I am installing a sewage ejector pit and pump in basement, hole is dug and I piped the inlet pvc for the toilet and sink. I did not have time to backfill or concrete.

The next morning I woke up to find after a night of rain the basin floating in groundwater. The septic tank is right next to my sump pump.

If I backfill and concrete the sewage basin and pump in, will the excessive ground water be a problem later?


We can presume that the basin is watertight (both out and in). The only real concern, then, is whether the boyancy of the air in the empty tank will overpower the weight of your concrete (or the mechanical connection between the concrete and the basin).

If those aren't a concern, all should be fine. I imagine that the basin has edges and depressions that will anchor it well in the concrete.

  • I would use hydraulic cement to seal a pit like this but agree if sealed and anchored it should be fine+
    – Ed Beal
    Dec 26 '18 at 2:09

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