I have a cleanup pipe in my basement that has access through a hole in the floor. The top of the clean pipe is about 6" below floor level. It seems that the bottom of the hole is just dirt.

The hole is covered by a irrigation cover that is usually found in a lawn. I suspect the builder showed up with the concrete to pour the floor and realized that they clean out pipe was below floor level. Rather than hold pouring the floor to extend the pipe, they improvised.

During prolonged rains (greater than a couple of days), the water rises out of this hole and onto the floor. However, the hole is always damp.

There is also a musty smell.

It is a walkout basement so there is not a lot of water pressure on the floor. This hole is on the opposite wall of the walkout. So if the water continues to come in after the fix, then the next step will be to add tile on the outside of the house. BUT, that will be costly as I will have to breakup a driveway.

With the goal of preventing water from coming into the house and getting rid of the musty smell I am inclined to extend the clean out pipe to floor level (or above), then fill the hole with cement. To protect the pipe from being kicked I will build some shelves in this corner.

Here are my questions:

  1. Is this a good idea? Or is there something else I should consider?

  2. Any tips on extending the clean out pipe? For instance, is the standard size sufficient for cleaning out when it is extended, or should I also expand out to a larger pipe so the access is easier.

  3. Is there a particular cement or technique that will be less likely to allow water to seep up through the crack where the new cement meets the old cement? And where the new cement meets the pipe?

[Edit] I found out this is a backwater valve that prevents sewer water from backing into my house. There is a riser kit for this valve, but this value is 15 years old and the riser kit for my old backwater value is not longer available. The company uses the same part numbers for the new and old parts (even tho they are not compatible, so it will be difficult to find an old riser kit).

hole in floor with clean out pipe

  • Someone must make "indoor manholes" for covering this sort of access pit securely while till allowing maintenance access ... (I have something similar, with a few boards over it and a plastic mat over them. But mine's never had any noticable scent. That may or may not be because I'm runnong a dehumidifier.)
    – keshlam
    Commented Jan 1, 2016 at 3:36
  • @keshlam, they do, but they are installed at the time of construction/remodeling and they are huge in comparison (about 2 ft by 3 ft), sealed for radon, accessible, and allows under slab water a way out for the built in pump it has.
    – Jack
    Commented Jan 1, 2016 at 16:07
  • Does this access have a cover? Also building a wall over a place that intermittently gets wet is asking for mold under the wall when closed back up.
    – Jack
    Commented Jan 1, 2016 at 16:16
  • 1
    This has a cover that does not seal and is not intended to seal. In the picture you can see the seat for the cover. Once I seal it the hole with cement I will leave the wall open until I am confident it is actually sealed. Commented Jan 1, 2016 at 20:37

1 Answer 1


Water is very sneaky. It will always find the path of least resistance. To fix this problem you need to first find the actual source. You may have exterior sewage draining back into your house. A licensed plumber can use a dye in different areas and that dye will show up in your clean out pipe. If it does then you know where it came from and where to begin fixing the problem. If it does not, then you know that it is simply water from outside. Remember, that pipe was put there for a reason. Sealing it may cause more problems in the long run.

  • 3
    Regarding where the water is coming from: It is just rising in the hole and only does so during a prolonged rain, so I reasonably confident that it is rain water. Even during the longest of rains it may only split a gallon or two on the floor. Regarding what the pipe is for: It is the drain pipe for a bathroom (shower, toilet, sink). This is a standard clean out access for that pipe. I am not intending to disable the ability to clean it out. Commented Jan 1, 2016 at 5:00

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