Plumbing Questions - venting

[Jeff7181]

I have a new home that we just built last year. We paid the builder to plumb in the waste water pipes for a toilet and two sinks in the bathroom so we didn't have to bust up the concrete in the future to finish a bathroom and bar sink.

The toilet is upstream from both of the sinks and they run to the sewage pump basin about 30 feet away because the sewage line is about 3 feet up from the basement floor.

There is a vertical dry vent directly above the sewage pump basin that the builder pointed out to me for use when I get a sewage pump installed.

I don't see any additional dry vents where the bathroom is. I will be hiring a plumber to put the sewage pump in, but I'd like to educate myself so I know how to tell if they're doing something stupid, so my questions are:

First of all, do I even need a separate vent closer to the bathroom considering the sewage basin would be vented, but it will be 30 feet away from the bathroom? I've read some things saying a toilet doesn't need a vent, it will vent itself and refill the trap as part of refilling the bowl.

Second, if I do need a vent, can it be a wet vent? And if so, do I need to take into account anything regarding pipe size and number of fixtures upstream from where I tie into the existing waste water pipe?

And finally, considering that the toilet is upstream from two sinks, should I be concerned about the toilet drawing the traps for the sinks dry when it flushes?

Again, I will be having a licensed plumber installing the sewage pump eventually, I'm just trying to understand what's correct so I can make sure the plumber doesn't do anything shoddy.

*EDIT* Oh... one more question. Considering the sewage pump only has to lift about 10 feet and will then dump right into the existing waste water pipes, is there any benefit to using a grinder pump vs. a sewage pump? It would be nice if an occasional feminine hygiene product made it into the toilet wouldn't cause a big problem. It won't be a problem for my wife and I, but when we have guests, many women/girls just don't understand certain things shouldn't go down the toilet. I don't know if a grinder pump is any more capable of handling that sort of stuff than just a sewage pump...

 

[NetWareHead]

All fixtures need a vent. Period.

At the distance you specify between the toilet and sewage pump (30 feet), you will need to vent the toilet. What you heard about the toilet refilling it's own trap is true but the reason for the vent is to help the flushed water/solids go speedily down the line and not cause a vacuum. Such a vacuum could pull water out of other traps causing them to lose their water seal. This is especially important when you have sinks downstream from the toilet. Or you could just get lazy flushes requiring more than one flush per use and frequent plunging.

Regarding the wet vent, the plumbing codes I've seen specify a toilet needs to be installed downstream of all fixtures. In your case the toilet and other fixtures cannot share a went vent and must be individually vented. Each fixture (sink, shower etc...) you are draining sets the correct size of the wet vent. Lookup "fixture units" to get an idea of how many you can vent.

Regarding the grinding pump, I'd say if you can foresee unmentionables being flushed, than get a grinding pump and save yourself the disgusting hassle of cleaning a sewage ejector pump one day. I vividly recall flushing a he-man action figure down the toilet when I was a boy and my father having to fish it out of the sewage pump and clean up the overflow. He was not happy one bit.

Above all, your plumber should know the local code for your area and should be your final reference for venting and code related questions.

 

[Greenman]

Depends on where you live and what code they're using. IBC doesn't require a water closet be vented. The sinks should be vented at the sanitary tee where the trap arm enters the wall.
You don't ever want to have to pull the lid off of the sump where the waste ejector resides, and you don't want to see the bill or the mess a plumber is going to leave if you don't do it yourself. Buy the best unit made.

 

[Jeff7181]

I took a picture before the concrete was poured... so you can see how the plumbing is run under the floor.

What you see there is a for a full bath. Instead we're doing a half bath and bar sink. Other than tying into existing waste water for wet vents, would putting Studor vents on each of the sinks be sufficient venting?


uploadphotos

 

[Greenman]

Based on the water level along that waste pipe, it doesn't appear to have any fall. That's bad.
The two 1 1/2" stacks should have vents above them. If they don't your builder screwed you. You might be able to get away with air admittance valves, depending on local codes.

 

[NetWareHead]

You mentioned that toilet is 30 feet from the sewage pump and vent with no additional vents along that line. Based on this table, that is too far away. Hopefully I'm wrong about this...

 

[Greenman]

That's correct for a fixture that requires venting. Under the IRC a water closet doesn't require a vent. I don't know where anyone actually goes by the IRC, but it's there. It probably works, but I wouldn't do it. Easy enough to pop a hole in the slab and add a vent, though finding a place to run it up through the house can be a challenge.

Another option would be a water closet with a built in waste ejector, then abandon the questionable plumbing.

 

[Red Squirrel]

I would just vent it, it's easy to do it now, vs later if you realize you have siphoning issues. You can even have venting line go horizontal and go join up with the main stack, that would be an acceptable way of doing it if you don't want another penetration. (I don't know about code, but logically I can't see why not)

As a side note I would not like the idea of the sewer line being higher than the lowest point in the basement. That seems like a recipe for disaster. Ensure there is a backflow provention valve before the bassin and some kind of alarm point that sounds an alarm if basin gets too full. Probably want two sump pumps too. (for redundancy).

 

[Scarpozzi]

You don't have to vent the toilet itself, but you have two sinks you can run vents from that will be sufficient for the line. If the sinks are more than 6 feet apart, I would vent them both, but join them together in the ceiling before taking one pipe out.

 

[Jeff7181]

I would just vent it, it's easy to do it now, vs later if you realize you have siphoning issues. You can even have venting line go horizontal and go join up with the main stack, that would be an acceptable way of doing it if you don't want another penetration. (I don't know about code, but logically I can't see why not)

As a side note I would not like the idea of the sewer line being higher than the lowest point in the basement. That seems like a recipe for disaster. Ensure there is a backflow provention valve before the bassin and some kind of alarm point that sounds an alarm if basin gets too full. Probably want two sump pumps too. (for redundancy).

That's the way all the houses on the street are and it's not uncommon as far as I know. It's also how they've avoided having an ejector for the entire house. So all that's needed is an ejector for the basement plumbing. There's a backflow prevention valve on the main sewer line going out of the house.

Other than the cost of the valves, is there a reason to vent back to the main stack rather than install air admittance valves? Local code allows it - I already have one under my kitchen sink that the builder installer.

When I have the sewage pump installed, I'll definitely have them take every precaution and install every device possible to alert me to a problem before it results in a leak or broken plumbing.

 

[WHAMPOM]

I took a picture before the concrete was poured... so you can see how the plumbing is run under the floor.

What you see there is a for a full bath. Instead we're doing a half bath and bar sink. Other than tying into existing waste water for wet vents, would putting Studor vents on each of the sinks be sufficient venting?


uploadphotos

That is beautiful, three unnecessary 90 degree elbows where one could have run a straight pipe end to end.

 

[Greenman]

That is beautiful, three unnecessary 90 degree elbows where one could have run a straight pipe end to end.

I totally missed that! I was so focused on trying to figure out if there was any slope on the pipe it never occurred to me to look at the round about path.
Good eye.