The true solution is to replace the main drain to the street. Roots can only get in a broken pipe, and they can't break a pipe. Root issues are usually only a problem with old cast iron or clay drains that have failed, and thus are also leaching contaminants into the soil. Fix the problem, not the symptom of the problem. Once the drain is replaced with PVC, you won't have problems with roots ever again.

My understanding is that roots can work their way in to seams where pipes are joined. OK, not with responsibly bonded PVC, but certainly with clay pipes that are still quite functional.

The clogs I'm worried about are actually under the house. There are large trees within a few yards of the house. So we're not talking here about digging up the yard, but rather foundation demolition or major tunneling.

So while pipe replacement is a true solution, it may not be the most appropriate one. That's what plumbers I have consulted say. They don't seem to agree, however, on drain treatment approaches for root management.

Are you going to just leave us floundering around trying to figure out what kind of lines are under your house,how old the house is, wherether there is or has been in the past foundation issues,wherether a camera has been run or if a sewer snake has pulled roots from the line? If you are looking for sound advise,it's most revelant.

No, I won't leave you floundering about that, because that wasn't my question. My question was about drain pre-treatment to discourage root invasion in an area that has somewhat of a history of it. The question was how best to do it.

When I said "the clogs I'm worried about", what I meant are the clogs that I'm worried might happen. Since I don't have any clogs right now, it seems a bit silly to run a camera or get a snake down there.

It may be that the best approach is to just go back to my plumber friends and have them explain more carefully to me what they were recommending. Thanks for your interest.

Running a camera through the pipes is very cheap insurance. And it is very far from "silly". Knowledge is power, and it will tell you what the problem is, and what the potential solutions to the problem might be. It's cheaper than a year's worth of "root treatment" that won't really work long term. Lining a clay pipe is also a possibility and you wouldn't have to dig up anything. However, if you do have to dig, it's better to do it before you get something impassable there and have sewage overflow the interior of the home.

And you probably want to get an arborist in there too to address taking down the trees that are too close to the house. Foundation work isn't any cheaper than plumbing work, that's for sure!

I had to have my plumber in to clean out my drain pipe when I moved into a new house, and tree roots were part of the problem. He gave me a product to use after he was done to keep the roots out. I want to say it was RootX, but I am not certain. He didn't know if it would help or not.

Here is a link that might be useful: RootX

Thanks. Yes about RootX. I've seen the stuff. It's an aquatic herbicide that is permitted in my city. But it sure isn't cheap. That's the attraction of salt. RootX is about a hundred times more expensive than salt per pound. Does it work a hundred times better? Maybe. If I want to remove existing roots, RootX may be the best way to go, as I gather the stuff foams up, sticks to, and dissolves the roots. If I just want to discourage future root invasion, salt is easy and almost free.

Seems to me whatever you use has to stick to the inside of the pipe(s) in order to work. After all, the entire purpose of the pipe is to move waste away from the house.

Salt solution is not going to do that.

If this is a recurring problem, I'd install a clean out capable of easily allowing a mechanical drain cleaner access and periodically using a rental machine(to minimize the cost).

My understanding is that the salt solution is a strong dessicant that is absorbed by roots, or protoroots. It certainly doesn't have to stick to the pipes, but just to whatever is trying to invade the pipes. The idea is to make the pipes less accommodating to roots, and throwing root dessicant down the pipes every month or two seems a good way to do that.

I'm talking potentially $5/year and one hand, for clean drains. What is being recommended here, with excavating, tree removal, cleanout rental, toilet removal, and repiping is a lot more money and effort. Eventually, you have to do it right, but putting that date off doesn't make it any harder once it needs to be done right.

Ask This Old House did a episode on relining a sewer line about a year ago. I understand that this would be much more expensive than the $5/year but figured I would at least point to that episode. Looks like an interesting concept if the sewer line isn't crushed.

Here is a link that might be useful: Ask This Old House relines sewer line

I was thinking the same thing too....

It's a process that involves cleaning the pipe thoroughly, then using steam pressure to insert an epoxy resin-coated sleeve the length of the pipe. As shown on the This Old House segment, it works on residences where digging up the drain pipes under the house or slab are impractical, but also for much larger pipes for municipal sewage lines. Not cheap, but then sometimes it's simply impossible to dig....

Cheers