I have my HVAC units in the basement and the evaporator drainage goes into a small sump for each unit that pumps up into a drain. It sounds like your sump is processing more water than can be attributed to A/C condensate (unless you have a big house and it's really humid) though so this probably isn't the case but just a thought. Is there anything else in the house that might drain there? I guess I'm steering the opposite direction from the other posters in thinking that it's not coming from the ground.

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1983 M-B 240D-Gone too.
1976 M-B 300D-Departed.

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