Sediment Trap (Drip Leg) | Explained

Sediment traps are designed to prevent most particles from entering open gas lines, which would cause clogs or other issues with operation.

They also help remove any excess moisture that could lead to liquid buildup while preventing hazardous gases such as methane leaks during periods of heavy rainfall or flooding events.

This blog post will discuss where to install sediment traps on your property and how they work.

How does a sediment trap installed on the gas line work?

The sediment trap or a drip leg is installed downstream of any elevations where solid particles may accumulate. The solids are captured in the sediment trap while gas continues to flow without interruption.

The collected material can then be periodically removed from the sediment trap for disposal or recycling.

Sediment traps work with liquids and gases, but they’re commonly used as an upstream component on oil pipelines that carry products such as gasoline and natural gas – which could have dust, dirt, or other particulates mixed in them if not filtered out.

Sediment Trap in Plumbing code

Where a sediment trap is not incorporated as a part of the appliance, a sediment trap shall be installed downstream of the appliance shutoff valve as close to the inlet of the appliance as practical, before the flex connector, where used at the time of appliance installation.

The sediment trap shall be either a tee fitting with a capped nipple in the bottom outlet, as illustrated or other device recognized as an effective sediment trap.

Illuminating appliances, ranges, clothes dryers, decorative appliances for installation in vented fireplaces, gas fireplaces, and outdoor grills shall not be required to be so equipped. [NFPA 54:9.6.8) (UPC 1212.9).(CPC 1212.9).

Code Reference: Uniform Plumbing – California Plumbing Code.
sediment trap, gas line sediment trap,
drip leg

What’s wrong with using a simple filter? (For example, paper filters)

Are you wondering why you should not go for a simple filter if the main purpose of a sediment trap is to prevent particles into your gas line? Well, with a paper filter, you would need to replace it every few days.

Sediment traps can be left in place for as long as they’re needed – and depending on the application. This could last anywhere from months to years. Therefore, installing a sediment trap is more cost-effective than using a paper filter.

Benefits of installing a gas line sediment trap

Some of the benefits of installing a gas line sediment trap include:

  1. It prevents filter clogging and saves money by ensuring that the gas is pure and free of particulates
  2. It provides an added safety measure against gas leaks or fire hazards from pressure buildup within the pipeline system.
  3. Sediment accumulation prevents gas flow throughout the trap, meaning you can leave it in place for as long as needed – and depending on your application, that could last anywhere from months to years. This means less maintenance costs overall.
  4. The best part is that sediment traps are an affordable solution for protecting pipelines without having to dig up expensive underground piping systems at all.

Gas Line sediment trap maintenance

Maintenance of the gas line sediment trap is easy. The trap needs to be flushed clean every few weeks by removing the sediment from inside.

Sediment buildup is inevitable, but a good regular cleaning schedule will fend off excessive accumulation and keep your gas line running smoothly.

The installation process for the gas line sediment trap:

  • Cut the gas line so it is below where the sediment trap will be installed.
  • Install a new coupling on one end of each section and flare to fit securely with an adjustable wrench or by tapping them together with a brass hammer.
  • Apply pipe dope for corrosion protection if desired.
  • Thread the two sections back together using wrenches inserted in opposite ends of both pieces (one hand inside, one outside) and tighten until they are snug together but not tight enough to crush seals or blow out gaskets. Some manufacturers recommend applying pipe sealant such as Teflon tape at this time; others do not advise doing that unless there has been leakage past threaded connections in previous installations. If you use a sealant, don’t over-tighten the connections.
  • Run a clean rag around all exposed metal surfaces that make contact before applying Teflon tape for added protection against corrosion if desired; thoroughly wipe off any excess grease or oil. Allow time for the sealing compound to dry before turning the gas back on.


It’s essential to plan for when things go wrong; this includes measures to prevent gas leaks or fires due to pressure buildup within the pipeline system. Luckily, the installation of sediment traps on your gas line makes these risks very low.

Sediment traps are a great way to keep your gas line free of dirt and other particles that can clog up or create expensive damage to your pipes.

In addition, sediment traps catch any corrosion that comes from the inside of your gas pipes. This helps protect your appliances from corrosion damage that could result in expensive repairs or replacements over time.