Reporting on S-Traps

[Mike Lamb]

I am curious as to how others report on S-traps which is rarely a simple fix. I don't know if I have been giving it short shrift. All I usually do is report that the kitchen or whatever has an improper S-trap, and that is it. I don't tell anyone to consult a plumber, or to get it fixed.

I verbally tell my client the ramifications and that if they smell sewer gas just run a little water to prime the trap.

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[Les]

Mike we do the same as you. Sometimes, we don't even write it.

I am curious what the brethren will say about this.

[gtblum]

My boiler: The waste line under the sink has an S trap. This is considered an improper installation by current standards. This can siphon the P trap dry and allow waste gas to escape into the home. However, this is known to happen only in a rare occurrence.

Same as you, I tell them to run the water or as I understand it, it's now acceptable to install a mechanical vent?

My brother once walked me to his kitchen sink while asking why he smelled his septic. Sure enough, an empty S trap. Kind of cool to experience it first hand. And, not in my own house. []

[Chad Fabry]

The waste line under the sink has an S trap. This is considered an improper installation by current standards. This can siphon the P trap dry and allow waste gas to escape into the home. However, this is known to happen only in a rare occurrence.

Did someone steal your password and post this?

[gtblum]

The waste line under the sink has an S trap. This is considered an improper installation by current standards. This can siphon the P trap dry and allow waste gas to escape into the home. However, this is known to happen only in a rare occurrence.

Did someone steal your password and post this?

Look. You get who they give you for instructors at licensing school. I blame them.

[Marc]

"A trap fitting in the drain line of the kitchen sink discharges straight down instead of sideways. Gravity and momentum tends to suck the water out of it thus allowing gases from the municipal sewer line to enter the house through the trap. It's an older style of drain trap that plumbers stopped using long ago. If you experience problems with sewer odors coming from the kitchen sink, replace this trap with one that discharges towards the back of the sink cabinet or otherwise sideways. You'll need a plumber to do it."

Marc

[Greg Booth]

The waste line under the sink has an S trap. This is considered an improper installation by current standards. This can siphon the P trap dry and allow waste gas to escape into the home. However, this is known to happen only in a rare occurrence.

Did someone steal your password and post this?

Look. You get who they give you for instructors at licensing school. I blame them.

...........I'm pressing my "like button" again [:-graduat..........Greg

[Tom Raymond]

3 of the 4 sinks in my house have s traps. They never go dry.

The drum trap on my bathtub goes dry once or twice a year, always in summer, always around a frontal system and major swings in the barometer.

Blum, that boiler plate is a mess.

[Erby]

...The waste line under the sink has an S trap. ...This can siphon the P trap dry...

Huh?

Anyway

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An 'S' trap is being used on the drain line at the. 'S' traps are prone to siphoning (sucking the water out of the trap) which can let sewer gas come up into the house and stink it up. This type of trap may have been allowed when this plumbing system was installed. Traps are designed and installed in a prescribed manner to prevent sewer gases from coming up out of the drain lines. Generally accepted building practices no longer allow the installation of 'S' traps due to the siphoning issue.

If you smell sewer gases coming out of the drain, a temporary fix is to run some water down the drain to fill the "S" trap. The long term solution is to replace the "S" trap with a "P" trap that doesn't allow for siphoning the trap dry. (See photo below. S trap at top - P trap at bottom.) Consult a good plumber and leave it alone or replace it as you and he agree would be best.

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You ever notice that when you put something up here from your boiler plate, you realize you need to change it a bit (or a lot)?

[Erby]

The drum trap on my bathtub goes dry once or twice a year...

Perhaps if you used it more often...

[:-monkeyd[:-monkeyd[:-monkeyd

(You knew someone was going to say it:)

[John Kogel]

I call out the S-trap, because if I don't, my client's uncle will say I was a clutz for missing it.

The drain under the sink is not vented correctly. If problems occur such as clogging or odors, have a plumber install an Air Admittance Valve (AAV) or "cheater valve".

I know, not allowed in Chicago, but that works for me here.

[Marc]

I call out the S-trap, because if I don't, my client's uncle will say I was a clutz for missing it.

The drain under the sink is not vented correctly. If problems occur such as clogging or odors, have a plumber install an Air Admittance Valve (AAV) or "cheater valve".

How would an air admittance valve help? That vertical section after the trap will still siphon out the trap.

Marc

[John Kogel]

I call out the S-trap, because if I don't, my client's uncle will say I was a clutz for missing it.

The drain under the sink is not vented correctly. If problems occur such as clogging or odors, have a plumber install an Air Admittance Valve (AAV) or "cheater valve".

How would an air admittance valve help? That vertical section after the trap will still siphon out the trap.

Marc

Not if it is installed correctly. A Tee goes in after the trap.

Island sinks have vertical drains and a cheater valve. New construction, it's allowed here.

PS, I avoid mentioning sewer in my reports unless it is a sure thing they are on sewer.

A few years back my clients discovered their new house had a plugged up septic tank in the back yard. Listing said sewer. I had copied the info into my report as usual. That info was dead wrong. Then I chewed my fingernails for a year when the realtors got hauled into court. Lucky me, my clients asked me to be a witness for their side and I only lost one day out of my life.

So, if it is underground, I do not see a reason or obligation to report it.

[kurt]

Reality for me is they don't siphon. At most, there's a little gurgle-burp, but they never siphon enough to allow sewer gas by.

Water sticks to the sides of any pipe as it drains; air circulates up the middle of the pipe. It's hard to get siphoning unless there's some other complete mess in the DWV system.

That said, of course I report it (so they hear it from me before they hear it from their brother in law the plumber) and indicate repairs are problematic and possibly expensive because finding a suitable and accessible vent connection is often a Holy Grail undertaking.

[Eric B]

I call out the S-trap, because if I don't, my client's uncle will say I was a clutz for missing it.

Agreed. I'd be more interested in what a qualified plumber would say. I'd be punting onto his shoulders.

[mjr6550]

I tend to ignore them if they were installed at a time when they were permitted. I flag them on recent renovations.

[gtblum]

Blum, that boiler plate is a mess.

Tom

You ever notice that when you put something up here from your boiler plate, you realize you need to change it a bit (or a lot)?

Yup! It sucks. I'll be rewriting it.

[Chad Fabry]

The waste line under the sink has an S trap. This is considered an improper installation by current standards. This can siphon the P trap dry and allow waste gas to escape into the home. However, this is known to happen only in a rare occurrence.

Did someone steal your password and post this?

Look. You get who they give you for instructors at licensing school. I blame them.

...........I'm pressing my "like button" again [:-graduat..........Greg

You guys are funny. Not as funny as Blum's boiler plate, but pretty funny.

[Mike Lamb]

Or,

"The kitchen sink has an improper s-trap drain. It sucks more than a proper drain configuration but it's not a big deal."

[Les]

Mike, how would I handle it if the s trap was in the bathroom and not the kitchen?

[Marc]

I have to agree with Mike that an S-trap sucks water better than P-trap but it is indeed a big deal because it sucks too much, leaving it dry sometimes[:-dunce]

Marc

[Mike Lamb]

Mike, how would I handle it if the s trap was in the bathroom and not the kitchen?

I was being glib with the, "sucks more," double entendre. Are you asking because of the added suction a toilet flush would bring?

Unless someone or something can convince me otherwise I will continue to treat s-traps bathrooms or kitchens the same as my OP.

[Bill Kibbel]

I don't mention s-traps unless it's recent construction or recent kitchen or bath remodel.

Once in 29 years a client called to tell me the plumber installing a new sink said the trap is "illegal" and shouldn't have "passed" my inspection. This was a 260 year old house with a 1930s kitchen. I had one similar call for a drum trap.

[Bill Kibbel]

Read Jim K's post #6 here: https://inspectorsjournal.com/forum/top ... IC_ID=5929

Should be in the home inspector school textbook.

[kurt]

Half of Chicago metro is still on drum traps.