Bathroom remodel - interesting find under pre-fab shower

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R

rhwimmers

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Doing a full remodel in our BASEMENT bathroom - so this is on concrete floor. We removed the plastic pre-fab shower and this is what was under it:

https://photos.app.goo.gl/4XBd7ygDvePs9UtUA
There's a washcloth in the drain just to stop the odor - but why is there this huge "pit"? It looks like there was a black plastic "surround" in it but its cracked and buckled and there is water in it. I shop vac'd it out but after a few minutes it just fills back up with water. The water is not sewage (doesn't smell at least). The drain just goes through the concrete into our sump pump room where we have both a grinder sump and regular sump. I can get better pics if needed? We're going to do a full tile floor/wall/ceiling tile shower, but would hate to just cover the hole with hardibacker with standing water? Seems so strange...I only filled a small shop vac a few times before stopping, I can keep sucking water if needbe if that's whats needed? So strange.
 
No great solutions to the water intrusion. Probably, after fixing the plumbing w/p-trap and new drain, and wrapping all the piping with foam wrap to prevent concrete from contact with any pipe, then pouring concrete.
May be simplest to have a plumbing contractor do this.
 
Last edited:
Oh, yes sorry, I put the rag there just during construction.
So...Just leave it as is??? Cover the whole hole with hardibacker, cut hole out for the drain and live knowing theres just a small pit of endless water?! In the room next to this bathroom is our HVAC room and it also has a floor drain that goes to the sump room SEEMS like this is "lower" than this bathroom but very possible they are the same elevation.
 
That’s the box they install for a tub or shower so a P trap can be precisely positioned while installing the shower or tub.

It appears no one installed a ptrap and no one sealed the slab box after connecting the shower without a ptrap.

Amateur work at its finest.
 
Yeah I thought it was odd there was no ptrap - we've definitely had nasty smells from the shower so we'd normally just keep a towel over it (this shower RARELY is used).
SO...what would you recommend the fix be? Install a P-trap and fill hole with concrete? Should I keep shop vac'ng water out and see if it ever stops?
 
If you’re going to install another shower then it needs a ptrap. The hole would then be capped with a 2” layer of cement or poured tar.

I can’t give you advice about ground water.
 
It looks like that 45 degree fitting pulled apart some. If that's where the shower drain is going to be at maybe you should cut
it before the 45 and put a coupling on and then your new p-trap. I wouldn't trust that piping.
 
Yeah i'll likely redo the plumbing as the drain wont be exactly the same but do have a lot of flexibility as were just doing all tile. My main hang up/concern now is that ground water situation!
 
If you take the plumbers advice here and redo this drain system properly, ensuring there are no leaks in the drain piping, and with the proper P-trap, and fill this in with concrete you will prevent groundwater from affecting this particular spot.

Of course all you’re doing is pushing the ground water to another location. if your basement was built properly the slab would have been poured over a sand or other base, and there would be a full and proper floor drain system going to either daylight or a sump. Done properly that is supposed to take care of water underneath the slab, which is why they have those systems in the first place.

I don’t know what the current code is for where you are or what the standard protocols are (which are not always correct by the way), but from where I came from in the upper Midwest, surrounding the footing of the foundation was a complete drain system with numerous penetrations through the footings, which then tied in to the under slab drain system in the basement, and all flowed to the sump. So, if you had ground water around your foundation or you had water spillage in your basement it all went to the sump and of course was then pumped out. My town had a separate storm drain system and that’s where the sump connected, this was different than the sanitary sewer.

Your ground water situation might be something as simple as bad grading around the foundation or gutters not draining away from the foundation and water getting underneath the footings and then the slab. It also might be some thing like a high water table and that may be more of a challenge and shame on the builder for not doing the proper soils testing before putting in the foundation.

There was another wacky thing that some of the builders did to some of the lots in my extremely large subdivision in Michigan. on lots that we’re “boggy”, or had a high water table and thus were not buildable in their natural state. They had water well drillers come in, and drill multiple water wells, temporarily, and have the series of pumps going for weeks at a time in order to dry out the lot and lower the water table in that area. That’s one way to deal with a situation with ground water…
 
Very familiar with the indoor "french drain" systems as we had to install one to our last tri-level house- THAT was expensive and a huge pain! I am fairly certain there is a perimeter drain system in this basement as the sump pump is always working hard after a good rain.
This "pit" is only a few feet from the foundation wall under our garage. I think if there is indeed a perimeter drain then filling this hole with concrete should just push that water back towards the perimeter and then that ground water will go where it should (ending in the sump). If not..well I dont know then lol. We've never had any issues with this ground water coming up into the shower and this water has just been sitting under the shower basin since the 90s when the house was built. Doesnt smell bad or create issues so I GUESS I can just cover it up with hardibacker - just feels strange doing so.
 
Back to this project again and another question - we got a replacement pre-fab shower and (of course) the drain isn't anywhere in the current hole. I circled it in green and wondered how hard it would be to knock out this concrete enough to get a proper Ptrap and angle so the drain is where the green circle is. Not sure where to start or what tools I would need to do so or how hard that would be?
Here are a couple pics
https://photos.app.goo.gl/uTaJM1pqkWiGzwNK6
Note - I did use a larger shopvac and empty this hole about 25 gallons worth and the water comes back and fills to the same level as before after just a few minutes. So I do think its just ground water and likely just an area where its not graded properly to divert that water to the perimeter drain system which then empties to the sump. I'm just going to leave it alone as I dont think filling it with concrete is really going to achieve anything.

Thanks!
 
Well it will only be covered by a pre-fab shower, as it has been since '93 when the house was build I presume. So would I fill it with sand for a few inches and then mix concrete and pour on top of the sand and just needing to leave room under the PVC for the ptrap I need to add etc?
 
No, you get your rough-in plumbing done, P-trap connected to the drain and a stub up to connect to the shower. Then fill the hole with sand up to 2 inches or so from the existing surrounding "floor" level, imbedding the drain piping and P-trap in the sand. Then place a concrete cap over the sand.
 
Oh, so all the new plumbing I put in is going to be burried in sand with concrete on top? And in regards to the new drain location, any advice on if/how I will break that concrete so I can get the drain moved to that area? Lastly, i'm not sure what you mean by "a stub up to connect to the shower"?
Thanks!
 
A sledgehammer if you're young or rent an electric jackhammer. The big box stores have them. Break the concrete above the drain line to a point where you can pipe it to the new location of the drain. The concrete should only be 4" thick or so. Hit the concrete to each side of the drain line, not directly over it. Start at the hole and work your way down the drain line. It looks like you basically just need to shorten the drain line some without any major turns, so this may be pretty easy. You will want to avoid any short radius elbows if there is a large change in drain line direction.

A "stub up" is a piece of pipe that gets connected to the shower drain hub. And yes, all the plumbing will be buried in the sand and capped with concrete. You will want to wrap the stub up with a piece of foam or even bubble wrap that can be cut out to allow space for the shower hub to fit over the pipe.

But here's the biggest issue you probably have. Your photo doesn't show any vent, and as this shower was installed without a trap, I suspect there is no vent since the vent's purpose is to keep a P-trap from being siphoned. No P-trap, no vent! That means you will likely have to get a vent line into your new shower piping somehow. You can use an AVV (air admittance valve) if you do not have a path to your attic for a vent line or to the outside of your house. More investigation of the drain line under the slab is in order.
 
So I was thinking I would only need to break the concrete to the "top left" of the current square hole - the PVC is already angled the right direction so I thought just breaking the concrete another 6" or so and then id cut the PVC right after the first elbow, put p-trap here, and then to the stub up/connection to shower drain. This drain goes straight to the grinder sump in the basement about 40' away. I dont know if its "vented" or not but the PVC just runs straight up and out to our sewer. Not sure if that helps?
 
Oh OK, I just assumed the drain was going the other way to be more centered in the shower. So, your job will be easier in that respect.

The most lenient plumbing codes only allows a 2" horizontal drain line to go 8 feet before it is vented, and some even have a 5-foot maximum between a P-trap and a vent.

As I said, the vent in a drain line is to prevent the flow of water from siphoning out the water in the trap, and 40 feet is a pretty long run. Are there any other drains flowing into that 40-foot line? You could install a wye in place of the existing 45 elbow and break up more concrete continuing straight to the wall that the drain line is pointing. You would have cut the bottom plate of that wall and install the vent up that wall. I'm not sure what's on the other side of that wall, but you could install an AVV in that wall as a vent for the shower.

Amazon.com: Studor 20380 Recessed Air Admittance Valve Box and Grill : Patio, Lawn & Garden

More piping and concrete work, and added wall work, but the right way to do it.

If this is the only line on that 40-foot drain line, you could theoretically not vent the line (which is against all codes), and then run water SLOWLY in the shower after each use to make sure the P-trap is full. But any house inspection in a future sale could find this unvented shower and then the cost to correct this issue would be substantial.
 
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