Cast iron soil pipe join leaking

[Fettled]

Grateful for any suggestions on fixing this leak in the join between two sections of cast iron soil pipe. I've read about hemp and tar and molten lead on this forum but more inclined for go for putty if folk think that'll do the job. There's a photo of the offending item attached. I hope.

 

[Bosswhite]

Clean out joints and renew with Plumbers Putty.
You could put a bead of silicon around the down joints before you use the Plumbers Putty ( Belt and Braces)

 

[Fettled]

Thanks Bosswhite, all sounds eminently sensible and do-able.

 

[Agile]

Are you sure that the drain is not blocked and slow draining?

Tony

 

[Fettled]

Hmmmm. Tony that is a fine point. How the heck to check though? It's a down pipe at the back of the terraced house, which at ground level routes under the sub basement floor and out to the street/main sewer. Richard

 

[Hugh Jaleak]

When the toilets are flushed, does the level in the pan seem to rise normally or does rise right up and then subside slowly? Latter would indicate a possible blockage.

 

[Agile]

Because those joints are all "pushed in from above" there is no inclination to leak like that if the pipe is open to the flow which at that height it normally would be!

Tony

 

[Fettled]

Hugh, there's no sign of any blockage from two floors higher up where the bathroom waste to that stack originates. That doesn't however rule out a slow drain away situation and as Tony says there a clue here! The power of all this combined wisdom is great! How though to get this checked out properly though? Whacking putty in the cracks may just be obscuring a problem. There is a manhole, albeit cemented shut, in a stone tiled floor in the basement not far from where this stack comes down. I suppose this stack could somehow be blasted upwards from that point. There's a breather "chimney" at the top of the stack which is a precarious high rooftop place. Or perhaps break into the stack somehow near to ground level. I'm guessing here but my money's on the manhole option in the basement as being voted number one way of checking this. Views guys?

 

[AL66]

At the bottom of your photo there appears to be the edge of a removable access door on the tee below. You could try opening it - might not be very pleasant though if it is blocked.

 

[Nige F]

I personally would go for the manhole in the cellar because it needs to be accesible anyway if there is no problem now there could be in the future. I don't trust those little access doors - if the bolts snap you cant get it to seal again and it will leak forever Your call.

 

[Fettled]

Manhole I think. The access door is a good spot but it just might be v messy!

 

[Bosswhite]

Once the old putty has been removed and one gets to see the joint between the down pipe and collar, running water through the toilet or upstairs bath would show up in the collar joint, I would have thought.
The problem could be an old blockage in the past thats cleared up, I would have thought if its a blockage in the Branch everytime the bath is drained water would run down the outside of the soil pipe, being an indication that the branch is blocked.
Again I would have thought it would also show up in the toilet pan as Hugh Leak suggests

 

[Fettled]

Another brilliant suggestion and thanks Bosswhite. I'll dig it out and flush like a madman.... Watch this space.

 

[Fettled]

Just for the sake of completeness here's the outcome, so far at least. I raised the manhole outside the street side of the house and observed the speed and volume of water passing out of the drain. It swooshed out immediately and with gusto from which I concluded no blockage. The leak was caused, I believe by the plastic downpipe not being properly fitted to the cast iron downpipe. You can see if you look carefully at the pic that the upper part is plastic and the lower past cast. I gouged out all I could and sealed with bitumen drain sealant. Fingers crossed now. Will repaint soon so I'll be able to see if it's worked. Messy stuff that bitumen sealant. Maybe should have used cement.