Ken writes:
What is the best treatment that I can use in my drains to prevent root growth? I had to replace an underground pipe earlier this year because of tree root growth.

Ken,
I can imagine how unhappy you were with the prospect of having to replace the old piping. Tree roots are a huge threat to your main. The roots go after any source of moisture and once they work into your drains, the problems only escalate.
Both you and your pocketbook know all to well what the end result is, costly digging and replacement.
You probably had a plumber send a camera down the main to ascertain the damage and extent thereof. Camera work is a plumber's best friend because we charge so much to do it. For the homeowner, it just downright "stinks". You pay the plumber a couple hundred dollars to get a videotape of the most horrifying movie you've ever experienced. No popcorn or soda because you probably wouldn't be able to keep it down. All you get is 20 minutes of confirmation that you'll be spending a whole lot more money if you want your plumbing to drain instead of fill up your basement.
What's worse for you is the fact that you only replaced a section of piping instead of the whole run from the house out to the street. I'm guessing you made the decision because you didn't have the money to replace everything.
I replaced a main that took three days to finish and charged the guy just over $8000.
I wouldn't s--t ya' man, you're my favorite turd. We're talking about pulling permits, renting a backhoe, tearing up the entire front yard, materials, and labor. The figure doesn't reflect the total damage either. When a plumber digs, we're usually not responsible for sprinkler systems or landscaping.
There are ways to retaliate regarding rambunctious roots.
The big hardware stores have some chemicals you might like. The concept for these products is to inhibit the growth of the roots. You simply dump the product into a main cleanout or even a toilet and flush them down the drain, exposing the roots to the chemicals. If you're going to do this, I have some pointers:

*Do not buy products that contain copper sulfate. It is highly poisonous and should never be introduced into our water/waste systems.
*Only buy root-killing products which are biodegradable.
*Find a product which foams once introduced to water. The foam will reach the entire internal surface of your pipes.
*Introduce the chemical at night after everyone has "taken care of business" and is in bed. This will help to ensure the solution isn't washed away without giving it a chance to work.
*FOLLOW THE DIRECTIONS. I'm not kidding! Use gloves and safety glasses. Most products will dissuade roots for an entire year, so don't even think about doing it twice a month.

The last thing I can suggest is rock salt. My father would offer this suggestion to customers all the time when I was a kid and I've never heard anyone say it was bad advice. I also called Jefferson County Utilities and their only objection was the introduction of products containing the aforementioned copper sulfate.
You take one gallon of rock salt, the same stuff you use to de-ice your sidewalk, and mix it in a five gallon bucket filled with hot water. Stir the contents until the salt has dissolved. Once again, wait until the end of the night and pour the mixture down the drain. I'd do this twice to four times a year depending on how active the roots are.
I would not recommend using salt if you have a septic system. Worse problems can occur as a septic system works off entirely different principals than a main line that connects to the city's sewer.

One other thing, roots not only creep in to your pipes through small openings, they can break pipes apart, destroying the integrity of the pipe. When this happens, no amount of chemical is going to fix the problem. You're going to need to replace the line.
New applications have come out in the past few years, which involve coating the inside of the pipe with a liner. This is somewhat similar to coating the truck of a bed with a spray-on liner. I have also heard about a system where a polyethylene (PE) pipe can be fed through the inside of your pipe. I can't speak with any authority on the system but common sense tells me it would decrease the ID (inner diameter). I don't know if I like that notion. I will do some homework on it though and let you know.
The best advice is to have the entire line removed and upgraded to modern piping. Do the best with what you have. I realize we all have to live within our means.
I do have one last recommendation for those of you who may purchase a home in the future. If the home isn't relatively new, pay a plumber to stick a camera down the drain.
You can also have him (me) look at the rest of the plumbing in the house. The money you spend may save you thousands in the future. If you think a home inspector is going to do the same job then ask him if he has a plumbing license. My home inspector came highly recommended but didn't know squat about "real" plumbing issues.

I do appreciate any comments a reader may have and you can always email me directly by clicking "send me a message" located in the contributor information box at the top right of this page.
I'll be the last guy to tell you I know "everything" about plumbing so if I missed anything or sparked some imagination, please let me know.

If you've tried everything and just want an honest plumber with insurance and a license, I've heard great things about 5150 plumbing. Go up to the "search your hub" box and type in 5150 Plumbing.

Later,
Dr. Plumb