I wouldn't necessarily blame a water leak. The chlorine test might prove this, but depending on how long it takes to get to the pit it may dissapate before you can test it.

Two water meters, probably just a remote reader, and they get out of sync.

Here's an Idea, find the BBox (buffalo Box) which has the exterior valve.
Turn it off for a few hours and see if you still get water in the pit.

You can buy the wrench, or ask your water company if they will come by and turn it off, then back on later.

You could also have an old farm tile running through your house. If it was farm land a lot of drain tiles were laid. Then when they built the house, they don't care or might not have seen it and just cut through it.

Note that I have a similiar issue, during droughts, my sump runs regularly. Not every 7 or 8 minutes, but even in 88 when we had a terrible drought here it ran 10 or 12 times every day.

We haven't had any noticable ran in a week or two, and it is still running at least every hour.

But I know my neighbors back yard was a bad swamp before they "filled" it in.
I heard 6 or 8 18 wheel dumpsters of sand, before they put soil over it.
It still turns into a lake any time we get much rain.

__________________
KLK, MCSE

1990 500SL

I was always taught to respect my elders.
I don't have to respect too many people anymore.