Very slow draining bath.

[Serval]

Got a bath that which drains extremely slowly, to the point where if taking a shower, the bath fills up. It's been like this from the time I got the place. (About 9 years ago)

It's got a 40mm (I think) waste that runs about 2.5 metres until it exits the building then runs another few metres before joining the main stack.

Ive removed the trap on several occasions over the years and it's been completely clean every time. Have tried plunging and using various unblocking products. All of which have made no difference.

The drainage rate hasn't improved but equally it hasn't got any worse which I was expecting ho happen if there is some obstruction somewhere in the pipe, even more so as the place has been rented out to various tennants over the years.

The sink and toilet also go to the same vertical stack on different lines all of which drain fine so don't think there's a problem on the main stack or in the manhole.

Could the issue be that part of the pipe work for the bath doesn't have sufficient fall to drain properly?

Short of pulling up the floor boards and carpet to check for the correct fall in the pipe is there anything else I can do to check any other potential causes?
Tia

 

[ShaunCorbs]

If the shower fills the bath would say the horizontal bit is blocked / restricted

 

[Serval]

Any other suggestions? Given plunging/unblockers have not been successful so far.

I've seen those drain snake devices but am reluctant to use that for fear of it getting stuck or breaking around one of the 90 degree bends

 

[snowhead]

On my version of your photo, if the bath waste is as identified then the best way if you can access that pipework is to remove the access cap circled yellow, use a snake / flexi and push it down towards the stack first, there's only one bend to get around so it shouldn't jam.
Twist the snake as you push in and when pulling out.
If there's no blockage, then push it back to the inside towards the bath, twisting again, if you feel it hit a blockage pull back then push forward again.

If you're brave, get someone to start filling the bath when you've taken the access cap off, if water comes out fast, then the blockage is down towards the stack, if it comes out slow then it's towards the bath.
If you get wet then you weren't quick enough putting the cap back on.

 

[Serval]

On my version of your photo, if the bath waste is as identified then the best way if you can access that pipework is to remove the access cap circled yellow,

Yes that's it and the basin waste is to the right.

Good should. I can get access via the ground floor and will give that a try. Hopefully it works.
Won't be anywhere near it when filling and draining the bath though! 😀

Thanks!