Is it safe to search for someone to repair the sewer pipe at home on a website like 58 City?

Maybe it's safe. You can ask him to bring a certificate (that is, a plumber's qualification certificate).

If you are not at ease, you can also go to the major decoration building materials markets to see their faces. If you feel at ease, you can let them come.

There are also small shops selling hardware and building materials near the community, which generally provide installation and maintenance services and charge a little service fee.