Replace underground cast iron?

I'm going to be tearing out and replacing our patio soon. There is a 4" cast iron line that runs under the patio to the septic tank that services the far end of the house. The cast iron is about 36 years old. Should I use this opportunity to replace the cast iron with PVC? We've never had any problems (back up's, etc) with this line.

If it were Orangeburg I'd say yes, but if it has been working fine and there is no visible degredation, leave sleeping dogs lie.

I would leave the cast iron line alone. I seen 100 year old cast iron sewers that are in great shape still.

How big is the patio going to be???

Since you have a septic tank the line should not be to deep...so replacement would not be to hard...you might want to run a camera down the line and see what the condition of the line is...what is the distance from the house to the tank??

Do you plan on staying in the home the rest of your life....

Thanks for the replies!

The pipe is about 2-3 feet under the surface, and runs about the entire length of the house (~50 feet). I guess they could have just as easily run it inside the house, but didn't. I'm not complaining, because it made finishing the basement much easier. The patio will cover about 15-20 feet of it.

Back in 1999, we had the electric service replaced, and the backhoe hit this line because I forgot to have it marked. We had a plumber do a PVC patch job and its still working fine. We plan on staying here the duration, so the camera idea is probably a good investment. Thanks again.