Which installation requires a deep seal trap?

A deep seal trap is specifically designed to provide a sufficient water seal while also accommodating situations where venting is not feasible. In plumbing systems, traps are used to prevent sewer gases from entering living spaces, and they do this by maintaining a water barrier.

When a trap cannot be vented, the risk increases for siphoning due to negative pressure caused by water flow, which can lead to the loss of the water seal and, consequently, the reentry of unpleasant odors and gases into the building. A deep seal trap helps mitigate this issue by maintaining a larger volume of water in the trap itself, which can better withstand the fluctuations in pressure without losing its seal.

Other installations, such as washing machines, kitchen sinks, and bathroom sinks, generally have access to proper venting, which assists in the drainage and pressure equilibrium, reducing the need for a deep seal trap. In situations where adequate venting cannot be provided, however, the deep seal trap becomes a reliable solution for maintaining a secure barrier against sewer gases.