Lead + Copper = Corrosion ?

[Moggs]

I posted this earlier , but it seems to have not appeared.

This is about a problem of my neighbour's. I am preparing her for a discussion with plumber/installer of her bath room which was fitted about 4 months ago.

These are 1909 large semis, the bath room is sited above the entrance hall. Cold water is diverted up to the bath room via a lead pipe ( this is original of course ) which is partly buried in the plaster of an internal corner of the hall against two external walls.

My neighbour has just noticed damp in the hall in this corner. I have examined and it is clear that the lead pipe is failing.

My first reaction was that either the pipe has failed with age ( presumbably they do eventually ? ) or that , considering the coincidence of the recent bath room work , the joing work above has disturbed /shaken the lead pipe and caused the failure. However , to be honest the partial burying of the pipe in the wall appears to make it very stable I am assuming ( but cannot be sure ) that the installer connected copper to the lead somewhere after it entered the bath room above. Alternatively I suppose it could be joined to plastic , (but can you physically join lead to plastic ? )

However I have now remembered, I think, that copper joined to lead causes corrosion ( to the lead I suppose). So that Is now my prime suspicion for cause of the failure at this time.

I would appreciate any views / comments on my analysis.

If it is relevant , this is a hard water area. ( Very hard I would say ).

When I did the equivalent bathroom refurb on my own house I made the offending lead pipe redundant ,bypassing it with surface copper and leaving the lead in situ. At the time i was not think ingof , or motivated by, corrosion issues but by

1.the desire to avoid the problem of an stuck broken stopcock in the lead run.

1. getting rid of lead in system with a view to a possible future water softener. I knew that lead is a no no in systems with a softener. Possibly because of similar , chemical reaction issues ?

Thanks for any thoughts

Richard

[Dave Plowman (News)]

The incoming main to here is lead. When I moved in some 30 odd years ago I wiped in some copper to it initially to fit a new stopcock as the old was leaking - and to be able to install all new copper in the house afterwards, which I did. That original joint is still there and fine.

[Phil L]

this is the norm for buildings of that age

water is tracking back from a leak further up I would say

Not really no, lead water pipes will happily continue to function normally fror hundreds of years

It's where he's joined copper to the lead, or maybe where he's joined copper to copper and it's running along the outside of the pipe until it gets to the plaster in the hall.

Considering it's been in place for 4 months, the leak is probably tiny - no more than a few drops per day, but over a few months that probably equates to a few pints

It doesn't cause corrosion, and even if it did, it wouldn't become apparent after just 4 months.

Just get the plumber back and tell him there's obviously a leak - he'll probably find it and repair it in less than an hour

[Bob Eager]

I did the same except I used a coupling - also 30 years (and a few months) ago. We've moved since, but the only house is only 50 yards away and I know the new owner; I'm sure I'd have heard of any problems.

[js.b1]

No, you have a leak.

There are lead-loks,

a somewhat peculiarly media-marketing tarted up website compared to the old one. Looks like someone found a script and made the business layout fit it rather than the layout fit the business!

Lead however does NOT like being physically abused like a piece of flexible conduit for example and can decide to pee all over the place if you try it. Lead water pipes are much thicker wall than gas pipes, but that can be their undoing if someone is clueless. So I would check a stopcock is functioning properly, always worth adding 1/4-turn T-top pegler valves to bath, sink, toilet including the hot. Just turn them every year, the cheap screwdriver stuff are a waste of space.

[Moggs]

Thanks for your comments. You mostly seem to be discounting my notion that corrosion caused by marrying lead and copper could be the cause & I take note of that.

I would say the leak is definitly not in the bathroom . I did not mention in my original post , but the upper part of hall around the lead pipe is not damp. In the ceiling area of the hall around the pipe it is clean and dry. There is is a clear contrast with the damp area lower down. The area around the stop c*ck is not particularly wet. Else where on the vertical pipe is an area where you can get part of a small finger parlty behid the pipe , it is wet , not just damp. Around there is also dark material that I would describe as corrosion. I would say "rust" but i guess that is not appropriate for lead. Before you say it , it is lead not iron . I have seen it taken out of other neibouring houses & its definitly led.

Thanks again

Richard

[js.b1]

Lead can corrode due to salts in brickwork, and rust can be caused by disintegrating crampets which are a "hammer in nail clip" for lead pipes.

You can get condensate migrating through a wall to condense on a cold surface (pipe) which tracks down. However I would examine the pipe carefully. Might be worth checking to see if there is any spare wallpaper - or alternative route for the pipe (even surface or boxed in).

[NT]

Lead pipes become lined with scale, which minimises leaching of lead into drinking water. With a water softener this scaling doesnt happen, and lead leaching levels are many times higher.

Personally I'd just get rid of the lead pipe, this is one example of old technology youre better off without.

NT

[grimly4]

It might be condensation on the new copper section, running down the lead length into the plaster.