Basin/Bath Blockage Conundrum

[redlos]

Thanks for the warning, I know.

 

[Madrab]

One shot - Concentrated sulphuric acid - not withstanding the injuries someone can sustain when plunging with one shot sitting in the waste by pulling it back up onto themselves or when using a wet vac etc. There is a lot of damage that it can cause to the waste system and drains by the heat generated and it's extremely corrosive nature.

It is a very narrow set of circumstances where it should ever be considered.

Any DIY'er thinking about using One Shot or any concentrated drain cleaner should be very aware that it can be highly dangerous. When it doesn't work and then the professional arrives, please tell them it has been used and keep the container so they can see what's been tried.

 

[HERTS P&D]

Let alone people using bleach beforehnd!

Andy

 

[dilalio]

Let alone people using bleach beforehnd!

Andy

Or a bucket of really hot water afterwards!
Me!
no!
never!
Just something I heard!

 

[redlos]

Thanks for the advice. Cos of other things I use with crafts etc. I’m in the habit of wearing all my gear that I wear while using resin, when using One Shot. Looks a bit silly but I’d rather be safe than sorry.
My nephew is a plumber and I remember he suggested it as a very last resort a couple of years ago and said much as you’ve said. If I hadn’t had visitors coming I would have persevered with less problematic methods.

Hope you weren’t injured Dilalio!

Thanks All for the Advice.

 

[dilalio]

Hope you weren’t injured Dilalio!

No. Thankfully. But it meant a lot of clear up in the gents at the office I was attending!

 

[Madrab]

Worst case I ever came across with one shot was where client had added most of a bottle of it into the blocked bath waste run full of water and left overnight, it reacted & heated up the waste pipe to the point it went soft and pulled itself out of the trap, one shot and water then leaked down through the floor through the ceiling and into the kitchen below. The fluid lifted the surface off the kitchen worktop and down onto the the laminate floor and then wrecked that.

Insurance didn't want to know, as the client shouldn't have been using it. They were lucky though as their daughter's bedroom was beside the kitchen and there was staining on her roof above her bed but the kitchen ceiling had leaked first.

 

[redlos]

Oh goodness

 

[Madrab]

Oh goodness

Please don't take that as a personal slant, as you suggest you were/are aware that it can be dangerous.

This is more for other DIY'ers that may be on the site and reading this and are maybe not be aware about just how dangerous a lot of drain cleaners can be to them & theirs.

 

[redlos]

Didn’t take it as anything other than what it was. To be fair I probably should have added a warning note when I mentioned using it. Better to be warned again, for everyone’s sake.

 

[redlos]

Just one more thing. If the gurgling is coming from the bath when the basin empties, should an anti syphon trap (AST) be fitted to the basin to stop that or is there an anti syphon for bath waste ? I guess there’s not much room for a bath AST.

So, while the water is draining quickly now from the bath (which was the original problem) when I run the basin tap it still gurgles backs up into the bath waste a little if not quite as far as coming up into the bath now. Would a non return valve help here? If I fitted one to the bath waste would that mean the basin would run slowly, in not being able to back up into the bath?

 

[Madrab]

Just one more thing. If the gurgling is coming from the bath when the basin empties, should an anti syphon trap (AST) be fitted to the basin to stop that or is there an anti syphon for bath waste ? I guess there’s not much room for a bath AST.

yes, you need to vent the waste upstream of the slug of water exiting into the main run, an antivac trap will do that. Just remember to clean it periodically. You do get anti vac bath traps but you need to have the clearance as the valve sits on top of the outlet section.

The reason for the water entering the bath waste is due to the water always following the path of least resistance.

This can be down to a few things - still a restriction downstream of the where the basin connects to the mains waste, so the initial water surge travels upstream - the fall of the waste run isn't enough to ensure the initial outflow all heads downstream - The waste would ideally increase to 50mm at the branch of the basin waste if the fall isn't suitable.

 

[dilalio]

There’s a soil stack running internally to the right of the toilet and I believe this vents out through the roof.

Does it vent through the roof?
Does it have an open vent? (SVP - soil vent pipe)?
Or an AAV (Air Admittance Valve)?

As your bath and basin empty (and Bog... but that looks like its separately connected to the stack), a "volume" of liquid travels down the pipe.
In front of this volume of liquid is a volume of air (technically still a fluid) which needs to be pushed out of the way.
This is what an SVP is for and is why they need to be above the eaves of the roof... the bad air has somewhere to escape to atmosphere and allow the liquid waste to continue its journey to the seaside (Oops! I mean Sewage Treatment Works!).

A lot of installations, incorrectly incorporate AAVs only and no SVPs.
AAVs allow air in but not out, so the air in front of the volume of liquid has nowhere to go but upstream, trying to get past the liquid that's coming down the same pipe!

This is what causes 'gurgling' in the 1st instance.
It also slows down the velocity of the waste liquid travelling down the pipe.
This leads to solids in that liquid, coming out of suspension/solution to be deposited at the invert of the pipe.
This leads to blockages.
This leads to water backing up in the lower receptacles such as baths, shower trays etc.

Add to this, the often sub standard, waste system designs, where the only fall on the pipe was the fool who fitted it, and you can see why millions of bottles of drain cleaner are sold each year... and eventually deposited into the environment, despite costly attempts to remove it.

Not a lot you can do, easily and inexpensively, if your waste system is of poor design and/or construction, however.. its good practice to regularly fill baths, basins and sinks with just clean, hot water and let them go... dishwashers and washing machines on an empty cycle and a bucket of hot water down bogs too... it all helps flush the system through.

Don't get me started on close-couple WCs with a 3/6L flush when our sewers were originally designed for one high level 11L cistern, per house!

 

[dilalio]

yes, you need to vent the waste upstream of the slug of water exiting into the main run, an antivac trap will do that. Just remember to clean it periodically. You do get anti vac bath traps but you need to have the clearance as the valve sits on top of the outlet section.

The reason for the water entering the bath waste is due to the water always following the path of least resistance.

This can be down to a few things - still a restriction downstream of the where the basin connects to the mains waste, so the initial water surge travels upstream - the fall of the waste run isn't enough to ensure the initial outflow all heads downstream - The waste would ideally increase to 50mm at the branch of the basin waste if the fall isn't suitable.

FFS Rob!
You posted that while I was still trying to write, creatively!!

 

[Madrab]

You posted that while I was still trying to write

Apologies D, isn't it really feckin frustrating when in the middle of elaborate explanation of things the 'there are more posts to display' message pops up and then realising that someone has got in there first.

In saying that, you covered the 'AAV on the stack point' and others that I didn't so between us both I think we covered every eventuality