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Bwildly 09-08-2009 11:04 AM

Concrete basment floor drain
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Hello, here I have a picture of my floor drain in my laundry room. It is concrete all the way down to where the water is standing and that is where the actual pipe is. I noticed that about mid way up there are 3 holes which I can stick my pointer finger in and feel mud. My questions are how did these holes get there? Is this a big problem? Could I put a ballon down there and then rags on top of the ballon and patch these holes myself? And if so what kind of concrete would you use in this kind of problem? Thanks in advance for any help.

glennjanie 09-08-2009 04:05 PM

Hello BWildly:
Yes, your method will work just fine. There is no reason for the holes and, being open to mud shows that they need to be sealed up. Clean the holes as deep as you can and fill them with some mortar mix from Sackrete or Quickrete.

Nestor_Kelebay 09-08-2009 08:13 PM

Please don't fill up those holes.

Those holes lead to the weeping tiles around the perimeter of your house's basement foundation.

Here's how it works:

Every house has a big drain pipe that goes from just below the basement floor to just above the roof shingles called a "Vent stack". All the drains in the house will typically connect to that vent stack before it goes under the concrete basement floor. Similarily, all of the vent piping in the house will connect to the top of that vent stack before it goes through the roof to minimize the number of roof penetrations, and hence potential leakage sites.

Once that vent stack goes under your basement concrete floor, it turns and runs at a shallow downward angle to the city sewer pipe buried under the middle of the street you live on. That shallow downward sloping pipe is called the "main drain line" from your house.

Buried around the perimeter of your house's foundation are perforated pipes called "weeping tiles". The job of the weeping tiles is to allow excess ground water in the ground around (and under) your house to drain away via the weeping tiles. Those weeping tiles connect to the holes you can stick your fingers into mid way down your "CATCH BASIN" or "FLOOR DRAIN". By allowing the excess ground water around your foundation to drain away via the weeping tiles, that eliminates the hydrostatic pressure which would otherwise drive that water to want to leak into your basement through the concrete walls.

At the bottom of your catch basin, there will be a P-trap and then a pipe that connects that P-trap to the main drain line from your house. So, when there's a heavy rain and water accumulates in the ground around your house, it drains into the weeping tiles near the bottom of the foundation. Then it runs toward your basement floor drain and comes out one of those holes (with mud in it), and then flows through the p-trap at the bottom of the catch basin (aka: basement floor drain) and follows a pipe buried under your basement floor to the main drain line from your house.

The reason why people's basements often flood after a real heavy rain is because the main drain line from their house is partially clogged up. In that case the water coming in from the weeping tiles can't flow past the clogged drain fast enough, and the water ends up backing up the floor drain.

Don't plug the holes in the sides of the catch basin. They are what allow the excess ground water around your house's foundation to drain harmlessly away.

Bwildly 09-10-2009 05:33 AM

More Detail
Thanks for your very detailed answer to my question! I want to update some things to make sure these are for that purpose. It rained yesterday kinda hard so I went and looked down the drain and I did not see any water come out of them. May not rained enough though. I can stick my pointer finger to the knuckle in the holes and when I wiggle my finger it is mud all the way around. should I be able to feel something else besides mud in there? also these holes are not visable the way the drain was poured, the only way I found out they were there is because my floor drain has been rising while doing laundry to the level where those holes are and when I shined my light down there I say the water go in there. will this eventually erode the soil under there? just thought I would update you with a little more information to double check these are for weeping tiles. Thanks again.

Quattro 09-10-2009 07:22 AM

Not all homes have perimeter tile. Mine doesn't. I'm skeptical about the holes...I think they are probably just areas where large aggregate in the concrete has washed out. Said chunks may still be in your drain if they never made it to the main (4" underground pipe), causing a slow drain during laundry.

Nestor_Kelebay 09-10-2009 09:07 PM


You probably wouldn't have seen water coming in those holes during a heavy rain storm because it takes time for the rain water to permeate down into the soil to the depth of your weeping tiles. If the water level in your floor drain is below those holes, then check every day after it rains to see if the concrete below the holes but above the water level in the catch basin is wet. That wetness will be water seeping in from the weeping tiles.

I wouldn't be concerned about not beng able to feel a pipe around those holes. Nowadays weeping tiles consist of plastic piping with tiny holes in it. Years ago, it consisted of short (12 inch long or so) pieces of concrete pipe, and the pipes were just laid together end to end, and often not carefully so that you could have gaps between the pipe sections. But, that was good enough to provide a path for excess ground water to drain away by, and thousands of houses were built that way and continue to stand.

Here, let's analyze it this way.
You have holes and you don't know what they're for.
Your house is every bit of 40 years old.
Those holes haven't caused any problem so far.
Why plug them now and risk creating a problem.
So, the logical thing to do is leave them be.
Logic prevails. I win.

PS: The fact that the water level rises significantly in your catch basin when your washing machine spins suggests that the main drain line from your house is partially clogged. I'd say you're better off diverting your attention to having the main drain line from your house cleared than plugging up those holes.

Talk to a plumber. I expect he'll agree with me.

Quattro: The weeping tiles around a house's foundation serve an important purpose. Without them the hydrostatic pressure of the water around the foundation would cause water to want to leak into the foundation. By using weeping tiles to allow excess ground water to drain away, you prevent that from happening.

There are very probably houses that don't have weeping tiles around their basement footings, but I wouldn't call them "well built" houses. If you don't have weeping tiles around your foundation footing, then you probably don't even have insulation on the exterior of your foundation, and that's a recipe for problems. If there's no weeping tiles then the hydrostatic pressure of the water in the ground causes that water to want to seep into your concrete basement walls.

Now, what happens in winter when those same concrete walls are exposed to -40 degree C weather above ground? The concrete looses heat to the atmosphere and the whole concrete foundation gets freezing cold. If there's water in that concrete wall, then it's most likely going to be at the exterior surface, and freezing of that concrete will cause spalling of the concrete wall. That's where the pressure of the ice inside the concrete is so great that it cause the concrete at the exterior surface of the wall to break off in "chips". The more concrete breaks off like this, the more porous and permeable the concrete becomes and the more ground water can penetrate into that wall. So, lack of weeping tiles results in a problem that can best be described as a snowball getting bigger as it rolls downhill.

Nestor_Kelebay 09-12-2009 09:54 PM

Here ya go, Bwildly. A picture of the piping of your floor drain:

Now, notice that in the picture IT IS RAINING.

The rain percolates down through the ground to the bottom of the basement wall. There's weeping tile resting on the same concrete footing that the basement wall sits on.
The weeping tiles carry the water to a catch basin.(and that is a stupid looking catch basin)
(It'd be better to show that catch basin as rough concrete about the same diameter as the house's main drain line with a p-trap on the bottom. They've got it looking like a barrel with some kind of pipe on the bottom.)
There's a p-trap at the bottom of the catch basin, and then a pipe from that p-trap that connects to the main drain line from the house.

That pipe going up to the basement floor from the main drain line is supposed to be the vent stack.

The way they've got that drawn is kinda stupid. The vent stack should go below the basement floor, and then turn and go to the city sewer at a shallow downward angle. They've got it looking like the drain pipe from the catch basin flows at a shallow angle down to the sewer system and the vent stack connects to it. That's wrong. The vent stack turns under the basement floor and becomes the main drain line. The drain pipe from the catch basin connects to the main drain line somewhere under your basement floor.

You'd think that the City of Winnipeg would have run that drawing past a plumbing inspector just to check if there are any dumb things in it that need to be redrawn. Obviously they didn't.

Also, your house will have EITHER a sump pit with a sump pump OR a catch basin (aka: floor drain), not both. Both are shown in the diagram only because houses are built with both kinds of systems. Prior to 1990 in Winnipeg, houses with sump pits could have the sump pump pumping water directly into the house's drain piping so the water would join the water flow from toilets and sinks in the house.

Cuch 11-22-2009 09:22 AM

Floor drain with weep holes (back-up problem)
Hello Nestor,

I have the same problem as described in this post.

I have a sump pit (which is functioning properly) and a floor drain (3" - with holes about 1-1/2" down around the perimeter of the pipe).

Like the previous poster, when I run my laundry or empty a bathtub, etc. the water level rises in the floor drain. Also, once in a while I get some sewage backed up (paper, etc.) in the floor drain.

I installed a check valve in the drain a few years ago, and when the tub is emptied, the check valve "floats" to the top of the drain and seals it. The problem is that I also think that the holes are letting the water seep from the drain to under my slab.

I want to fix this problem, and eliminate the back-up (not to mention having sewer water draining under my basement slab). I am thinking about buying a cheap camera to see if I can find the problem.

Are there any other "tests" you can suggest before I go this route or cut into my floor? I don't mind spending the money on the camera and fixing it myself. I haven't had much luck with contractors doing quality work in my area.

The floor drain is less than 2' from where the main pipe is under the slab.

My biggest fear is that my drain is lower than my main pipe and this could be causing my problem. Does this even sound possible?

I apreciate you taking the time to read this and your advice.


- Cuch

Cuch 11-22-2009 01:35 PM

Thank you very much for the quick reply and your time Nestor. I tried to PM you, but forum rules say I have to haev 5 posts first (I'm sure I will hit that soon enough :D)

Thanks for the advice. I guess I am better off to have someone come and clean the main line first.

I am assuming this should involve something more than a "snake". The last time I had a sewer guy here, he simply snaked the main line (all the way to the street), found no obstruction, charged me about $150 and left me with the same problem. Is there some type of tool that is the same diameter as the pipe, that they should be using to clean the entire line?

BTW - It makes total sense that kitchen drain food wastes could be causing the problem, but my kitchen drain is almost at the point where the main line exits the house. I have a cleanout in the floor at that point and I have removed the cap and can see water flowing through the line freely when I empty the tub.

Thanks again for your help Nestor.

I really appreciate the advice.

Cuch 11-22-2009 06:57 PM

Thanks again Nestor.

I really don't want to bug you, but you are the only person I have ever seen provide an answer for the "holes" in a floor drain.

Here is what I *think* is going on with my problem.

My floor drain has holes in the perimeter that are supposed to relieve hydrostatic pressure from beneath the slab and let excess groundwater flow out to the city sewer. (See "Normal" image). I think this is a good thing.

When a large amount of water is released (tub, laundry, etc.), the water completely fills the floor drain pipe to the same level of where the water in the main pipe "crests". (See "Overflow" image - sorry water levels not exact).

When the large flow subsides, my drain returns to "normal", although sometimes with left over sewage still in the floor drain. (This might be a result of flushing the same time that the laundry is running?)

I "think" my drain might be too low as it is less than 2 feet from where the main pipe enters the floor.

I tested by filling my bathtub, then running all my taps for 20 minutes. I flushed the toilet multiple times with some paper it and then I released the bath water.

My drain float plug stayed sealed to to the top of the drain the entire time the tub was draining. I removed the cleanout cap near where the main line exits the house and could see the water flowing freely out to the city sewer, so I am assuming there is no back-up.

One last question: Is there any way to tell exactly how deep my main pipe is at the spot where the floor drain connects to it, without digging it up?

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