How to Test Plumbing With Peppermint Oil

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Things You'll Need

  • 2 oz. peppermint oil

  • Bucket

  • 10 quarts hot water

  • Vent pipe cap or cover

  • Helper with good sense of smell


Look for peppermint oil at natural food stores and pharmacies.

Check your local building codes before relying on the peppermint oil test. Some require you to use an alternate method to check the air-tightness of DWV piping.

If you can smell peppermint but can't locate the leak, consider a smoke test.


Use extreme caution when working on the roof. Never climb onto the roof when it's wet or when wet leaves and debris are present. Wear an appropriate safety harness to prevent falls and injury.

You'll need peppermint oil, water, some hardware and a partner's sniffer.
Image Credit: RusN/iStock/Getty Images

A leaky vent pipe allows stinky sewer gases into the home and can even lead to an explosion caused by the methane in these gases. While leaks in a plumbing pipe are often easy to spot due to the presence of water, detecting a leak in drain, waste and vent piping can be trickier because these pipes vent only gas. Pungent peppermint oil serves a simple means of ensuring that newly installed DWV pipes are air-tight and of spotting leaks in existing systems.


Step 1

Ensure that all plumbing fixtures are set and connected, and that all traps are filled with water. Close all doors and windows to the home.

Step 2

Access the drain-waste-vent pipe on your roof. Pour 2 ounces of peppermint oil into the pipe, followed by 10 quarts of hot water. Cap the vent pipe.

Step 3

Remain outside for the duration of the peppermint oil test once you've poured the oil and water into the vent. The person who pours the peppermint carries the smell on his hands or clothes and won't be able to properly detect the smell if it manifests inside the home.


Step 4

Send a friend or family member inside the home. Instruct him to seek out the scent of peppermint and make a note of any location where he notices this distinct odor. Have the helper check around pipe joints and connectors, plumbing fixtures and traps, and all fixtures, including toilets, sinks, tubs and basement drains.

Step 5

Inspect and repair or seal all components where your test partner noticed the smell of peppermint. These spots could be allowing sewer gas to leak into your home.



Emily Beach

Emily Beach works in the commercial construction industry in Maryland. She received her LEED accreditation from the U.S. Green Building Council in 2008 and is in the process of working towards an Architectural Hardware Consultant certification from the Door and Hardware Institute. She received a bachelor's degree in economics and management from Goucher College in Towson, Maryland.