P-trap constantly running

PlumbingUpdated March 2026

The answer to 'P-trap constantly running' is that a continuously running p-trap is usually caused by a clogged or blocked drain. The p-trap is the curved pipe under your sink that is designed to hold a small amount of water, creating a seal that prevents sewer gases from entering your home. If the drain is blocked, the water in the p-trap will continuously run down the drain, causing the issue.

Some common causes of a blocked drain include hair, food debris, soap scum buildup, or a foreign object stuck in the drain. You can try to resolve this issue yourself by using a plunger or drain snake to clear the blockage. However, if the problem persists or you are unable to clear the clog, it's best to call a professional plumber to diagnose and fix the issue.

Sources

International Association of Plumbing and Mechanical Officials— authority

Plumbing Manufacturers International— authority

This Old House: How to Unclog a Sink Drain— guide

Step-by-Step Guide

1
Use a plunger
Try plunging the drain to dislodge any blockages. Fill the sink about 1/3 full with water, then plunge up and down vigorously for 15-20 seconds.
2
Use a drain snake
If plunging doesn't work, use a drain snake or auger to physically break up the clog. Carefully feed the snake into the drain and turn the handle to extend the cable and reach the blockage.

Frequently Asked Questions

How do I know if my p-trap is clogged?

Signs of a clogged p-trap include slow draining water, gurgling sounds, or a constantly running p-trap.

Can I use chemical drain cleaners to fix a clogged p-trap?

Chemical drain cleaners can be effective for minor clogs, but they should be used with caution. Repeated use or using too much can damage pipes over time. It's best to try a plunger or drain snake first before resorting to chemicals.

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