? pouring salt water down cast iron sewer, Bad?

[Emster]

I have an older house with cast iron sewer and I want to set up a water change system that ties into my sewer line. Should I do this? What do you guys do with your old salt water?

[sprinj76]

Is the drain used a lot? If all you are going to be dumping down the drain is the salt water then I would be worried about rust eating away slowly at the pipes. If it is medium to heavly used I wouldn't be too worried, not enough contact time to cause issues.

I personally dump mine out side in a gravel turn around that we don't want plants to live in any ways.

[Emster]

Yes it is in a drain that I use every day. I work for a general contractor and asked the plumber that we use if I can do this and he said he would not recommend it, although I have poured a little here and there for the last four years and did not think about it. Most of my water change water is pour out in the street. I'm going to be setting up a frag tank and want to plumb it to the drain so all I would have to do is turn a valve and the old salt water would be pumped out but don't want to rust out my sewer and then have to pay a plumber big money to replace it. Plumbers are not cheap :( Should I go for it?

[H20ENG]

If you pour it down the toilet, then flush the toilet, it will all be washed away with fresh water. Its only an issue if the drain does not get flushed out after the salt.

Cast iron is very tough, dont worry.

[rick rottet]

saltwater wont hurt the pipes any more than some of the caustic cleaning products out there... drain cleaners (lye), for one example, tub and toilet cleaners for another. i was a plumber for almost 3 years, cast iron pipes are pretty thick, it would take several decades of saltwater exposure to rust through them. in fact, it isnt so much the exposure to saltwater, but when the water evaporates, the salt itself stays behind and enhances the oxidation process. oxygen is what rusts metals. as mentioned, as long as the drain is frequently flushed, or at least flushed after the saltwater goes into it... not much to worry about.
i wouldnt hesitate to go for it.