Reuben's Home Inspection Blog


Sediment Traps... Are They Really Necessary?

Sediment Trap Sediment Trap (furnace)Sediment traps might have more slang terms than any other component in a home; Drip, Drip Leg, Drip Tee, Drip Elbow, Sediment Tee, Dirt Tee, Dirt Leg, Dirt Pocket, Drip Pocket.... you get my point. These names all refer to a short length of pipe installed on the gas piping to an appliance that is designed to catch any foreign debris in the gas line, and prevent it from getting in to your fuel burning appliance and gunking things up.

The basic requirements.  Sediment trap requirements are fairly consistent across the country, but Minnesota is a little more strict.  Minnesota requires the following for a sediment trap:

  • Improperly Installed Sediment Trap Must be installed as close to the inlet of the equipment as practical
  • Must be installed ahead of all pounds-to-inches pressure regulators 
  • Must be made of a tee fitting with a capped nipple, a minimum of 3 inches in length, in the bottom opening of the run of the tee
  • Provide a 90-degree change of direction of gas flow (the photo at right is an improper installation, because it does not provide this) 
  • The cap shall be at an elevation lower than the tee fitting.   

Minnesota requires sediment traps at all automatically controlled gas utilization equipment, but good luck getting a straight definition of what "automatically controlled" is.  I've been trying for the past four years, and I've received different answers from different authorities.  Some jurisdictions say that any appliance that automatically controls the flow of gas is automatically controlled, such as a clothes dryer or a range. Other jurisdictions say that only appliances that turn on and off by themselves are automatically controlled, such as a furnace and water heater.  That's the definition I prefer to use.

How important are they?   That's debatable.  While a missing sediment trap is certainly a code violation, I don't feel that this is a serious defect.   It's just a good sign that an amateur has been doing work on the house.  I've taken apart many old sediment traps just out of curiosity, and can you guess what I've found at the bottom of every trap? Click the photo below to see.

Click the photo to see what's inside

They're becoming a thing of the past.  Natural gas is actually a very clean product today, and I've never found a trace of sediment at the bottom of any trap.    The national codes for gas piping don't require sediment traps at illuminating appliances, ranges, clothes dryers, or outdoor grills.  This leaves furnaces, boilers, and water heaters.  

But if you live in Minneapolis... you better have your sediment traps installed.  For a Minneapolis Truth-In-Sale of Housing Evaluation, any appliance that is less than three years old (from the date of the evaluation) must have a properly installed sediment trap.  If it doesn't, this requires repair with a plumbing permit.

Reuben Saltzman, Structure Tech Home Inspections - Email - Truth in Housing


Reuben Saltzman, Structure Tech Home Inspections


Comment balloon 7 commentsReuben Saltzman • August 04 2009 06:32AM


Some things hang around for a long, long time.

But, in the long run, the tee is cheaper than a new valve.

I have found sediment gunk in a couple of traps years ago but haven't taken any apart in several years.

I do write them up though.  Better I tell the client about it than have them come back and ask why I didn't.

Posted by Erby Crofutt, The Central Kentucky Home Inspector, Lexington KY (B4 U Close Home Inspections&Radon Testing ( almost 11 years ago

Erby - I make a mention of them in my reports, and I usually leave it at that.  

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 11 years ago

I've never mentioned a missing sediment trap here in California because we don't use them. I've only found one in over 10,000 home inspections, so my presumption is that the guy who installed it probably came from another state.

Posted by Not a real person almost 11 years ago

Someone somewhere had a problem at one time or he was just a guy trying to sell more copper pipe.

Posted by Gene Allen, Realty Consultant for Cary Real Estate (Fathom Realty) almost 11 years ago

Russel - and they installed it wrong!  Thanks for letting me use the photo.

Gene - I've heard that natural gas used to be a lot dirtier.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 11 years ago

A Minneapolis Home Inspector cited me for not havin a dirt trap for my gas clothes dryer. There are two dirt traps on the whole system though (one for the furnace; one for the water heater). Do I really need a third for the dryer? Seems like overkill.

Posted by Nick over 4 years ago

Yes; scroll down to 408.4

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 4 years ago