The first picture is my kitchen sink P trap. Second is bathroom sink trap.
I have some questions. 先多謝大家賜教.
1. What are those traps made of?
2. Are they better than the PVC/plastic ones?
3. Are these pipes safe for liquid plumber gel?
4. What is a good way to prevent backflow? My kitchen sink had a backflow several times in the same day, but obviously my drain does not seem to have any problem. Two handymen told me that if my neighbors have problems with their drain, then my sink can be affected. The only solution is for the building to hire a plumber to check which neighbor has that problem.
Thank you so much for any input.