I've got a relative with a leaking lead waste pipe. Yes, the correct answer is to take out the lead pipe and put plastic in its place. It's complicated, in that a building extension has been put in, so the outside is not now accessible, except through the ceiling, and even then, access is very limited. The waste pipe runs from the bath and sink in plastic, then goes through the wall in lead, to the cast iron downpipe. The lead pipe has split along the bottom for around 25mm. Only around 4 inch of the lead pipe is accessible as it exits the bathroom. It has happened before. Previously I sprayed some Pro-kleen sealer down the pipe, with limited expectations, but it has lasted 6 months. Rather than using it again, I'd rather put somethng down the pipe that will last longer, before they finally realise it has to be done properly. Any idea of a liquid sealant that could be poured down the pipe to seal the split at the bottom?
Lead pipe leak repair?
Feb 01, 2026
Last reply: 5 months ago
10 Replies
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Is it possible to fit a plastic pipe inside of the lead waste pipe? Plastic waste comes in different sizes.
If vague bends in the run. layflat polythene tube, normally cut and sealed as polythene bags. Pushed over a spring type drain clearer with smoothed over active end, and pushed through your pipe
A repair patch would be the easiest way:
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(since waste pipes are not under much pressure, it should be fairly easy to fix. The denso tape option would be easy and probably last well)
No. The lead is around 50mm. I've tried a 40mm flexi hose with lots of sealant around it, access is terrible, so its very difficult to get it in. It didnt work, it doesnt help that the lead pipe is not straight, it curves round after 300mm.
Something like that may work, I did search for pipe lining supplies, but nothing stood out for small diameter (40 - 50mm) pipes, they are mostly for 110mm drains.
No access to the outside of the pipe, it is in the wall,the split is around 100mm from the entry, so difficult to get to, especially as its in the bottom corner of the bathroom. I only know where it is leaking as I have one of those inspection cameras that can go down pipes[1].
[1]From Toolstation, works far better than expected, not that easy to control, certainly no good at its full extension, but for the price, works very well.
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Plastic waste pipe comes in 32mm diameter. Not necessarily look for lining supplies but just ordinary plastic waste pipe which may fit inside the lead pipe or at least far enough to go past the split.
Possibly flexi pipe suitable cut/modified
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The disadvantage with the latter is that the corrugated ridges may trap soap scum etc. and it may have a thin wall making it not to robust for fitting
Outside of the box Electrical flexible conduit
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It comes in different diameters
It's similar to vacuum cleaner hoses.
Ah, ok misunderstood the circumstance. Being realistic you are going to have some difficulty making an effective repair if you can't get to the pipe at all from the outside. Is there an alternative route you could use for a new pipe?
Whose extension is it? If it’s yours then you need to get back to the builder for not diverting the pipe work and leaving it inaccessible, I take it the down spout is equally inaccessible. If it’s a neighbours extension then again it is his problem to solve for leaving you in this situation.
No, its your fault for not realising that the neighbour will tell you in reality, it is your problem and whatya gonna do about it?
The touching faith people seem to have that other people will obey the law without enforcement always staggers me.
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