I am looking to finish my basement and as part of the renovation, I'd like to install a bar complete with a sink and dishwasher (and beer taps of course). Attached (once I get enough rep) is a diagram of what I am working with. From what I know, there are 3 options for installing the sink

  1. Regular ol' gravity, 1/4" drop per foot of run
  2. Trenching out a line to the drain
  3. Pumping the waste up

I'm pretty much going to say that I don't want to do number 2. #3 is the option of last resort as I don't want to listen to the thing running every time I turn on a faucet for the sink or run the dishwasher. That leaves me with option one.

As you can see from the diagram, there's a 3" PVC drain pipe that currently runs in the ceiling and out down the far wall. There are water lines that run parallel to this drain line. The two circles on the diagram are current PVC pipes sticking out of the ground along the foundation wall (put in the room for clarity). The one on the top is labeled 2" and the one on the bottom of the diagram is 3". The drain line in the ceiling connects to the one on the bottom. [There's also a sump pump in the ground behind the door on the bottom that's not on the diagram if that matters any]

Racking my brain, the 3 options that I see are

  1. Get rid of the bottom door and run along the walls to the drain. Depending on where the sink and d/w are, that's a run of about 36.5'~ 43.75' which would require a drop of about 9~11". That doesn't seem like very much
  2. Run it up along the stairs and over to the 2" pipe. That's a shorter run, but it'd require me to build a wall across and chop up the storage area.
  3. Bite the bullet and do option 3. I could pump it up into the 3" pipe that's already in the ceiling.
  4. Other??

I guess my questions are

  • 1
    3 isn't an option. Do not pump up sewage. You will have problems. Breaking up concrete and recementing is not expensive or hard.
    – DMoore
    Commented Aug 8, 2013 at 6:29

1 Answer 1


As DMoore suggested, running below slab is a viable option. Are you sure there are no lines running under the slab that may be closer?

The sink does need to be vented. Ideally, it should run up to an existing vent pipe that continues up through the roof. Some jurisdictions allow a mechanical vent which can be simply hidden in the wall, though the mechanical portion should be accessible for service and repair.

The drain slope is measured from the trap's outlet "invert", the lowest inside portion of the outlet pipe. Since pipe walls are parallel, you can actually measure the slope at any convenient surface, but for calculating if you have enough drop, use the invert. To tie into existing pipe, cut out a section and install a Wye or long turn Tee fitting. If none of the pipes can be moved to enable slipping into the hubs, the pipe can be cut farther up to enable gluing the fitting, then the butt ends are connected with a no-hub coupler.

As long as the pipes are waste pipes and not vents or something else, yes you can tie into them.

You should avoid pumps. But FYI, they are typically sort of a trash can with a pump inside. It could be placed on the floor in the storage room and the sink can easily drain into it. Such devices do get more complicated with floor level drains such as showers and toilets, but in your case, it's simple.

  • I don't know exactly where the lines run under the slab. From what I read, they tend to run toward the street, which is up on the diagram. The sink/DW would be right smack in the middle of the basement, so not sure there would be any lines to tap into. Most of the lines from upstairs run in the joists as shown in the diagram. I saw that there is a product from saniflo that would pump the waste water up. Other than noise, why should I avoid pumps like this? Commented Aug 8, 2013 at 21:21
  • It's just that gravity is much more reliable than mechanical devices. There's issues with power outages and the mechanism can get clogged with debris. The thought of a sewage holding tank in a habitable space makes me a bit uneasy, though it's more psychological than physical. I would only go this route if there really is no other option.
    – bcworkz
    Commented Aug 9, 2013 at 22:53

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