Q. I have had a case of plumbing brought to my notice, where the pipe from a sink stopped up between the trap and the soil-pipe. How long it had been so no one seemed to know, as the water that should have passed down the waste-pipe passed over through the vent-pipe, and found its way into the soil-pipe through the vent-drip. What is the usual way in your city to prevent this?

A. When the vent and soil pipes are carried in a recess back or near the sink, introduce your Y-branch into the vertical line of vent-pipe, half-way between the bottom and the upper edge of the sink, or other fixture. This will cause the water to show in the sink should the waste-pipe be stopped beyond the trap, but will not allow the sink to run over.

If the pipes are all below the floor, arch the vent-pipe up behind the sink sufficiently high to raise water into the bottom of the sink, but not high enough to run over.