Any plumbers on here?

X5Sport · Post by **X5Sport** » Sat Mar 14, 2026 12:06 pm

Folks, I need a bit of advice.

We’ve recently had a new ball-valve fitted to our main cold water tank in the loft. The plumber that did it managed to drop fibreglass loft insulation into the tank whilst the cold taps upstairs were running so as to get the water level down.

Unsurprisingly both cold taps promptly blocked! The company came back and have spent several hours trying to sort the issue. One tap has been cleared by removing the fibreglass from the tap cartridge and things are working again. However the flow from the second tap is still about 1/3rd of what it should be. The plumber is telling me that the only fix will be a complete replacement of the pipe to that bathroom.

Doing that means removing built in furniture, lifting carpets and lifting the chipboard flooring. The alternative would be to pull every ceiling along the route!

Is there any other way of cleaning a pipe, such as gently pumping water backwards to try and dislodge the (probably fibreglass) that will have caught on a bend somewhere along the 20ft or so of 15mm copper? Has anyone tried this and had any success? I’m obviously wary of applying a lot of pressure in case that makes things worse (such as by blowing a joint!). If I can get just enough to dislodge the rubbish, even if it’s enough to allow it around the bends then job done.

I’ll be talking with the parent organisation to the plumbers to see what they plan to do given it was their employee who caused the whole issue. I’m a lot less than impressed!

Leslie · Post by **Leslie** » Sat Mar 14, 2026 2:35 pm

I'm not a plumber but I think id be getting some clothes line which would be flexible but still rigid enough to go through and not damage the pipe as its plastic coated and and sticking it down the pipe either end if need be and see what pops out before it be considering replacing pipe. I believe they can cut some discrete holes now and feed it through so it wont be as big a job as it sounds ( goodluck)

X5Sport · Post by **X5Sport** » Sat Mar 14, 2026 6:23 pm

An interesting thought. The ‘challenge’ being it’s a single pipe from the tank but it feeds two toilets and two hand basins which are in opposite directions. My estimate is at least 5 90° bends and some ‘T’ joins. We don’t know the exact route the pipes have taken either. I know there are radars now that can find (and graphically display) an image of the pipes, wires, purlins, wood beams etc.

The belief being some of the fibreglass has hung up on one of the joints/bends.

It might be possible to get a ‘mouse tail’ (it’s what we called them in the workshop I worked in 40 years ago) made of plastic and similar to a washing line and see if that can get through.

I’ve also seen that back flushing using a hose reel might work as long as the tank is emptied. I have a submersible pump that can also possibly be used to provide pressure. If all the other pipes are closed off then it ought to be possible to force (or even release) the hang up and if it slows forward, clear the pipe.

Thank you for the idea, I am pondering and will see what my energy supplier comes up with. It was their subbie who caused this in the first place.

Leslie · Post by **Leslie** » Sat Mar 14, 2026 6:46 pm

It can't be badly stuck wouldn't take much to free it , there is probably a union can be undone like under the sink etc and get a hose on or even one of those sink plungers on the tank bottom outlet to force it through with the tap off , putting insulation in the tank instead of a plug was a bit of a silly idea though !
plan B compressed air and prepare for a mess at other end

marti · Post by **marti** » Sun Mar 15, 2026 9:55 am

I've done a lot of plumbing, as one tap is working I wouldn't blow back anything to the main tank as you might push the obstruction to another place as the pipework is linked to your other feeds, do you have an isolation valve to said tap? (chrome valve with flat head screw in the middle), undersink, if so turn that off, normally half turn, so no flow, remove the pipe from top of valve to tap...get a hose and bucket, you will need a small 3" bit of cooper pipe, put that in valve top and do up, put a bit of hose on the pipe in to the bucket, turn on valve and see what the flow is like, I reckon the blockage is in the tap even if they have cleaned the cartridge as tap blockages can be in other parts of the tap assembly......

X5Sport · Post by **X5Sport** » Sun Mar 15, 2026 1:21 pm

We’ve done that bit, and yes the worry is back flushing could move the issue. The feed only goes to two toilets and two hand basins. The bath feed is on 22mm.

All tap lines and valves were opened yesterday. Fibreglass was found in one (and cleared) but the second one is clear. The obstruction if further back up the pipe, possibly stuck on a bend or T-joint. I suspect it might actually be quite close to the handbasin feed as the toilet is filling pretty well.

The original builder did not fit stop valves, and the plumber fitted those on all the hot/cold pipes as part of their repair attempt. The obstructed run is about 25 feet of 15mm. They also fitted a hose and attempted letting it run to a drain. Sadly, nothing came out.

It may clear itself in due course, but nothing yet.

. I could try a bit of plastic line as suggested and see if it pops out.

marti · Post by **marti** » Sun Mar 15, 2026 2:15 pm

Okay, in that case if the cistern is filling fine then as you say its near to basin...so two options remove a bit of floor near to the basin as the feed for cistern will branch off the basin feed or via versa or remove a section of ceiling (easiest option) below that area and then they can cut the pipe there at the intersection where it branches off to the basin/cistern and replace, they are liable to replace the ceiling etc...they will have trade insurance, so let them sort it

marti · Post by **marti** » Sun Mar 15, 2026 2:27 pm

There is a method which a colleague of mine did for a sludge problem, basically you need a vacuum cleaner wet/dry one and with lots of "GOOD" quality gaffer tape, you basically disconnect the tap cold supply at valve (turned off) gaffer tape hose up to pipework,…hoover on full blast open valve....basically suck it out..

X5Sport · Post by **X5Sport** » Sun Mar 15, 2026 2:55 pm

I’ve got a wet/dry vac. That might actually work as I’m pondering whether increasing the pressure (of the water head) by lowering the pressure in the pipe might work. I think I can create head pressure whilst it not enough vacuum to collapse the pipes so it might indeed be worth a try.

Very creative of your colleague. I like that.

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