We recently moved into a new (to us) house with an unfinished basement where I would like to install a utility sink.


  • All plumbing runs through the basement, adjacent to the area where I would like to install the sink
  • On site septic
  • Located in PA USA

As stated, all plumbing is near the proposed location (easy access to fresh water lines), but I'm not sure if it is feasible to tap into the drain line shown in the picture.

Note that the top of the drain where the straight edge is in the picture is about 23" above floor. To the right of the straight edge is a clean out (not in frame further right is another clean out & from there the drain turns and exits through the foundation).


If it matters, what I'm thinking of adding is something like these clips from an installation manual (EG: Mustee Utilatwin 22c):

Mustee utilatwin 22c

Aside from not knowing where an acceptable place would be to tap into the drain, I also don't see anything in the install manual (for this particular sink) that indicates a drain height.

drain connection

So, any particular guidelines on where in a drain setup like this it would be acceptable to add another drain connection?

Any experience indicating how high from the floor I should expect to make the drain connection at the sink (assuming there is anything approaching typical height for utility sinks, anything I can use to inform a purchase)?

  • which of those pipes are waste pipes ans which are vents?
    – Jasen
    Commented Jan 24, 2021 at 8:47
  • what's that rectangle thing in the corner that looks like an HVAC register?
    – dandavis
    Commented Jan 24, 2021 at 11:07
  • The level at which the exit of the P-trap is may be lower then the height of the drain pipe you want to tie into. It needs to above it.
    – Alaska Man
    Commented Jan 24, 2021 at 19:46
  • Haha, the rectangle thing is a insect sticky trap! Understandable though... @Jansen, I'm guessing they are both drains. The one on the right angles off towards the kitchen sink area, and the one on the left is in the vicinity of the dishwasher. @ AlaskaMan, that's kinda what I was figuring. Alternatively maybe I can go with a shallower basin tub, or a kitchen sink to get the trap higher.
    – renesis
    Commented Jan 24, 2021 at 22:22
  • -EDIT to previous comment: Realized my comment about the drain vs. vent doesn't make any sense. DW drains to sink trap. So pipe on the left is probably vent.
    – renesis
    Commented Jan 24, 2021 at 22:57

2 Answers 2


According to the specifications, the legs on the 22C and 24C are both approximately 18" long.

sink dimensions

You coulld probably put this sink in the location you want with a setup as shown below:

enter image description here

You will need to shorten some of the supplied drain assembly pipes so the p-trap is as high up as can be. The part in green is an optional air admittance valve and sanitary tee.

This should work because the pipe from the trap only needs to be sloped at the minimum 1/4" per foot while the main line looks to slope significantly more than that. The point at which the two pipes intersect is where you can use a reducing wye to connect them. The main pipe is large enough that it should suffice as a wet vent. The length of pipe that will span the distance between the trap and the wye connection is the trap arm and if this length is greater than 6', you will need the air admittance valve (it actually wouldn't hurt to use it anyway, unless they are illegal in your jurisdiction).

To get a rough idea of where the connection to the main line will be located you need to know the vertical height of the pipe that exits the p-trap. Find the point at which the middle of the 3" main waste pipe also has this vertical height, then mark a point at least an inch or two past that (to account for the 1/4" per foot drop in height the arm will make in this distance) then measure the horizontal distance that would be the length of the trap arm.

  • @renesis If you needed more tie-in elevation wiggle room, and your physical statures allowed, you could build a platform or add leg extensions.
    – coderjohn
    Commented Sep 4, 2021 at 17:13

To keep other gray water from backing up into the laundry tray, the waste line from the tray needs to be tied in at a higher elevation than the height of the J bend coming from the sink.

There are gray water pumps, and even pumps specifically for laundry trays so the water can be pushed up and into a connection at a higher elevation to eliminate the potential for a backup.

  • How high up on a waste line should the tie-in be? Or maybe better, what goes into calculating how high up the optimum tie-in point should be? For example, does the elevation of the street sewer line matter (perhaps because of the delta elevation to the house's main sewer line)? Or, a 5-year flood plain elevation, etc.
    – coderjohn
    Commented Sep 8, 2021 at 1:15
  • If it were me it would be higher than the lowest tie in that is already in place. For example the 3" line on the left side of the picture that drops into the horizontal 3" line that goes left to right in the picture. That way if the line gets backed up, the sewerage has another place to go rather than the sink which would otherwise be the lowest tie in. Also if for any other reason, if the line did back up, it would have to back up high enough enter the drain line for the sink. I was thinking maybe as much as 4 feet.
    – Jack
    Commented Sep 8, 2021 at 4:31

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