In general, the water quality is very good with no residual chlorine smell like in the U.S. but you will want to buy a Brita water filter as the water here is extremely hard. The filters in the U.S. are optimized to remove chlorine. Here, they are optimized to remove minerals; lime (Kalk) is especially prevalent and important to remove. You will want to use filtered water in your iron and when making coffee and tea. Even if your iron or coffee maker has a lime removal system built in, you will obtain better results using the Brita filtered water.
You will need to buy special salt (Geschirrspulersalz) for conditioning the water in your dishwasher. You'll also want to add special Antikalk tablets to your washing machine with every wash to prevent the lime build up on the machine (where it would eventually break the pipes) or your clothing (where it would eventually made the towels grey and less fluffy). If you prevent the lime from building up by consistently using the tablets, there's nothing to worry about.