A waste trap 10 for use in plumbing installations is provided, the trap comprising a unitary metal body 12 defining an interior volume, and having a tubular plastics insert 20 located in an inlet 14 of the body 12 and extending into the volume to below the height of a waste outlet 16. The insert 20 partitions the upper portion of the volume into two regions, and serves to provide a water seal between the inlet 14 and the outlet 16 when the trap is in use. The insert is non-removably secured to the body.