How often should I clean the drains in my house?
Normal modern drain installations do not require any regular cleaning. If you notice a clog/slowdown or gurgling, a targeted cleaning may help. But if your concern is buildup of material inside of drain/waste/vent pipes, this is rarely a concern. Sometimes after 50-100 years there can be enough buildup to cause a problem. But preemptive cleaning of drains is not typically worth it.