Water Stain on Slab floor

Afternoon gents,

Yesterday I did an inspection on a new build (year old). Floor was the finished slab, and in two of the bathrooms there was staining around the plumbing penetrations. (This pic is from the bathtub in the master). Has anyone seen this before and could offer expertise on a route cause?


Mark Allen

Not much staining…maybe condensation from draining warm/hot water into the cooler concrete floor?..Just a thought.

Glad we just need to refer it out to the qualified plumber and let them figure it out. :smile:

P.S. It is nice to see you back after a year’s absence, Mark. Enjoy our forum!

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Thank you for the quick response and your input. This was one if the first homes I have done with a home with a finished slab as the floor. (Family with 6 kids all under 9 and three dogs so it made sense lol)


Maybe the concrete had been contaminated by something the plumber used around the drain that affected the way the floor took the finish / sealer.

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Check the tub waste shoe under the tub. Putty dries out over time and it looks like the stain is heading in that direction. Next culprits is the overflow gasket, those things may leak if the tub if filled too high. Next check all the slipnut fititing. You really only need to report the evidence of prior leak and not the cause. Now if you see an active leak that’s different.

My name is Larry. You can use it if you so desire. :smile:

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Looks more like concrete patch than a stain to me.


Jeff I agree with you it may have been boxed out for the trap plumbing then filled back in


That’s my thought as well.

Thank you everyone for the replies!


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Looks like patch to me as well, in addition they may have added or moved the location of the tub

As other have said the floor was cut out for the tub drain and poured back.

It doesn’t look like any concrete cut out that I’ve ever seen…maybe a sledge hammer…JMHO. :smile:

Possibly used a sledge hammer! Could have been having a bad day and needed to beat on something. We all get like that once in a while! :crazy_face:

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More common than most may think!

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