you spend long periods at sea or moored/anchored.  Watermakers themselves bring their own problems anyway, as do some of the products often thrown into the toilet system.  'Practical Sailor' magazine carried an excellent article a while ago researching additives and found them mostly useless anyway, particularly vinegar.  I've got 'trudesign' hull valves and while they might resist acids I don't want to risk the boat testing that claim, particularly given the strengths necessary to achieve any meaningful result.

Like many others, our head is flushed >18 times yet while this certainly delays the inevitable by a large margin, sooner or later the pipe is going to need to be replaced no matter what gunk is thrown down there.  Raimondo is quite right to ask the question and my answer is most definitely to cut away an access panel.    That said, a combination of multiple flushes and fresh water when alongside might last out your period of ownership if you're not virtual liveaboards as we are for the season.

Commenting in the bar after my particularly traumatic experience changing the pipes via the small hatch, a fellow Hanse owner renamed my boat 'sh*te Leopard'.....Unhappy
H400 (2008) 'Wight Leopard' Gosport, UK
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