Question 1

What is a P trap?

Accepted Answer

A P trap is a curved section of pipe fitted beneath sinks, baths or other fixtures. It holds a small amount of water, forming a water seal that blocks sewer gases and bad smells from rising back through the waste pipe. The P-trap also collects solids or debris, helping protect further downstream pipework from blockages. The outlet of the P trap connects to the building’s internal drainage or waste stack.

Question 2

What is a gully trap?

Accepted Answer

A gully trap is an outside drainage fitting that’s positioned at or just below ground level. It links surface water or wastewater outlets, such as rainwater from gutters, paved areas or greywater drains, to the underground drainage system. The gully trap keeps some water to form a barrier against odours and gases, and usually has a grate or hopper to stop larger debris entering the drain.

Question 3

What’s the difference between a bottle trap and a bottle gully trap?

Accepted Answer

A bottle trap is fitted under sinks or basins to stop odours by a water seal. It’s designed to be compact and is usually installed in spaces where there isn’t room for a p trap.

A bottle gully trap does the same job outside, connecting surface or rainwater to underground drains. Unlike bottle traps, bottle gully traps are not designed to be particularly compact. The ‘bottle’ part is a removable chamber that makes for easier cleaning and rodding.

P Traps & Gully traps

110mm Brett Martin Underground Low Trapped Gully

110mm Underground Lowback P Trap

FloPlast Underground 110mm Bottle Gully Trap

Osmadrain Single Socket Universal Gully Trap 110mm 4D500

FloPlast Push-Fit Single Socket Low Back P Trap 110mm