I recently committed to the wife for a new 1/2 bath in the basement. We purchased a SaniFlo Macerating Toilet and a standard sink/vanity for install. The room is prepped and I am moving onto the plumbing. We have a dis-agreement. A little help from anyone here would be nice!

I have the sink draining to the macerator, the toilet as well.. there is a vent pipe for the macerator that I planned on "T eeing" into the existing 1st floor toilet vent. Is this right? Do I need to add anything else (AAV?? ) or is it as simple as that?

Do I need to vent the exhaust form the sink. As far as I can tell there is no vent for my slop sink in the wash room, wouldn't this be the same theory? If I do, will "T eeing" it into the exhaust from the macerator on the same line going out be sufficient?

Does all this make sense or did I do a poor job of explaining?

The system you are installing should have 2 pipes, a vessel, and a pump. One pipe goes from the pump to evacuate the vessel. The other pipe allows a free flow of air to allow water to be added to the vessel and to allow water to be pulled from the vessel. According to the code this pump line cannot discharge into a line that goes by a toilet or another fixture on that line even if it is wet vented. This pump line also cannot be of foam core pvc because it is not pressure rated for it. It must be connected at least 10 feet downstream of said fixtures. The vent needs to be connected to a dry line at least 6 inches above the flood rim of the highest fixture on that drain line.

The way I take it is that the evacuation line is below the toilet from the 1st floor. The evacuation for the upsatirs toilet is directly above where the new bathroom downstairs is. There is a "Y" with a clean out at the base of the upstairs toilet. I planned on replacing the "Y" with a new one including a second side to the "Y". Basically a double "Y" with a capped off clean out in the middle. 3" clean out capped, 3" evacuation line for upstairs toilet and required 1 1/2" evacuation line for downstairs vessel.

The vent for the vessel will be added to the vent line that currently vents the toiletand is the main line directly out to the roof. It will be around 1 foot before the " evacuation line for downstairs vessel.

The vent for the vessel will be added to the vent line that currently vents the toiletand is the main line directly out to the roof. It will be around 1 foot before the " for the upstairs evacuation where it splits to the vent. As far as I decifer form the Sani Flo directions this is correct.

My issue is, do I need a vent for the sink in the bathroom? The slop sink around the corner in the washer room does not have one, wouldn't it be OK to not have one for the sink in the new vanity in the basement?

"The vent for the vessel will be added to the vent line that currently vents the toiletand is the main line directly out to the roof. It will be around 1 foot before the "Y" for the upstairs evacuation where it splits to the vent. As far as I decifer form the Sani Flo directions this is correct."
"My issue is, do I need a vent for the sink in the bathroom? The slop sink around the corner in the washer room does not have one, wouldn't it be OK to not have one for the sink in the new vanity in the basement??"

By law, EVERY fixture that has a trap MUST be vented. The only exception to this rule is a floor drain. Vent the lavatory and while you're at it replace the illegal "S" trap on the slop sink and revent that back into the lav vent.

The pit vent should be a dedicated vent and not tied in with the house vent. The reason being that while a house vent draws in air from outside to relieve the suction caused by draining liquid. A pit vent not only draws air in when the pit pumps out but also exhausts air out when fixtures drain into the pit. However, I have read a installation instruction that say it's OK to tie the two systems togather. Most manufactures advise against it.

Good luck, Tom

Years ago they allowed a new thing, it was called a combination waste and vent. It played for a while then kind of died down and has now come back. You can go without a vent is you are not using a disposer and the riser is a pipe size larger than the trap. Legally you can use a 1 1/2" trap on a 2" drain. 2" is the minimum size for a combination waste and vent. And yes, it looks like an 's' trap.

That's what I figured. I got everything bought and I'll let you know how it turns out. I'm going to vent it LIke I am suppose too, so all should be good! Ill keep you informed. Thanks for the help!