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Sediment Trap

A sediment trap is a short piece of gas pipe installed near an appliance that helps to collect debris in the gas line.  The idea is that any debris in the gas line will collect in the sediment trap before that debris can foul up the appliance’s gas valve and cause trouble.

The sediment trap on my water heater is nice and long.

You’ll often hear the term “drip leg” instead of sediment trap.  In fact that’s what I usually call it, but it’s not really the same thing.

A sediment trap is just a T fitting in the gas pipe with a capped pipe nipple at the bottom of the T.  It’s required at a furnace, boiler, and water heater, but not at a clothes dryer, a kitchen range, or a fireplace.

The sediment trap needs to be installed downstream of the appliance’s shutoff valve and as close to the appliance as practical.  And it needs to be installed so that the gas flow changes direction, so that the debris will fall into the trap.  If you install it so that the gas flows horizontally then the debris might just jump over the trap and get into the gas valve.

There’s no excuse for the lack of a sediment trap.  A competent plumber knows it’s required by all relevant codes and by the appliance manufacturer’s instructions.  And you don’t want an incompetent plumber installing your gas pipes.  So if it’s missing that’s one small strike against the plumbing system as we work on telling the story of the house.

But how bad is this problem, really?  Well, I’ve heard that this might have been an issue many years ago, but today the natural gas delivered to your house generally is clean and dry.  And I’ve never personally heard of a problem that occurred because of a missing sediment trap.

So have a sediment trap installed the next time the appliance is replaced.  In the meantime it’ll just be one of the many things in your house that’s not perfect.

Galvanized pipes

Galvanized steel pipes were used for potable water distribution in single family homes as well as in apartment and condominium buildings until about the 1960’s.  It was the standard water pipe material; everybody used it pretty much exclusively.  They’re joined together with threaded fittings.

Galvanized steel pipes are just steel with a zinc coating for protection.  The zinc coating is the “galvanized” part.  But over time the zinc coating wears away, and you’re down to bare steel.  And of course steel rusts.


The inside of this galvanized steel water pipe is corroded.

The pipes will rust on the inside (obviously, since that’s where the water is), and this corrosion tends to clog and choke down the inside diameter of the pipe.  With the smaller inside diameter you’ll get less water flow and lower pressure at your fixtures.  Hot water pipes tend to corrode more quickly, because the heat accelerates the corrosion process.


Reduced water flow and pressure is the predominant problem, but the pipes can also rust through and start to leak.  And of course leaking water pipes can cause a tremendous amount of damage, especially if the leak is inside a wall.  The threads typically rust first, so this is where you want to start looking if you’re going to examine your galvanized pipes.


This pipe rusted all the way through and had to be repaired with a clamp.









The life expectancy of galvanized pipes varies – a lot.  I’ve seen galvanized steel water pipes in houses from the 1920’s and even the 1910’s that are in surprisingly good condition.  The water flow through these pipes is good, and there’s little sign of rusting.  Folks knew how to make pipes back then.  Still, these pipes are very old, certainly have some rust, and are probably near the end of their expected life.  And I’ve seen galvanized pipes from this era that are badly rusted and provide terrible pressure.  You should plan on needing to replace all galvanized pipes in the near future.  Also, most houses of this vintage have had all (or almost all) of their galvanized pipes replaced already.  So if your house still has galvanized pipes then it’s behind the curve in terms of being updated like it needs to be – something to keep in mind when making an offer.


This pipe fitting is rusted through and leaking, just a little bit. The leak will just get worse and worse, until . . . disaster.


On the other hand, some Chicago buildings from the 1950’s and 1960’s have already had to replace their galvanized pipes.  It seems that cheaper production methods and materials created an inferior product that quickly deteriorated.  And I’ve seen pretty much everything between these two extremes.  Either way, if you have galvanized steel water pipes in your house it’s probably near the end of its expected lifespan, and you should plan on needing to replace it in the near future.

Keep in mind that there’s no way to know for sure when galvanized pipes will fail.  You can have a team of scientists and engineers inside your house for a month, and you still can’t know.  You just have to follow the basic guidelines.

In Chicagoland, almost all jurisdictions require new water pipes to be copper.  But some cities will allow PEX (cross linked polyethylene) water pipes.  PEX is used almost exclusively throughout much of the rest of the country, so it has a long record of success, and the problems with fittings (the weak link in any water system) have been worked out by others.