When seeking an answer to the question “What does tap water contain?” one benefits from a broad knowledge of geography and geology. That fact should not surprise those who are familiar with the water cycle, and with the path that water takes to the sea. After a rainstorm, water rushes down from the land into creeks and streams. At the same time, the land absorbs the water, allowing it to travel down to the level of the groundwater. Eventually, the water in the creeks and streams makes its way to a larger body of water. All sources of fresh water can become a potential source of tap water. The chemicals in any one water source ultimately determine the ingredients in tap water, at least in the tap water going to local homes and businesses. That fact sheds some light on the question raised in the first paragraph: “What does tap water contain?” As wate Wusthof Knife Sharpener r washes over soil and rocks, it picks-up minerals. Thus the content of tap water reflects the mineral composition of the surrounding rocks and soil. As water passes over rocks and soil it typically dissolves certain salts in those rocks and in that soil. For that reason, calcium salts, magnesium salts, strontium salts and manganese salts belong on the list of ingredients in tap water. Much tap water also contains a measurable amount of ferrous iron. The presence in tap water of those salts can cause that tap water to show an appreciable level of “hardness.” Most homeowners do not want to have hard water in their tap water. Hard water can cause the formation of a build-up on the inner lining of pipes. In addition, hard water forms a precipitate when combined with soap. Hard water reduces the amount of suds created by soap, when it mixes with water.