Cats are very good at wasting very little water in their urine, which is why it is so concentrated and smelly. The downside to that is that is means minerals and such get bunched together which can cause kidney blockages. If this gets your cat to drink more water (assuming it is not goy slop water with chlorine and fluoride) then $90 is a very small price to pay to get some more good quality years for your loved one.
well put thanks
Also, dry food is good to have around as a backup but if you can afford mostly using wet food that helps too. They get extra water without drinking directly.
Cats can also be odd about water placement. Unless they are used to it they don't like their main water to be near their food. That's why they tend to always want to drink your water or water out of a plant with standing water in the base.