Replace lead bend tub drain pipe?

[Seth]

I am remodeling an old bathroom (in a 100 yr. old house; not sure of the age of the plumbing in question). The tub is a corner tub, made of cast iron. I plan to keep it. I have pulled up the flooring all around the tub. The drain pipe from the tub is a lead bend. From the bathtub drain it initially runs sideways, perpendicular to the long dimension of the tub, at the front (faucet end) of the tub. Before reaching the side of the tub, there is a joint, where one piece of lead pipe connects to another. This second piece of lead piping then daylights from under the side of the tub. At that point it bends and heads parallel to the long dimension of the tub, perhaps a foot away from the side of the tub. (Because the joists are perpendicular to the long dimension of the tub, they are notched to permit the drain piping space to pass through them). About halfway or 2/3 of the way toward the back of the tub, the piping bends again and runs at an angle, heading back under the tub, where it eventually connects to a 4" cast iron waste pipe. The connection point between the lead bend and the cast iron waste pipe is underneath the back corner of the tub, closest to the wall. This connection point is barely visible, and it is not accessible without pulling the tub up and moving it away from the place where it sits. A 4" cast iron vent pipe (stack) is located in the wall at the same back corner of the tub.

My plumber initially told me that I while I have the floor up and open, I should have him replace lead drain piping with PVC pipe. He is now backing off, suggesting that he replace only that section of the lead bend beginning at the tub drain and ending where the lead bend is exposed (daylights) along the side of the tub. I think that he is concerned about the weight and difficulty of moving the tub. My concern is that we have had some modest, seemingly ongoing leakage from this bathroom, affecting the plaster ceiling below, and don't know the source. It seems to me that the source could be the connection point between the lead bend and the 4" cast iron pipe, although I have no specific reason to suspect that. (I rather suspect the toilet and/or shower water repeatedly escaping the shower curtain). But even if there is no leak at the lead bend/CI junction now, my question is: should I be concerned about how long this connection point will remain intact? Certainly I will not be happy if I have to rip out a new tile floor and tile tub surround to get at it, should there be a problem sometime after the room is finished.

Your thoughts on this would be much appreciated. Seth.

[jadnashua]

Is there a trap anywhere in that scheme for the tub? Lead is pretty inert, so if it doesn't get flexed, or you didn't try to run a snake down it, it could last for eons. I assume that if you did need to gain access, you'd have to tear up the ceilings below?

Is there any evidence of water spotting or rot near the shower or the toilet? If you find that, then you've probably isolated the leak. Both the shower and toilet are more likely to be the culprits than the drain itself. For tiling info, highly suggest you check out www.johnbridge.com.

[Seth]

Thanks for the reply, Jim. I believe there is a trap at the drain end of the tub. There is some evidence of water damage/rot at the side of the tub where the shower curtain meets (or is supposed to meet) the end, tiled wall, and some water damage/rot around the toilet. So, I do suspect one or both of those areas as being the likely culprits in regards to the ceiling damage below.

I guess the stand-alone question is: Is there a problem with pulling the tub out of the way, other than the physical difficulty of moving such a large, heavy object?

Thanks again, Seth.

[jadnashua]

If you are going to try to save the tub, moving it has some risk. It is very heavy. Other than that, yes, you could remove it, replace the drains, then reinstall.