Ohh you mean the remaining water after distillation.
That water contains all the ions, organic materials and heavy metals that you removed from the distillate.
The easiest and most cost efficient method to re-use this water would be to...distillate it again...
But this will damage your system as it is likely to form deposits and corrosion. Plus,up to a certain concentration some ions will travel in the steam and end up contaminating your distillate.
You could also look into ions, metals and organic compounds capturing resins. But those are costly, have a fixed capacity and cannot be reused unless generating some wastewater again.
Honestly I would try to reduce the amount of waste water generated instead by doing a harsher distillation cycle and increasing maintenance on the equipment to ensure it is functioning at optimal conditions.