Somethings you know without them being said. In this case, we are looking at the ‘handiwork’ of a not so ‘handyman’, all 4 examples are in the same house. I thought this would be a good example of what we find.
“Water filling the downstream vertical portion of the S trap will cause siphoning & loss of trap seals. Trap seals must be maintained to prevent sewer gases & vermin from entering the dwelling.”
“Accordion drains” are not allowed they are not a listed plumbing part. All legal plumbing parts in code books and are “listed”, and they must have smooth interiors. The accordion drains do not this makes them an illegal install
The slope of the trap arm or fixture drain is very important if the slope is too steep the water will be siphoned out of the trap and allow sewer gas back into the home. In this example, the fixture drain is too high and then slopes down with an accordion drain sealed with duct tape, this one’s all wrong.
In the next example, we are looking under the kitchen sink. There is an accordion drain and the trap arm discharges into a non vented drain. This will cause siphoning of the P-trap. There is a dishwasher discharge that doesn’t have a vacuum breaker on it. There’s is a second drain in the background that’s disconnected, if left uncapped it could also allow sewer gas into the home.
In the last example, we have a couple more interesting mistakes. Yes, we have the accordion drain and an improper unvented drain for the trap arm.
The water shut off valves have been set below the floor of the sink base cabinet making them nearly impossible to shut off. This install required duplicate water appliance connectors, this is not allowed. You are not supposed to connect two appliance supply lines together (water or gas). Since the valves were too low, they added another connector to reach it.
I bet you can tell this guy was not a plumber (or a finish carpenter)!!