Properties of water equal to that of the hydrogen ion (), which gives a pH of 7 at 25 °C. Action of water on rock over long periods of time typically leads to weathering and water erosion, physical processes that convert solid rocks and minerals into soil and sediment, but under some conditions chemical reactions with water occur as well, resulting in metasomatism or mineral hydration, a type of chemical alteration of a rock which produces clay minerals. It also occurs when Portland cement hardens. Water ice can form clathrate compounds, known as clathrate hydrates, with a variety of small molecules that can
Water supply and sanitation in Israel of groundwater was first introduced, has shown a constant improvement in the quality of drinking water, with the percentage of violations decreasing from 8.4% in 1989 to 2.1% in 1999. In 2000, the Minister of Health signed an amended version of public health regulations which raise chemical standards for water quality to very stringent standards. Maximum levels for 38 new chemical substances—including pesticides, organic solvents and petroleum products—were set for the first time while existing standards for nitrates, lead, cadmium and zinc were tightened. The salinity of supplied water in Israel varies from very low salinity water (10 mg/l of