How to Measure a P-Trap

The P-trap is a crucial piece of sink and drain plumbing because it provides a barrier between the drains and the nasty things that lurk inside, including bacteria and sewer gas odors. If the P-trap under your sink becomes cracked and damaged it requires immediate replacement. Save yourself multiple trips to the hardware store to locate the correct size P-trap by measuring the existing unit. This measurement is achieved without the need for expensive, specialized equipment.

Rubber gloves
Safety goggles
Bucket
Pipe wrench
Rag
String
Measuring tape

Instructions

- 1
  Remove all the items under your sink. Slip on a pair of rubber gloves and safety goggles to protect yourself from the potentially dangerous chemicals and bacteria lurking inside the existing trap.
- 2
  Slide a bucket under the existing trap and loosen the compression nut holding the P-trap to the sink drain pipe with a pipe wrench. Loosen the compression nut that is holding the trap to the drain pipe that leads to the wall.
- 3
  Pull the existing P-trap out and wipe down either end of the pipe with an old rag. Wrap a piece of string around the pipe only once. Remove the string and measure its length with a measuring tape. This is the number to take when purchasing a replacement pipe.

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