The higher wet point is not necessarily the starting point. The water absorbed up like osmosis. The most damp location is the likely point. Looking at the tile as scale, the height is about sink or toilet flush location I think.

it could also be pipe fittings for water pipes leaking. this usually happen in older homes and accelerated by high pressure.

Contractor can't fix due to mco, Temporarily stop the pipe water in the bathroom now.

This is the bathroom. Any thought where leaking?

Wow, your toilet so beautiful....but time to hack the tiles..hehe

Look like this after cleaning

Sure or not...

this is mold infestation.. spray bleech or vineger on the wall and let it soak.. do a few times then wash the wall...

leave it few days and repeat if still grow after 1 week.
Permanently solve this by putting new oil based gloss coat.
The oil based paint will not allow water to seep onto the wall..

use anti mold paint.
like weather paint something like that.

You need to show/indicate which is the back wall of the mouldy wall.

check the area behind the marked area.

This pic confirm is pipe leaking behind the wall.

Here

This area is here

how is that part built?

try knock on it.........cement or just some plywood screwed into wall then stick some tiles onto it.

check the top white portion...........any missing grout line?

Those are brick. Very solid. No missing grout line.

eitherway.........the waterproofing behind the thing failed.

Based on the picture...
Seems like water seeping through the wall...
Waterproofing failed big....
Sorry to say.. needed to hack the wall & tiles.. to solve long term...

Unscrew the connector at the water heater and wc inlet and roll some white tape on both sides. Hope it is the source of the leak.



This post has been edited by mini orchard: Jun 1 2021, 06:14 AM

If that is the cause usually can see water seeping down from the bathroom side. If don’t see it then very likely not the cause

This post has been edited by slimey: Jun 1 2021, 08:54 AM