Valid vent for basement bath?

bdowden · 09-29-2011, 04:38 PM

Hi all.

We had our house built in 2009 (we live in Connecticut) and thought ahead to get rough-in plumbing in the basement for a future full bath. Since it's below sewer line we had them install an ejector pump in the corner of the basement. The standard piping is present (photo 1) - a 3" toilet, a 2" pipe under the slab for the shower drain, and a 2" pipe for the vanity.

Based on my understanding, the vanity drain pipe will wet vent the others, and I'll need to extend that pipe to the ceiling and connect it to the main vent stack.

After talking to the plumbing company that installed everything, they said if there wasn't a dedicated vent they could tie into a waste drain and that would be ok. After searching various sites I don't think they can do that.

I looked through the pictures we took while the house was being built and unfortunately we didn't have the foresight to take pictures of the basement ceiling. I could go through and remove all the insulation but that would be messy and I'm sure I'd end up not finding anything.

I did, however, find this picture:

This is the first floor kitchen, the master bath is behind. As you can see the bathroom sinks drain into the right-side pipe (2"), and there's another pipe to the left (1.5"). Looking at these pipes in the basement, the left-hand side connects to the pipe connecting to the bathtub with a T fitting. The other drain pipes that connect to a "main" line are using wyes.

I'm fairly confident the left hand pipe is only a vent, not a drain. Since this pipe connects above the 6" requirement, can I use this as a vent for the basement bathroom? I would need to add another T fitting in the basement ceiling, but that's easy enough to do.

Although I'm 97% sure it's only a vent (based on its location and other pictures we took), how do I figure out if it actually IS? Is there any way?

Thanks!

**TheEplumber** · 09-29-2011, 08:09 PM

Is your sewer pump vented yet? If so, it might be possible to tie into that vent for your bathrm. group. If not, then you will need to vent the pump as well.
The 2" lav drain does appear to be the toilet wet vent. Since a toilet requires a 2" vent you will not be able to use the 1.5" vent as proposed in picture 2.
I'd poke around the basement ceiling for a 2" capped pipe. A good plumber would supply the vent your looking for. Also, call the plumbing inspector and ask if AAV's are allowed in your area as an alternate venting method.

bdowden · 09-30-2011, 12:30 PM

Thanks for the information. I called the plumbing inspector a couple of months ago (we have been planning the basement project for over a year) and he said AAVs cannot be used for an entire bathroom group.

The sewage pump is vented, although the vent ties back into main waste stack and is only 5 feet off the ground. Is it ok to put a wye onto the pump's vent stack, extend a pipe up, and then connect the vanity vent to that? The distance from the vanity vent to the pump is around 20 ft, although it could be more depending how the vent line is run.

I can post a picture of the pump setup when I get home from work, but both the waste and vent pipes from the pump go into the main waste stack, the vent being higher than the waste.

**TheEplumber** · 09-30-2011, 12:52 PM

Please do post a picture of the pump. I have a hard time believing the vent ties into the waste. But there a lot of code variations so who knows.
I usually have to vent pumps out separately, depends on inspector and conditions.

bdowden · 09-30-2011, 04:43 PM

Here is the picture of the pump. Sorry for the poor quality, I don't know where our camera is so I took it with my iphone.

The pipe in the rear connects to the sewer line (1 foot above floor level). The P trap is a line connecting to a mini-pump that is connected to a dehumidifier and the furnace (for any moisture that comes out of it).

Since the house had to be inspected before the CO was issued, I'm assuming that this is OK for code in my area. Everywhere I've read says the pumps need to have a dedicated vent but this one obviously isn't. I find it odd that it's connected back into the main drain but I'm not a plumber.

The drain pipe for the toilet is actually a 4", not a 3" as I previously stated. I'm not sure if that makes any difference.

Thanks!