ᐅ Bathroom smells like a drain

Created on: 4 Sep 2014 12:39
M
marcbytelle
Hello, about two years ago our house was handed over, and shortly after, an unpleasant smell started to appear in the bathroom from time to time.

At first, I didn’t pay much attention to it, since during the drying phase it was normal for rooms to occasionally be damp. But now, honestly, this smell has been bothering me for months.

It can be detected near the washbasin and more recently also in the shower and bathtub right by the drain. A slightly rotten, musty, or moldy odor fills the entire bathroom after a while and spreads throughout the whole house (bungalow) when the door is open.

The plumbers have already been, but they couldn’t find anything. The trap at the sink is working, also in the shower – nothing is getting siphoned out. The drain piping at the washbasin has even been replaced.

Over the weekend, I also thoroughly cleaned the flat shower tray using cleaning agents… but the musty smell was back yesterday.

I really don’t know what else to do. I have already gone through various forums and so on.

An extensive cleaning, with or without chemicals, has unfortunately not helped so far.

Do you have any ideas?

Could it possibly be related to the roof ventilation?

Can sewer gases rise back through the trap water due to overpressure or underpressure?

Regards
M
marcbytelle
4 Sep 2014 13:10
There is no drain directly in the floor.
You probably mean something like not having a shower tray and standing directly on the tile, with a grate and the drain underneath?

Regards
K
klblb
4 Sep 2014 13:13
No, I’m not talking about a drain in the shower, but one located elsewhere in the floor of the room. It’s quite useful, for example, if the washing machine (if there is one in the bathroom) leaks or bursts. In our rental apartment, there is such a drain, and I have to pour water into it every few weeks; otherwise, there’s no longer any water seal left.
M
marcbytelle
4 Sep 2014 13:15
No floor drain is installed.
In the bathroom, I have a toilet, washbasin, shower with a low-profile tray, and a bathtub.
D
DerBjoern
4 Sep 2014 13:30
Do you have a ventilation system? Some acquaintances had the same problem at first until they discovered that the mechanical ventilation with heat recovery was connected incorrectly. Both fans were exhausting air, creating negative pressure inside the house, which caused air to be drawn in through the drainage vent stack.
M
marcbytelle
4 Sep 2014 13:37
No, we do not have a ventilation system.

- Cooker hood in the kitchen with a filter (air is not vented outside)
- Chimney is present / fireplace not yet connected
- Heating boiler is located in the utility room

Otherwise, nothing unusual.
lastdrop4 Sep 2014 13:38
Even a range hood with external venting can siphon a trap dry, at least to the extent that air passes through from below.