Wet floorboards around toilet
Wet floorboards around toilet
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Discussion

_Jonesy_

Original Poster:

53 posts

133 months

Tuesday 9th December 2025
quotequote all
I ve just ripped up our bathroom lino to investigate a damp patch on the kitchen ceiling below. It turns out the floorboards surrounding the toilet are completely sodden - water comes out when I press them with a screwdriver, so assuming this has been happening for a little while.

I don t think the waste is leaking - there s no bad smells or mould. The joint between the cistern and the toilet supply is very slightly leaky but it doesn t seem to be causing the damage which is further forward and separated by the panel that conceals the toilet. I m at a bit of a loss where the water is coming from - any suggestions gratefully received!


crossie

227 posts

267 months

Tuesday 9th December 2025
quotequote all
we've had 2 cracked toilets

Looked perfectly normal but would drip a little every now and again

MG-Steve

731 posts

222 months

Tuesday 9th December 2025
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If there's a leaky joint that is probably the cause.. Fix the leak and see if it solves the issue?

jimothyc

850 posts

114 months

Tuesday 9th December 2025
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Stand closer to the toilet when you’re using it 🤣

wolfracesonic

9,243 posts

157 months

Tuesday 9th December 2025
quotequote all
Aim better! Or buy some drain dye, put some in the bowl, flush and see if anything shows up; if not try some in the cistern and see if the problem is there.

Bill

58,736 posts

285 months

Tuesday 9th December 2025
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You'll be amazed how far it tracks. We had a leaking bog and the the water had got under the engineered floor 1m into the next room.

allegro

1,335 posts

234 months

Tuesday 9th December 2025
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depends on your loo but I did one recently that had been leaking for 15 years. installer had nicked the flexy hose and it leaked with every flush
floor boards were like tissue paper and the top inch of the joist was the same.
good job the owner was 7 stone!

Huzzah

29,029 posts

213 months

Tuesday 9th December 2025
quotequote all
crossie said:
we've had 2 cracked toilets

Looked perfectly normal but would drip a little every now and again
I've had this too.

Cold

16,724 posts

120 months

Tuesday 9th December 2025
quotequote all
Out there suggestion - if the flush valve is leaking, the water in the tank is constantly topped up and therefore never gets up to room temperature meaning condensation can form on the outside.

Little Lofty

3,887 posts

181 months

Tuesday 9th December 2025
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I’d fix the leak you already know about first, it’s amazing how water travels, especially trapped under lino. If that doesn't cure it I would be checking the pan connector next.

Russet Grange

3,097 posts

56 months

Tuesday 9th December 2025
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I'd be very confident that the pan connector is the problem.

Beetnik

577 posts

214 months

Tuesday 9th December 2025
quotequote all
Russet Grange said:
I'd be very confident that the pan connector is the problem.
This

miroku1

417 posts

137 months

Tuesday 9th December 2025
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It’ll be something to do with the flush pipe from the cistern , always is , they a terrible design, wouldn’t have that garbage In a house, cheap tat

Baldchap

9,629 posts

122 months

Tuesday 9th December 2025
quotequote all
Beetnik said:
Russet Grange said:
I'd be very confident that the pan connector is the problem.
This
yes

ric19

88 posts

148 months

Tuesday 9th December 2025
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I had something similar on my previous house, what it turned out to be, was that the steam from the shower in the same room was condensing on the toilet tank that was in a boxed off section like yours, and then the beads of water were falling off the tank onto the floor.I ended up putting some sheets of polystyrene around the tank to isolate it and it worked..

Xcore

1,530 posts

120 months

Tuesday 9th December 2025
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Flush cone probably. Whip the panel with the button on and have a look/feel.

alangla

6,768 posts

211 months

Tuesday 9th December 2025
quotequote all
Beetnik said:
Russet Grange said:
I'd be very confident that the pan connector is the problem.
This
Yep, this. I managed to cause an identical small leak with a similar result of sodden floorboards by replacing a knackered syphon and managing to disturb the cistern to pan coupling at the pan end. Tiny amount leaked per flush, but it built up under the floor in a similar fitted bathroom to yours.

_Jonesy_

Original Poster:

53 posts

133 months

Tuesday 9th December 2025
quotequote all
Thanks everyone for some really helpful replies. I ended up stripping the whole unit out and the leak was worse than I realised.

Xcore said:
Flush cone probably. Whip the panel with the button on and have a look/feel.
This was right! Thanks. Ended up replacing the whole cistern and all the seals as it had clearly been bodged over the years with various sealants (and a load of paper shoved under the back panel. No leaks now, will let the floorboards dry out and see what happens!

Hoofy

80,099 posts

312 months

Wednesday 10th December 2025
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Yeah, that doughnut might need replacing. Hidden cisterns look great but late leak detection puts me off them, having had a cistern leak in different places (1 doughtnut, 1 inlet pipe joint). If I had it hidden away, it would have taken longer with a bigger pool of water to discover much later... as you have found!