I live in an area that has over 300ppm of disolved solids in my tap water. We used to use a Brita filter and it just wasn't getting everything out. We switched to a ZeroWater filter and OMG we've turned into water snobs! The filter says to change when the tester reads .09 dissolved solids and we can tell a difference when it reaches only .03 dissolved solids! Our filter lasts about 30 days and we use ZeroWater for boiling water(for pasta) and all of our cooking and drinking needs! Even when I see people in a store that have a ZeroWater product in their cart I have to tell them "you're going to LOVE your water".