plumbing adding a basement sink

[Limp Arbor]

My sewer pipe is cast iron and comes through the basement wall about

24" off of the floor. There is a Y fitting and elbow to turn the pipe 90deg and run it along the wall. The straight portion of the Y has a cleanout plug.

Question:

Can I put in a slop sink and using appropriate fittings run the P trap into the Y where the cleanout plug currently resides?

My obvious concern is getting backup of other waste water into the slop sink. About 4' upstream of the Y is a sanitary T running to a

1st floor toilet. Right below the toilet flange is a 2" wet vent that goes to two first floor sinks (a lav and a slop sink for the washer). The main continues around the basment walls to the back of the house for the kitchen and two second floor full baths (30' upstream of the first T).

My plan is to move the 1st floor slop sink along with the washer into the basement. The only thing left on the wet vent at the first toilet would be the sink in the 1st floor half bath. Currently no drainage problems at all with 2 1/2 baths, DW, and washer.

Waddya think?

[DerbyDad03]

A check valve between the sink trap and the rest of the system could prevent anything from backing up into the sink.

However, my brain might not be working this morning. If the existing cleanout is 24" off of the floor, how were you planning on getting the slop sink waste up to that cleanout?

Slop sinks are usually pretty deep so wouldn't the outlet of the trap be well below 24" from the floor?

[Limp Arbor]

I would either put cement blocks under the legs or hang it from the wall just high enough for the trap to fit.

[Art Todesco]

A check valve might not prevent sewer water from backing up into the sink. I've had that arrangement and what always happens is that the backup occurs fairly slow. The increase is so slow that a small amount leaks around the flap to the sink side. This continues and allows the sink to fill. Now, once you quickly empty the sink, you have a nice pressure differential between the 2 sides of the flap, and the flap is held tightly against its seat. When I discovered a sink full of water and it was about 5" from the top, I took a garden hose from the sump pit to the sink. I started running water from the faucet into the garden hose, and once filled, plunged it into the sink to start a siphon. Once the water was drained, no more came in and yes, it continued to pour rain outside for some time. I ended up putting a 1 1/2" plastic ball valve in the drain line. Of course, you have to be there to turn it.

I guess that's why the "backflow preventor, later installed by my village sewer department, was not a simple check valve. It was actually a flap controlled by a mechanical float. When the float started to go up in the unit, indicating a backup condition, it would mechanically, close the flap. Further backup would then press the flap tightly against the seat. Any water coming from the house would push another valve open and drain into a pit beneath the unit, where an ejector would force the house sewer water into the now backing up sewer. This unit was installed in a 3' diameter x 9' deep manhole in my front lawn. It was then covered with a square cover holding soil and grass, so it was almost invisible. I saw the bill from the installer .... it cost the Village about $5K to install. And, that was about 10 years ago. But, I digress.

[Joe]

A washing machine in a basement is never a good idea. If I proposed that to SWMBO it would be as welcome as a turd in the churn. Dragging loads of laundry up and down the stairs is OK for college kids and other under 20's, but in a family situation it truly sucks. Many families these days have laundry facilities on the second floor of well planned houses. Rethink your project, or better get some professional design help if you feel you must do it.

Joe

[Colbyt]

I think the suggested check might work for backflow. What do you intend to do for a vent to prevent the water in the trap from being sucked out?

[Limp Arbor]

I remember reading that a vent is not needed if you are within a certain distance to an underground pipe.

I think the existing wet vent that is right below the nearest toilet flange would prevent the trap in the new basement sink from siphoning. If not I can run a vent for the trap up and tie it into the vent above the sink on the 1st floor.

[Limp Arbor]

Here is a link to picture of my setup

[Marilyn & Bob]

Here is a link to picture of my setup

**

I would connect a 2" cast iron pipe into your lateral with a trap that has about a 2' vertical pipe it end. I would would then get a pump such as Little Giant 506065

and run the sink drain through that pump to the verticle pipe.

[Tony Hwang]

Hi, Our laundry room is in the basement and we have a sink there next to washer. I just went down there to take a look. Basically same as what you are trying to do. When house was built builder finished the basement.