Hi there! While our pitcher filters work well to reduce chlorine, cadmium, copper, mercury and zinc from municipally treated tap water, hard water can contain different contaminants, such as calcium and magnesium carbonates, that won't be removed. As long as your water is municipally treated, you can still use our Brita filters in order to achieve better-tasting water. We hope this helps! Mel from the Brita team
It removes some contaminants but there are other more hardcore, but also more expensive, filter pitchers on the market. You should shop around if your water is very contaminated. I live in NYC and our water is fairly clean as it comes from a freshwater reservoir upstate. For my use this pitcher is more than adequate and makes the water taste even better but YMMV depending on what your local water supply is like. Except to pay considerably more for one of the more advanced filters.