How do I choose a material for sewage piping in a private house?

Plastic pipes dominate the market these days, and there's a reason for it! Polypropylene and PVC are cheaper, don't rust, and are easier to install - you can handle it even without special experience. The main thing is to pick pipes with the right diameter: for in-house plumbing you typically use 50 mm, for toilet outlets - 100 mm. PVC is more brittle, but it handles aggressive environments better, while polypropylene is stronger but can deform at high temperatures. For underground sections, corrugated polyethylene pipes are especially good - they're flexible, don't mind ground shifts and tree roots.

Cast iron pipes show up in old houses, and they're reliable, but they're a pain to deal with! Heavy, require special skills to install, rust inside over time, and get clogged. If they're already there - leave them alone. If you're doing a new system - don't bother with them. Asbestos cement is also better to avoid, even though it's durable, because the material isn't great for your health.

Here's what I'd recommend: for in-house plumbing, go with quality polypropylene with thick walls, check the marking - it should say it's for sewage. For the house entrance and underground sections, use corrugated pipe or PVC depending on soil conditions. And definitely lay all pipes with at least a 2 centimeter per meter slope - without that you'll have problems with clogs and smell!