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I have a new bar sink in my basement. The only remaining jobs are to tie the pex lines into the main water lines and to connect the sink drain to the sewage pump. The part that has me a bit troubled is preferring to avoid opening the sewage basin, or drilling a new hole in the top. I noticed the basin has a vent pipe and was wondering if it would be permissible to connect the drain from the sink into the vent pipe using a wye fitting.

UPDATE: I went ahead and did it, and it has been working and properly pumping just fine.

enter image description here

--END UPDATE--

In the image below the pipe on the far left can be ignored, as it is for the sump pump. The pipe on the far right is the sewage pipe, and the pipe in the middle is the vent pipe.

enter image description here

If I were to do this, would it be to code? Or would it cause problems when eventually selling the house?

If not, is there a relatively simple alternative that wouldn't require a new hole in the sewage basin lid?

person0
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    That looks more like a sump pit that is meant to pump away groundwater, nothing to do with sewage or gray water (non-toilet waste water). – ratchet freak Feb 27 '23 at 17:28
  • My understanding is that there is one sump pump in the front, and the rear is the sewage pump. The sump pump is piped directly outside the home, but the sewage pump ties into the sewage drain lines above it. – person0 Feb 27 '23 at 18:07
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    You may be right. But interior sewage discharge pumps I've seen have been free standing, for ease of servicing & replacement. Exterior ones (called grinder pumps in some parts of the country) I've come across are in a buried concrete lined pit, sort of like a septic tank. – SteveSh Feb 27 '23 at 18:18
  • Oh, well, I was thinking this was a grinder pump, though admittedly, I've never heard it run that I can remember. I do know it is definitely tied into the sewage lines that other drains and toilets are tied into, where the one in the front is pumped directly outside. – person0 Feb 27 '23 at 18:34
  • I doubt it is a sewage pipe, it is too small for that, it should be at least 3 inch or preferably 4 inch pipe or even 6 inch – Ruskes Feb 28 '23 at 00:01
  • If a sewage pump. for the vent to work as a drain, it would need to work like a sump, sewage drains in till it is pumped out. More likely a sewage drain pipe is connected to the pump directly, so draining though the vent will only fill up the hole, with nothing being pumped out. – crip659 Feb 28 '23 at 00:46
  • If the two pipes are sewage outflow and vent, then your inflow to the sewage pit must be through the pit walls. You need to open the lid to determine exactly how things flow, from where to where, and how the pump works. You should not just pour water on top of everything through the vent pipe...*It might work* but you have to open the lid to make sure! If it is ok for your bar sink to pour in through the top, I don't see what's so hard about making another hole in the lid, it seems easier than fitting a wye to the vent! – jay613 Mar 01 '23 at 20:24
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    Another consideration: If the bar sink is not used frequently, you must ensure its trap remains full or else it will become the vent for this pit. – jay613 Mar 01 '23 at 20:25
  • @jay613 I was concerned about making another hole because I am concerned about getting a proper seal on it. – person0 Mar 01 '23 at 21:15
  • You've been around SE long enough to know how things work here, please make your "update" an answer. Also, do you know that this will meet code? You may still get dinged on this in your inspection or at sale time. – FreeMan Mar 06 '23 at 15:28
  • @FreeMan, I believed my update wouldn't constitute an appropriate answer because the simple fact that I did it and it works properly, doesn't technically address safety. Also, as you mentioned, it doesn't mean that it was done according to code (which doesn't bother me personally as long as it works properly). If even considering that, you think I should make it into an answer, I guess I will, but it is definitely non-authoritative. – person0 Mar 06 '23 at 16:13
  • I guess that, so long as neither you nor your heirs will ever sell the place, meeting code doesn't really matter... – FreeMan Mar 06 '23 at 16:40
  • @FreeMan, I appreciate the consideration. In my experience, when something doesn't meet code, it is a matter of what the buyer wants to care about. It may come down to some minor re-work if that ever comes up, but it was worth the risk for the positive value it brings to experiencing my home right now, and the minimal expense. Thanks. – person0 Mar 06 '23 at 17:15
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    Yes, what you did will probably work OK, irrespective of what the plumbing code says. The one problem I can see is the pump, when it discharges, could suck the water out of the P-trap under your new sink. That is, if it hasn't already been emptied due to the long run and drop of the drain pipe – SteveSh Mar 06 '23 at 17:17
  • @SteveSh, the drain is properly vented according to code at the source where the sink itself is. Should that reduce the chances of the water getting sucked out of the P-trap? – person0 Mar 06 '23 at 17:36
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    @person0 - That's the right thing to do, and should prevent the problem I was talking about. So now you have two vents into your sewage pump? One's the original, and a new one from the vent that was added as part of the sink install? – SteveSh Mar 06 '23 at 17:41

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On second thought, despite my earlier comments, it could be a sewage discharge pump that's installed in the floor.

The one house I had with a sewage pump had the pump free standing in a utility room at the lowest level of the house. Here's a couple of pictures of the installation:

enter image description here

enter image description here

Note that is says both the vent and discharge pipes are 2" diameter. The discharge pipe is the one wrapped with insulation. The sewage intake is the bigger 3" pipe on the lower left of the housing.

This plumbing arrangement is consistent with OP's setup.

SteveSh
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  • Yes, the basement plumbing with the 3" pipe feeds in below the concrete. That is my understanding. Thanks! – person0 Feb 28 '23 at 01:35
  • This doesn’t actually answer the question that was asked. – nobody Feb 28 '23 at 02:02
  • I know. But most of the comments had to do with whether this was a sewage pump or not. Until that could be established, the question was not relevant, in the sense that it would not be applicable to a standard sump pump. – SteveSh Feb 28 '23 at 02:49
  • This is an unusual use of a sewage pump. The most common is to pump out a basement bathroom, including a toilet that is *on the floor* and so the pit obviously needs to be under the floor. In the above situation, it appears to receive its contents from the floor above? Is that right? Meaning the ground floor also requires pumping? Or perhaps this pump is in a sub-basement? Or the lower half of a split level and the bathroom is in the upper half and the sewer pipe is even higher than that? At any rate it's not typical. – jay613 Mar 06 '23 at 15:05
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    @jay613 - I assume you're referencing my post & pictures? Yes, the pump is receiving effluent from the floor above it. And yes, the sewer pipe is higher than that. The house is down hill from the street, along which the waste water (sewage) pipe runs. So the effluent needs to be discharged higher than the basement floor in order to reach the elevation of the main sewer pipe. This is typical in many locations when the public sewer hi higher than the house's outfall. – SteveSh Mar 06 '23 at 15:26