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qoncept 07-12-2010 01:31 PM

Adding a basement bathroom with sewage ejector pump
I obviously realized when we bought our house that there wasn't a bathroom in the basement, but what didn't occur to me is that the sewage line comes in to the basement about 2 feet up the wall instead of through the floor. Now that I want to add a bathroom, I'm not totally sure what I want to do. The house was originally built in 1981 with a septic tank, but at some point was connected to the city sewer utility. I would like to just rerun to the sewage main and stub the floor for plumbing, but that doesn't fit the budget.

I've seen Lowes and Menards have floor model basin/pump combos that you can mount a toilet on and plumb a sink/shower to. But there isn't a lot of headroom in the basement and I'd just as soon have it under the floor. I'm not totally sure what all that entails, but I want to lay out what I think happens and hopefully someone can tell me where I'm wrong.

I'm picturing cutting a 24" square hole in the floor, dropping a basin like this with an ejector pump like this in, stubbing up an inlet and outlet. I'm not sure at that point if I would want to fill the hole with concrete (wouldn't make pump maintenance much fun would it?) or cover it some way. And then I'm further confused -- that'd be fine for just a toilet, but how do I plumb a sink and shower?

Edit: I forgot -- we have a floor drain that's currently tiled to the sump pump. I'd like to plumb it to this instead. Also, I realize now I hadn't even considered vents. Do I need any?

dave53 07-13-2010 08:15 AM

Routing the bathroom plumbing to the pipe from the floor drain is probably not the thing to do. The sump pump that you mention is probably not a sewage pump. If the sump also collects water from the foundation drain, it's definitely out of the question, since this is a ground water system.

Your original idea is sound. A toilet requires 3" pipe, routed below the floor to the sump. The sink and shower would be wyed into this same pipe, in most cases. A vent is required, but the floor drain should have one; otherwise it could not have a trap that stays wet. If the floor drain has no vent and no trap, it would make sense that it routes to a ground water sump - there is no sewer gas to contend with.

If routing a vent to the roof is not possible, an air admittance valve might be acceptable, or perhaps a vent routed through the rim joist might be acceptable.

These days, routing a groundwater pump to a city sewer is a no-no, but many years ago it was common.

qoncept 07-13-2010 08:21 AM

I think I didn't say that very clearly -- I meant I'd rather have the floor drain plumbed to the new ejector system instead of the sump well.

It looks like this means I'm going to have to break up the concrete under the shower and toilet as well as for the sewage basin. Is that right?

LateralConcepts 07-13-2010 09:07 AM

I would make sure you get a quality pump and basin. After going through all of that work to open up the floor you'll want something that will give you worry free performance. Stick with brand name pump systems. i.e Liberty, Zoeller, etc. Liberty makes excellent pump and basin systems complete with everything you need. Do your shopping at a local wholesale plumbing supply, not the big box stores. The guys at the counter will be far more knowledgeable about what you're trying to accomplish. They'll also have sizing charts based on how much lift you need, fixture counts, etc.

You will not want to cover up the basin with concrete, tile, or anything else. I needs to remain accessible for servicing.

As someone else mentioned, you'll need at least 3" line under the slab for the toilet which will run into the side of the basin. The shower and sink would wye into that 3" line. 2"(shower) and 1 1/2" (lav). The top of the basin will have a 2" discharge and a 2" vent. The discharge will need a ball valve as well as a check valve. The vent side will also need a union for servicing.

qoncept 07-13-2010 09:14 AM

Got it.
1) What DO I cover the basin with? I'm picturing a hole in the floor with a big ugly basin and surrounded by dirt and gravel. I might be able to hide it behind a wall and still be accessible from the other side, but I haven't thought that far yet.

2) What's the ball valve for? I noticed some of the complete systems included it, some didn't. The check valve makes sense, but I don't have a ball valve anywhere else?

LateralConcepts 07-13-2010 09:48 AM

You can re-patch it with concrete but just up to the edge of the lid. The lid will sit flush with the floor (depending on the system you choose, it may be somewhat convex shaped actually). Hiding it behind a wall or in a closet is fine. Again, just needs to be accessible.

The ball valve (above the check valve) simply helps for servicing. If you ever have to pull the pump, you would shut the ball valve off to keep any standing water in the ejection line from draining when you pull it apart. A check valve will have either compression unions on each side or fernco type rubber fittings on each side with clamps. You would pull it apart by loosening the bottom of the check valve.

Another thing to consider is a dedicated circuit to plug the pump in as you will not be able to use an extension cord.

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