Is it not tanked or does the water run into the garage & down into the pit?
When I dug out for the foundations.
The bottom of the pit excavation, was some 3 feet down into the water table clay.
I made a double thickness membrane, of 12' wide h/d builder's polythene. All that was available to me, almost 50yrs ago.....
The water seeps in occasionally, during very wet weather.
Sometimes, 3 times a year.
Sometimes, not at all, for 3 years.....