I use it for home brew beer, I get a pretty clean start with RO water and then re-mineralise depending on the style of beer. If you found an ideal mixture of the salts you want, you can measure this out for your volume of water. The salts are items like calcium carbonate, bicarb soda etc mostly common household items.
Yeah, here’s a bit of a guide from the beer side and a little extract.
The more chloride, the more malt flavors shine. Enhances fullness and malt sweetness (thick mouthfeel). The more sulfate, the more hops bitterness shines. Produces a drier or crispier beer (thin mouthfeel). Link