If you want to make significantly better beer, you need to focus on water chemistry.
Beer is 90% to 95% water.
The first thing you need to do before you start messing with water chemistry is to get a base mineral profile of the water you’ll use to brew your beer.
You have three options to learn the mineral profile of your brewing water:
1) Ask your supplier for a report
2) Get it tested by a water testing company
3) Buy a kit and test it yourself
You will need numbers for the percentage of sodium, calcium, magnesium, sulfate, chloride, bicarbonate, and total alkalinity. It's also important to find out if your water supplier uses chlorine or chloramines for disinfection of the water.
In order to use any water for brewing, there is a steadfast rule - the water must be chlorine & chloramine free
Here are some great articles to get you started
Water adjustment can make the difference between a good beer and a great beer. BY JOHN PALMER