Coagulation removes dirt and other particles suspended in water. Alum and other chemicals are added to water to form tiny sticky particles which attract the dirt particles. The combined weight of the dirt and the alum become heavy enough to sink to the bottom during sedimentation. It is an important part of homeostasis, the cessation of blood loss from a damaged vessel, wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel. Disorders of coagulation can lead to an increased risk of bleeding or obstructive clotting .