Plumbing Vent for Toilet

[Reach4]

If you can vent that lavatory, and run 2 inch from there to join the toilet waste with a wye before the toilet waste joins other stuff, then the toilet venting will be taken care of. We say the lavatory is wet-venting the toilet. Wet vents can go horizontal (where horizontal still implies the right slope-- usually 1/4 inch per foot.

Many places now disallow whole house traps, tho they have some advantages and some disadvantages. I expect yours is grandfathered in.

 

[wwhitney]

The plumbing system is in my house not in NYC. Their is a 4" cast iron p-trap before it leaves to the public sewer system. Before this p-trap their is a 4" plumbing vertical vent.

I think you may find that what you call a 4" vertical vent before the whole house trap in fact just rises to above grade and then goes out a side wall to terminate not far above grade. In which case it is more properly called a fresh air inlet for the whole house trap. See, e.g. https://www.radianttechnology.net/fresh_air_inlet.php

And if that's correct, that 4" pipe is not a vent for the plumbing and can not be relied on as such.

Cheers, Wayne

 

[Sponsor]

 

[Reach4]

And if that's correct, that 4" pipe is not a vent for the plumbing and can not be relied on as such.

Then under IPC, an AAV on the lav could provide the needed venting.

 

[Jeff H Young]

I think the house trap has nothing to do with this unless your planning on adding a toilet downstream of the trap?
nearby vent almost surely wont work without changes

 

[Vin_ny]

If you can vent that lavatory, and run 2 inch from there to join the toilet waste with a wye before the toilet waste joins other stuff, then the toilet venting will be taken care of. We say the lavatory is wet-venting the toilet. Wet vents can go horizontal (where horizontal still implies the right slope-- usually 1/4 inch per foot.

Many places now disallow whole house traps, tho they have some advantages and some disadvantages. I expect yours is grandfathered in.

Yes, mine was grandfathered in since 1947. What are the disadvantages/advantages? On a separate note, I was also thinking of installing a backwater unit.

 

[Vin_ny]

I think you may find that what you call a 4" vertical vent before the whole house trap in fact just rises to above grade and then goes out a side wall to terminate not far above grade. In which case it is more properly called a fresh air inlet for the whole house trap. See, e.g. https://www.radianttechnology.net/fresh_air_inlet.php

And if that's correct, that 4" pipe is not a vent for the plumbing and can not be relied on as such.

Cheers, Wayne

Yes, you are correct it is just as you described. Ok, yes, I was not going to depend on this, just was asking about different possibilities.

 

[Vin_ny]

Then under IPC, an AAV on the lav could provide the needed venting.

I'm going to stay away from AAV, but I appreciate your suggestion.

 

[Reach4]

Yes, mine was grandfathered in since 1947. What are the disadvantages/advantages? On a separate note, I was also thinking of installing a backwater unit.

You can search out more, but my recollection is they tend to clog requiring fairly frequent cleaning. Also they also don't allow the multiplicity of houses to provide venting for the city sewer.

The advantage I remember seeing is if there is a bad vapor in the sewer, such as gasoline poured in, the trap could stop the vapors from getting to the house plumbing. I have also seen thoughts that they inhibit rats coming in thru the sewer, but I think rats may be divers that can make it thru the traps.

Regarding backwater valves, best are the "normally open" type. The normally-closed units, with a flapper hanging down, will tend to get held open by debris. The normally open type have their outlet lower than the input. So you have to make allowances for that.

Best is to only have the below ground flows go thru that valve, so above ground floors can continue to function.

The gold standard in anti-backup for sewers is the "overhead sewers" where basement loads feed a vented sealed pit that has a pump. The pump pumps up and the pumped waste then drops in from a level higher than ground level.

 

[Vin_ny]

You can search out more, but my recollection is they tend to clog requiring fairly frequent cleaning. Also they also don't allow the multiplicity of houses to provide venting for the city sewer.

The advantage I remember seeing is if there is a bad vapor in the sewer, such as gasoline poured in, the trap could stop the vapors from getting to the house plumbing. I have also seen thoughts that they inhibit rats coming in thru the sewer, but I think rats may be divers that can make it thru the traps.

Regarding backwater valves, best are the "normally open" type. The normally-closed units, with a flapper hanging down, will tend to get held open by debris. The normally open type have their outlet lower than the input. So you have to make allowances for that.

Best is to only have the below ground flows go thru that valve, so above ground floors can continue to function.

The gold standard in anti-backup for sewers is the "overhead sewers" where basement loads feed a vented sealed pit that has a pump. The pump pumps up and the pumped waste then drops in from a level higher than ground level.

Interesting, thanks for the feedback! I will do more research. Thank You all @Jeff H Young , @Terry , @Reach4 , @wwhitney and everyone else I might have left out for your helpful advice. I will keep you posted for any changes.

 

[Jeff H Young]

You can search out more, but my recollection is they tend to clog requiring fairly frequent cleaning. Also they also don't allow the multiplicity of houses to provide venting for the city sewer.

The advantage I remember seeing is if there is a bad vapor in the sewer, such as gasoline poured in, the trap could stop the vapors from getting to the house plumbing. I have also seen thoughts that they inhibit rats coming in thru the sewer, but I think rats may be divers that can make it thru the traps.

Regarding backwater valves, best are the "normally open" type. The normally-closed units, with a flapper hanging down, will tend to get held open by debris. The normally open type have their outlet lower than the input. So you have to make allowances for that.

Best is to only have the below ground flows go thru that valve, so above ground floors can continue to function.

The gold standard in anti-backup for sewers is the "overhead sewers" where basement loads feed a vented sealed pit that has a pump. The pump pumps up and the pumped waste then drops in from a level higher than ground level.

Just Wondering If the "Overhead sewers" are allowed because they are desired or only when a gravity drai.n is deemed not practical or for IPC areas where thier code prohibits drains to be pumped that could be gravity drained.
my understanding is if you are building a new project and the sewer lateral is deep enough that you are required to gravity drain. if as an after thought plumbing is added in a basement and building drain enters too high then I see it as impractical to force property owner the burdeon of running a new drain out to lateral.
Anyway My understanding is its not just an option whether to pump or go gravity.

 

[Reach4]

Overhead sewers are not an IPC thing. They are a basement think in areas with sometimes high ground water.

So a gravity floor drain may work fine to the sewer. Until a big rain and the sewers get full. How do they get full? Could be combined sewers. Could be people are pumping their sump pumps into the sanitary sewers when they are not supposed too.

So anyway, with enough water, the sanitary sewer overloads, and sends water the wrong way -- into basements. It's not that the city sewer is too high. It is that the city sewer is too full.

Overhead sewers are more common in new construction, because retrofitting to overhead sewers is expensive. There are cheaper ways to deal with this, especially for retrofit. But those are not as good as overhead sewers.

Now the name overhead sewers is a funny name, but that is what they are called. The sewer normally leaves the basement a few feet above the basement floor. The line dives down to the level it will continue at toward the city sewer.

 

[Jeff H Young]

We dont put roof drains or foundation drains into sewer we dump it in the stormwater system. If we were to build with a basement it would be expected that plumbing fixtures gravity drain to sewer . if you had drains around foundation and it was possible to gravity drain those to a storm drain or if on a hillside and drain out to daylight some how that could be done too , generaly . Both codes though ask for gravity drainage where possible from what I see

 

[Reach4]

If you are on a hillside, you probably don't have high ground water.

 

[Jeff H Young]

we still put french drains in and daylight out rain water. and we still have plumbing fixtures that need to gravity drain out to the sewer. its probebly just a requirement that gets ignored and everyons just pumps whenever convieniant Im thinking

 

[Reach4]

we still put french drains in and daylight out rain water. and we still have plumbing fixtures that need to gravity drain out to the sewer. its probebly just a requirement that gets ignored and everyons just pumps whenever convieniant Im thinking

But you don't have a lot of active sump pumps in basements, do you?

 

[John Gayewski]

But you don't have a lot of active sump pumps in basements, do you?

There are some dumb builders. That hire dumb plumbers. Yes I've been in houses that pump their 10 ft basement 24-7. It's a constant worry for the unexpecting owners. I result think a lot of the time contractors of all types tell the customer "yeah we can do that." Not really thinking about weather it's good or not.

 

[Jeff H Young]

But you don't have a lot of active sump pumps in basements, do you?

I guess Id have to say no not that many active basements commercial jobs close to ocean I suppose.
Mostly What I was talking about was sewer systems and pumping waste from bathrooms etc. we can only pump when there is dificulty in putting gravity drainage system in.

 

[Reach4]

Towns don't like their sewers backing up into homes. Sometimes they will have programs to pay for part of putting in overhead sewers or other fixes.

 

[Jeff H Young]

Why don't they use a B/W valve ? that's what my house has for first floor the next upstream manhole is a couple feet higher than my floor. they must have amendments to the code to allow pumping when there is no need would be my guess unless they just pick and choose enforcement?

 

[Reach4]

Why dont they use a B/W valve ?

1. Backwater valves often leak, with the flappers almost certain to leak once installed for a while.
2. Depending on where they are installed, they block off waste when functioning properly.

https://www.floodexperts.com/services/flood-control-systems/ is another system, which costs less.

Try these two searches on a search engine:
"overhead sewers"
"overhead sewers" program