I'm attempting to install a new sump pump in my basement after having a few minor flooding incidents and addressing as much of the external causes as possible (gutters, etc). The pump is only used for dewatering the foundation soil; nothing else drains into it.

I live in Rochester NY, which does allow connecting sump pumps to sanitary lines, which is probably the most reasonable option. I could entertain discharging to the outside, but there's not much avenue for that, given the geography and how little land there is around my house.

The sump is located 2 feet to the right in the below picture; discharge tube isn't connected yet. Bottom of the discharge has a standard check valve.

I was wondering what is the correct way to tie the sump discharge into to the sewer stack, pictured below:

Sewer stack picture

Question 1: What would be the easiest place to tie in?

I was thinking of tying into the 2-inch pipe on the left of the picture using a 45 degree wye pointing to the right, given that it has the most pipe to work with and is probably the cleanest to work with. I would run the discharge pipe up the wall on the right, angle it on top of the sill you see at the top of the picture, behind the existing iron-cast pipe, and down next to the 2-inch pipe on the left.

Question 2: Do I need any sort of p-trap? The discharge line has a check valve at the bottom of it, so there should always be a significant amount of water (10 feet) in the discharge riser to prevent sewer gas leaking back.

Question 3: Does the horizontal run of the pipe need to be sloped?

Question 4: Do I need an air admittance valve at the top of the discharge? The large pipe at the top-right of the photo has an air admittance valve about 10 feet off the floor, and I believe the pipe I'm tying into has an AAV, 2 floors up.

Question 5: How much height do I need off of the wye from the 2-inch before I go horizontal? I was planning on cutting into the pipe in the middle just for convenience.

  • In my area, sump pumps aren't supposed to be tied into the sewers at all, so check your local codes. (We're supposed to discharge somewhere onto our own land.) – keshlam Sep 9 '14 at 21:16
  • @keshlam - "I live in Rochester NY, which does allow connecting sump pumps to sanitary lines" – antiduh Sep 9 '14 at 21:17
  • You should contact your local building department, as not many locations allow you connect sump pump discharge to the sanitary sewer system. In fact, a lot of places will fine you for doing so. Some places have storm sewer systems, which you are allowed to tie into. – Tester101 Sep 10 '14 at 13:44
  • @Tester101 - Thanks for looking out for me, but I've already looked into it. Rochester only has a single discharge system; sanitary and storm are one and the same. Plumbing code discourages sump discharge connections, but allows them. Unfortunately, because my property is so small, there is no place to discharge that wouldn't end up back in the house, or affecting someone else, or spewing all over the sidewalk and street. Half my property is uphill and is the exact source of the water I'm trying to remove. The other half is a 5-foot-wide sideyard. None-the-less, sump to sanitary is allowed. – antiduh Sep 10 '14 at 16:39

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