Clogged bath waste (edited)

[ac24]

I've finally managed to remove the bath panel tonight, as the tub has been draining incredibly slowly. I thought this was due to soap and hair build up so was expecting to have to pull a load of crap out. Instead the trap was clean. But I discovered a few things which have been confusing me.

Firstly the plumbing under the tub is a bit odd, there is a normal p trap and then a second u bend made out of elbows under the bath. Could this be because there used to be a tub with a drain in the middle?

Weirder still, when I disconnected the overflow Flexi pipe to clean that, I noticed a constant trickle of water backing up and into the bath waste into the tray underneath. See video.

What the heck is going on? The bath and sink share some common plumbing, and there has started to be a lot of gurgling as the sink drains. The drainage from the bath has never been great, but the backing up is getting progressively worse over the last few months.

 

[Madrab]

That's Not a normal P trap, that's a shallow bath trap and unless the waste is heading out to a hopper or open gulley then it's the wrong trap for a bath. If it's into a stack then it should really be a min of a 50mm seal on the bath trap, that one is only 19mm. The trickle may be be down to not enough fall on the pipework immediately downstream of the trap and there is just enough water in there to run back up through the trap.

The pipework under the floor looks like someone has attempted to make up a significant homemade running trap just using pipework, possibly because they weren't able to fit a trap to what was there before, sometime the case with floor standing baths that use flexi's straight from the waste. Problem with a home made running trap like that is it can get blocked/restricted with no way of servicing, especially if using elbows rather than all swept bends.

Time for a wet vac to see if that clears things and check all the waste pipe has an adequate fall.

 

[ac24]

Thanks. I'll see if I can lay my hands on a wet vac. Sounds like there is some kind of blockage in there from what you suggest? I do have a drain snake and made it around a couple of bends but didn't extract anything significant.

The trap drains out into a stack, yes. Actually the same pipe connection to the stack serves the sink too. We'll get the bathroom done sometime in the next couple years, so don't mind if it drains slowlyish, but right now it's terrible.

Edit:I remember filling the bath and letting it drain before I starting messing with the overflow waste so you might be right there.

 

[ac24]

@Madrab would you recommend swapping the 19mm trap for a 50mm, preferably with cleaning eye?

Edit: scratch that, there's no depth for it

 

[Madrab]

same pipe connection to the stack serves the sink too

When you say sink do you mean a kitchen sink or is it the basin?

If there is that homemade seal then there's no real point in adding a deeper trap. it would have been better if the culprit had used compression fittings, then at least it could have been taken apart. If it was me then I'd be looking to cut all that out and connect something smarter in there, say a waterless or remote trap.

 

[ac24]

Thanks, appreciate the reply. The bath and bathroom basin share a common pipe into the stack. The sink drains well and without issue, but does cause a lot of gurgling which I imagine could be caused by the bath blockage.

I'll see if I can pick up a cheap wet vac and clear the blockage, and then probably a cover on the bath drain to block hair/hairbands etc. This house is full of surprises...

 

[ac24]

Embarrassed to say that a couple bottles of Mr Muscle drain unblocker did the trick overnight.

I think the bottles recommend a small dose, but with my plumbing arrangement it wasn't getting anywhere near the issue. Once the existing water was displaced the gel did a great job.

 

[dilalio]

All those exotic bath oils over the years don't do wastes much good and eventually coat the inside of the pipe, which builds up. More so when there's little fall on them.

Anything that will dissolve/cut through that oil and grease, used regularly helps them run clear.

Better that they are installed correctly, rather than relying on VOCs being poured into our sewer system for the water board to treat.

Unfortunately, there's millions of badly connected wastes out there.

 

[ac24]

Definitely. A plughole strainer is on order and a regular kettleful of the hot stuff should avoid the same issue.