No. Even with the sediment filter in a reverse osmosis system, reverse osmosis is not able to remove or reduce magnesium and calcium as effectively as a water softener. In fact, hard water that passes through a reverse osmosis system can cause mineral build-up and decrease the effectiveness of the reverse osmosis system's membrane, which can decrease the quality of the water it produces. This is why it's recommended to have both a water softener and a reverse osmosis system.Some systems both filter and soften water. Using a water softener with whole-house filtration produces the cleanest, purest water. Check out the Evolv Whole-House Water Filtration and Softener System to learn more.