I am adding a pantry next to my kitchen and wanted to tie into the kitchen sink drain for the washing machine. The "T" for the sink is at 18" off the ground. The drain is going through two walls and turn 90 deg. I was wondering how much of an incline, pitch I need to give the drain a little "push" on it's way to the drain. I can put the washing machine drain at any height since it will be a new set-up. I do have to turn the wall at a 90 deg but am planning on using a 45 elbow with a two inch piece and another 45 elbow to transition to the drain.

The washing machine drain ( "S" trap and vent) is going to be approx six feet away from the transition and then another six feet to the kitchen drain. My question is how much pitch should I put between the "S" trap to the two 45 deg elbows and then from the 45 deg elbow to the kitchen sink " trap to the two 45 deg elbows and then from the 45 deg elbow to the kitchen sink "?

Can I go with a one inch pitch from the "S" outlet to the 45 deg elbows and then another inch from there to the 45 elbows to the kitchen sink "?

Can I go with a one inch pitch from the "? OR would I need more. Also I have a vent already there, next to where the "S" trap is going to be.

Hey racueto... Plumbing code requires 1/4" pitch per linear foot of drainage...so you would need appx. 3 inches of pitch on total run described.

What size pipe is your kitchen sink drain pipe...? I would prefer to see you pipe this drain individually as well as piping this 2" all the way to a 3" drain line in basement?? I would love to see cleanout at every change of direction and just prior to where you make your final connection into larger pipe (or kitchen sink...:( ).

The p-trap (not s-trap) should have a minimum 30 inch piece of pipe coming out the inlet of the trap (where washer hose connects into drain) and I like a 12 -18 inch piece between the outlet of trap to the tee fitting that heads off to vent (top of tee) and waste (bottom of tee) line. The vent should be a 1.5" vent. Most of this is actually code requirement and these numbers are for good reason. Good luck and let us know if you have any more questions.

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Since you said you wanted a little "push" for this line.

I would like to add that too much pitch is not good. Too much pitch and the water runs away too fast leaving anything in the water behind to clog pipes. Do the 1/4" per foot then go straight down if you have to.

Yes, sorry p-trap. The height of the outlet of the p-trap is going to be at 21" since the "T" for the kitchen is at 18". 1/4 for every linear foot of travel is three inches. 1.5" slope to the first bend and then another 1.5" slope to the kitchen sink "T"

I am going with 2" PVC for the drain and 1.5" PVC for the vent line. The area where I am hooking it into the kitchen sink is right before it goes into the wall. I can't run it through the walls as I would have about 3/4" of remaining stud if I run the drain through the wall. Did I also mention that this is a load bearing wall and is also an exterior wall. I also don't have a basement. A plumber came over and told me that this would be the way for me to go, strapped to the outside of the studs.

What I don't understand is the 30" and the 18" piece of pipe you are talking about. If I understand right, I need 30" from the top of the washing machine hookup to the inlet of the p trap and then 12 to 18 " from the outlet of the p-trap to the y-tee is where I need to hook up the vent line?

OK... If you must connect this into the sink drain.. I want to see you connect it lower then the kitchen sink drain. If you connect the washing machine higher then the sink, when washer drains you effectively cut off the vent to the kitchen sink drain... that is frowned on... ;)

Instead, if you connect the washing machine drain lower then the kitchen sink drain and you vent the washing machine all is good (both have vent above centerline of waste/p-trap).

The 30" requirement is simply the length of pipe required from the p-trap to the washing machine hose...I don't really care what height you start at...the drop into p-trap should be around 30".. the 18" I said..well...i..forget that...f you have a 2" p-trap and an 1.5" vent you can have the p-trap up to 5 feet away from your vent... no more. That means that you must transition to a vent via a TEE fiiting within 5 feet of the trap... walls, studs, whatever.. does not matter... 5 feet maximum before you transition to a waste/vent tee. Thereafter... do what you have suggested.. sounded good.

Thank you for post.. helps when I know... :) ALso, if finding this helpful, please RATE THE ANSWER by clicking on button below. NOTE--->>> ANy more questions... just fire away.. I am on nightly. Good luck

I have a double sink with a garbage disposal on one side and regular drain in the other. They both join together with a "Y and then into the wall to a "T". From this "T" the top side is connected to the vent line going up and the bottom is going into the slab. I barely have room and was wondering if I can tap in the washing machine drain right after the "Y" and before it goes into the "T"? The "T" is in the wall and the drywall is removed.

The setup I'm looking at doing is a "Y" (already there) from the double sink going into another "Y" into the "T" in the wall. I'm essentially connecting the washing machine drain at eh same level as the drain for the kitchen sink. The drain for the washing machine will have it's own vent about 12" after the p-trap

I would prefer that you connect it under the tee fitting as previously suggested.. I know it is a lot of work to do... BUT I can understand that you are looking for simplest way.. so up to you! Good luck.

I will do as suggested. I wouldn't want to really take any shortcuts and pay a heftier price later