Hi-rise plumbing

DaveC426913

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I work on the 24th floor. In the loo, I noticed a standard 4" drain in the floor about 6 feet from the toilets. When the toilets flush, you can clearly hear water gushing down the drain. I'll bet if I shone a light down there, I'd be able to see it dropping down the vertical. i.e I suspect it come out at a straight T-joint, a foot below the drain.

Is this not risky - but more to-the-point - highly unsanitary? I mean, if there's solid waste flowing and sloshing just a foot below that grill - even in normal operation - isn't that spewing bacteria-laden particles into the bathroom proper?
 

russ_watters

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Shine a flashlight into the drain; I'd be shocked if it wasn't protected by a trap.
 
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He said toilets, not sinks!
Sounds like a code violation to have the toilets drain into a pipe that is open to the loo. As 'it' goes down the air is displaced up into the room through the floor drain. Bad situation!
 

berkeman

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He said toilets, not sinks!
Sounds like a code violation to have the toilets drain into a pipe that is open to the loo. As 'it' goes down the air is displaced up into the room through the floor drain. Bad situation!
No, please re-read the diagram. It says drain or sink. Floor drains will generally have p-traps too, I believe. I'm more familiar with electrical codes and not plumbing codes, but I'll try to find a code section to post...
 
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Properly built floor drains have water traps and ultimately they will connect to the same soil drain or stack as the toilets are connected to. How close they connect will determine how easily you can hear the toilets washing past them.

The floor drains get water for their traps from trap primers which drip water into them periodically. If you ever look at a urinal or toilet flush valve and see a small 3/8" water line mysteriously running from them into the wall, that is one way the trap primers get their water. Every time you flush one of them you send a little spurt of water to a floor drain.

These systems are notoriously fragile and often go bad allowing traps to dry out. A dry trap would definitely be noisier than a full one. It would also allow sewer gases to pass through to that room. Custodians typically catch on to this and will allow some mop water to go down the drain every night, but not all of them know about it.

Ultimately your toilets, sinks, urinals, water fountains, showers, floor drains, vents etc ad nauseum all are connected and if there's ever a clog then sewage could back up to the first lowest drain above the blockage. Could be a floor drain, could be a shower. Fun stuff.
 
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CWatters

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There are also concentric traps that can be serviced from above. Also used for wet room shower drains.
 
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Theres another part of the system in houses, the plumbing vent in the roof can get clogged with leaves and debris and cause issues with flushing. I imagine high rises have something similar that must be kept open to the air.

https://m.wikihow.com/Vent-Plumbing
 

jim hardy

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When the toilets flush, you can clearly hear water gushing down the drain.

I've seen that too where i worked. Indeed i could look in and see water run by. But never any solids and it never smelled..
Had i seen solids i'd have known somebody took a shortcut and abused the concept of "wet vent"

upload_2018-10-18_13-9-48.png

In that image the toilet is vented through the vertical lavatory drain line..

but i think (dont know for sure) it was one of those automatically primed drains instead, as previous post mentioned. . See this short video:

Armed with those basics you can observe further and figure it out...
I love learning 'tricks of the trade' through studying everyday experiences. .


old jim
 

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DaveC426913

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Shine a flashlight into the drain; I'd be shocked if it wasn't protected by a trap.
What makes me think it's draining directly is that I can hear it clearly. The high-pitched sloshes that you hear directly from water, rather than the lower-pitched, muffled sounds filtered through a trap.

I doubt I wold hear such sounds coming from my shower drain at home, since it will be blocked by the water in the S-trap.

I'm loathe to get on my knees and look into a drain with a flashlight in the middle of a busy office washroom...
 
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DaveC426913

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No, please re-read the diagram. It says drain or sink. Floor drains will generally have p-traps too, I believe. I'm more familiar with electrical codes and not plumbing codes, but I'll try to find a code section to post...
I'm familair with P-traps and S-traps. But the water-filled trap should muffle the otherwise very clear sounds of gushing water.

As in your diagram,. I should be hearing sounds coming from everywhere except directly out of the drain.
 

anorlunda

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I'm familair with P-traps and S-traps. But the water-filled trap should muffle the otherwise very clear sounds of gushing water.
Yes, unless the water in the trap evaporated away. See #6
 
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Tom.G

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Another fun fact, just slightly off-topic.
In high-rise buildings the drains have a short horizontal section every few floors. Without that feature, by the time the solids get to the bottom they have enough kinetic energy to blast right thru the pipe bend that goes out to the city sewer.

p.s. Sounds like a problem that was learned the hard way!
 

CWatters

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If it's a top access trap perhaps someone forgot to put the insides back in.
 
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Sounds like the trap is dry or not present. Feel free to dump some water down there. A gallon would be more than enough to fill a 3 or 4 inch trap. Shine a light down it afterward, if you see a pool of water you are good to go. If you just see a bend in the pipe then there's no trap and you should ask facilities to fix that.
 

DaveC426913

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I can't believe I'm actually considering doing this in the name of science.

Grabbing a flashlight and a bucket and getting down on my hands & knees in the stall of a bathroom on the 24th floor of the office building where I work.

Is this one of those moments where, after it's ruined your life by going viral, you look back and think to yourself "...sure picked an unlucky day to wear the latex gimp suit to work..."
 

DaveC426913

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OK, as a first round of study, I examined the duration and timing of the water noises. I recorded it so as to minimize estimation error.

This is a chart of the sounds.
toilet flush.png


The kabloosh lasts five seconds, and then there is a full three second gap of silence before the tinkling sound in the drain.
The sound from the drain starts quite abruptly and then ends quite abruptly 5 seconds later (i.e. as if controlled).

This to me, indicates the tinkle is either actively or passively injected into the drain after the flushing is completed. Likely the mechanism that keeps the trap primed with water.

Looking down into the drain, I can see water about a foot down - surely the water in the trap. It jostles during flushing but there is no flow to be seen.
The tinkling, on the other hand, is quite apparent. It comes from higher up, about 6 inches below the grill, and is only maybe 250mL, if that.

I would say this drain is not only working correctly, but is designed to actively prevent evaporation of the trap water.

I am satisfied with my results.

When will my grant money arrive?
 

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DaveC426913

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Did you wear a janitor's jumpsuit for Halloween?
This is the first year in decades that I did not wear a 'ween costume to a job.
Something about this place... :frown:
 

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