A home inspection includes the visible plumbing systems in the home. This includes the plumbing under sinks. On item we look at is the trap under the sink and make sure it is not leaking but also that it is the proper type of material and design.

A common defect noted in plumbing fixtures is the use of an S-trap. The first picture shows an image from an inspection where an S-trap was being used in a newer construction home. This is incorrect and should be corrected. An S-trap design allows for water to be siphoned out of the trap, breaking the water seal and allowing sewer gas back into the home.

The 2nd image shows the difference between an S-trap and a proper P-trap. While S-traps may have been acceptable in the past, current building knowledge and standards don’t allow them. I always recommend fixing these as methane gas leaking into your home can be both stinky and dangerous. Oftentimes an S-trap in newer homes indicated homeowner or handyman work and a qualified plumber should know the codes and requirements for proper plumbing.