Before revision: A Buchan trap (alternative names: Bristol interceptor, interceptor trap and disconnecting trap) is a device made from fireclay located in a domestic sewer pipe to prevent odours entering the pipe from the public sewer and thus the property served by the drain .
After revision: A Buchan trap (alternative names: Bristol interceptor, interceptor trap and disconnecting trap) is a device fitted in a domestic sewer pipe to prevent odours entering the pipe from the public sewer and permeating the house, a common problem before individual plumbing fittings were separately trapped .