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 the Philippines and PEM, domestic wastewater discharges, agricultural wastewater, and industrial wastewater are the three main sources of water pollution. These are also known as "point sources" that emanate toxic substances into "non-point sources" or certain bodies of water. Domestic wastewater consists of sewage containing organic waste, solids, and coliforms produced by domestic activities such as laundry, bathing, cooking, and other kitchen activities. Agricultural wastewater, the major source of pollution in rural areas, contain pollutants resulting from agricultural and livestock activities like the maintenance of piggeries which usually do not have proper wastewater treatment facilities. Different industries also contribute largely to the