I was wondering if anyone could tell me if its possible to tap into the main drain line for my house which is cast iron. I want to install french drains in the yard due to sloped yard and I was wondering if it would be a good idea to connect the french drain to the main drain for the house. My house is on a raised foundation so all the pipes are easy to get to. Thanks in advance for any inputs

That would be illegal to pipe rain runnoff into the sewer pipes in some localities. So knowing what country, state and City might let us find out if its legal or not where you are.n

Im in national city, CA

Probably illegal but check with your water department. They do not want to treat rainwater.

They may let you tie a french drain into their storm sewers if they have them, but not your sewage line. Maybe you can install a sump pit in the ground and pump/pipe the water out to the curb