Blood flood is the term used to describe a large amount of blood on a surface. Blood floods are usually a result of sapping, which is harvesting blood from a human. If a sapped human is left unconscious with an open wound after their blood is taken, this may cause a blood flood and ultimately their death. Most Dwellings have a specific type of blood associated with them, and depending on the type, they may destroy materials or living things. Water blood melts or burns things in its path due to its high temperature, so a Water blood flood is potentially dangerous to animals if they come into contact.

Blood flooding is responsible for the destruction of grass at Wild Cemetery.