Summary: A standard feature of property insurance forms is the exclusion of various categories of loss associated with water. The water exclusion clause in the commercial property program (Insurance Services Office forms CP 10 10 10 00, CP 10 20 10 00, and CP 10 30 10 00, current edition) and in the ISO homeowners (current edition) policy excludes loss caused by flood, surface water, water that backs up from a sewer or drain, and water under the ground surface. Though the exclusionary language is quite broad, disputes continue to arise when the language is applied to particular loss situations. For instance, the meaning of flood, surface water, water below the surface of the ground, and water that backs up through sewers or drains has not gone unchallenged nor has it met with unanimous agreement among insurance people. The controversies created by differing views have led to several court decisions that are discussed below. Although some of the cases cited in this article are old, all have been verified as being valid case law.