We just bought a new house and had a flood due to power outage. We gutted the basement and decided to water proof it. Got a new sump pump with we'll put in and installed a French drain.

After installation of the French drain, I noticed that the concrete is slightly darker/discolored (due to dampness I'm guessing) between the old concrete and the new around the perimeter of the basement.

I talked to the company that installed it and they told me it's normal and not a problem as long as water is not coming through. This happens because the new concrete can't fully seal and stick to the new concrete and we may have slight discoloration.

This happens after heavy rain and so far had no issue with water coming through. Our new pump works great but still worried about the discoloration. Is this normal after a French drain installation? Will I have a problem in the future if I cover the concrete with carpet or something?


Tried to call the company to see if it's normal. Apparently it is since they pour new concrete around the perimeter of the basement and the new concrete doesn't fully stick to the old concrete. Dampness might come in through the gap.

  • 3
    Discoloration/difference in colour is expected between new and old stuff. New concrete does not bind that well to old by itself but think there are sealers that should reduce .moisture coming though. New concrete takes about a month to fully cure/dry.
    – crip659
    Sep 9, 2022 at 15:23
  • Hello, thanks for the feedback. Would you recommend any particular sealers?
    – MB41
    Sep 10, 2022 at 23:35

1 Answer 1


New and old concrete look different, period. That, of itself, is not a problem.

You can try to artificially age the new concrete to be more similar-looking to the old concrete. The "different look" has nothing to do with whether or not it leaks. Artificial aging techniques - pile damp leaves on it, brush with damp used coffee grounds, throw some dirt on it. Or go the other way and try to acid-clean the old floor/walls.

Throw a coat of concrete paint on it if wanting all the same color (that might want you to clean the old stuff first, and will need the new stuff to be at least 30 days old, normally.)

If you carpet a basement floor that only doesn't flood when the power is on, you are just asking to remove moldy carpet in the future. Stick to ceramic tiles or paint unless your French Drain is actually one that does not need a sump pump to work. And don't store things that are ruined by water on or near the floor.

  • Hello, thanks for the feedback! My understanding is that the interior French drain is funneling the water from around the perimeter of the basement and into the sump pump well. So if the power is out, the sump pump will still back up. As for the discoloration, yeah that makes total sense. However there's still dampness color around the seem where the old and new concrete meet. My wife and I are looking into concrete staining as well to avoid moldy carpet.
    – MB41
    Sep 10, 2022 at 23:33

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