Niccolo
Member
I'm still curious what others think of your sediment trap layout. Logically, it seems to me more likely to effectively trap sediment than the standard design, but I have no professional expertise on this topic whatsoever.
Relocate sediment trap BEFORE flex gas line
- Thread starter DIYER39
- Start date
I'm still curious what others think of your sediment trap layout. Logically, it seems to me more likely to effectively trap sediment than the standard design, but I have no professional expertise on this topic whatsoever.
Phog
Active Member
I have only ever seen them with the gas coming in from the top; in DIYER39's picture the inlet is from the side, which I have not seen. However (in my completely nonprofessional opinion) I also can't see why this wouldn't work just as well. Either way, the way I've heard it told, sediment traps are something that was more relevant back in older times when illuminating gas or town gas still had humidity and moisture in it. The moisture would collect into droplets, make the inside of your pipes flake rust off, and the drops/flakes could get into orifices etc. These days the gas is all made completely dry before it goes into the pipes so drip legs / sediment traps aren't needed anymore. But the custom of having them was written into code many years ago & remains there. It makes sense to me, but I'm not a professional. Maybe one of the pros here can confirm this story?
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DIYER39
Member
I think the code diagram is a little funky. If I were to follow it perfectly, I guess I could use an elbow and flow gas into the top and out of the side to the water heater. Have not seen it done that way before.
I think this is kind of a grey area for plumbers and from what I've read, most inspectors just want to make sure the homeowner didn't create a bomb. But what do I know. Can any pros comment?
Niccolo
Member
It's interesting that standard practice is *never* to empty sediment traps during the life of a water heater or other appliance, the implication being that very little is expected to build up in them. That makes me think they're more to catch some random debris that ends up in the pipes, say from pipe fitting, than ongoing debris from either dirty gas or flaking pipes, which would build up over time.
And yes, one shouldn't be encouraging a homeowner to empty a sediment trap, because of risks associated with reestablishing a gas seal. But it could be standard advice to have a professional empty them every X years, just like it's standard advice to check the water heater sacrificial anode and replace it if it's more than 50 percent deteriorated (and yes, I'm aware that advice is rarely actually followed, and lots of water heaters are installed in a way where the anode can't be removed/replaced without uninstalling the heater, because there isn't enough space above them).
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DIYER39
Member
This morning I spoke with a very nice gentleman from the IAPMO and I wanted to pass along some information. He is an expert in the field and is also very familiar with southern California. He was very helpful and willing to explain everything in detail, but Ill try to sum things up below. Basically, he stated:
Sediment traps do in fact have to be placed before the flex line now.
There are a few different ways to use the Tee fitting that are indeed acceptable and comply with code.
Gas coming in vertically to the top of the Tee fitting would technically be more effective, but not necessarily the only way to do it.
He pointed out that southern California does not have much sediment at all and cleaning would not be necessary
I was more curious as to why this information is not practiced or known by many people online. Some of my conversation is probably best kept private, but he did explain the wide range of contractors and companies that install water heaters who are not actual plumbers.
Sediment traps do in fact have to be placed before the flex line now.
There are a few different ways to use the Tee fitting that are indeed acceptable and comply with code.
Gas coming in vertically to the top of the Tee fitting would technically be more effective, but not necessarily the only way to do it.
He pointed out that southern California does not have much sediment at all and cleaning would not be necessary
I was more curious as to why this information is not practiced or known by many people online. Some of my conversation is probably best kept private, but he did explain the wide range of contractors and companies that install water heaters who are not actual plumbers.
Kreemoweet
In the Trades
None of it makes any sense. Sediment traps that are incorporated into the appliance obviously will be "after " the
flex line. And what about that long list of exempted appliances? How is it they do not need traps, but water
heaters do? The only "sediment" I've ever seen in a gas line is the flaking cheap black paint from the
"black iron pipe" that Lowe's sells.
flex line. And what about that long list of exempted appliances? How is it they do not need traps, but water
heaters do? The only "sediment" I've ever seen in a gas line is the flaking cheap black paint from the
"black iron pipe" that Lowe's sells.
Master Plumber Mark
Sensitivity trainer and plumber of mens souls
It really does not matter ..... I would prefer the sediment trap to be located at the control valve but
I have seen them in many places ..... A sediment trap is basically something they did a long time ago when
the gas had a lot of impurities in it....
I have seen them in many places ..... A sediment trap is basically something they did a long time ago when
the gas had a lot of impurities in it....
auberon
New Member
Bumping this because in 2026 this is still one of the top search results for where the sediment trap should be.
I was scratching my head reading the California Plumbing Code trying to figure out where it has the requirement that the sediment trap be before the flex connector. After going back and looking at older versions of the CPC, this was in the 2016 and 2019 versions, but removed in the 2022 and 2025 versions.
Here's what the 2025 CPC states:
I agree with others that in reality it doesn't really matter if it's before or after the flex connector. But by my reading, current CPC says the sediment trap should be after the flex connector, unless that's not practical, since after the flex connector is closer to the inlet of the appliance.
I was scratching my head reading the California Plumbing Code trying to figure out where it has the requirement that the sediment trap be before the flex connector. After going back and looking at older versions of the CPC, this was in the 2016 and 2019 versions, but removed in the 2022 and 2025 versions.
Here's what the 2025 CPC states:
I agree with others that in reality it doesn't really matter if it's before or after the flex connector. But by my reading, current CPC says the sediment trap should be after the flex connector, unless that's not practical, since after the flex connector is closer to the inlet of the appliance.
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Fitter30
Well-Known Member
Trap to be piped correctly the gas flow has to enter the tee on top of the run (straight thru) and the bull ( side outlet) feeds the appliance. Bottom of run has a 3-4" nipple and cap. The run is vertical.
Jeff H Young
In the Trades
I spent way too much time looking all this up over several years and arguing about it but there was time Ca code did require the sediment trap upstream of flex argued with people over it, i put it at the control valve i know the changes were made and Ill just deal with it if I ever get called on my installations . most plumbers dont know code but we all think we do LOL kinda minor stuff actually took me hours to figure it all out.
Fitter30
Well-Known Member
Don't know why it would matter as long as it piped correctly. Support should come from a mechanical device not the drip leg to floor if needed.
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Fitter30
Well-Known Member
Pull the valve, street 90° (ell) screw the valve on , tee with trap and flex to wh valve. Only one fitting is needed.
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