Yes water goes eventually back into circulation but that does not help in the place where the system is already at it's limit

The contaminants consist of dissolved solids and minerals that were in the incoming water, plus additives such as anti-scalers, corrosion inhibiters, and antibacterials.

If you pump water out of one watershed into another, perhaps via evaporation and wind transport, then you better expect the downstream users, deprived of their water, to complain.

For example, the upstream users of water from the Colorado use so much that Colorado River Delta is nearly always dry. Or read about the California water wars.

Further, increased competition for surface water raises prices, which encourages additional aquifer extraction.