common enemy rule
common enemy rule
A rule of water management and rights followed in some states. It holds that excessive rainwater is a common enemy that damages property at random. Uphill property owners can take any steps to protect their land from the water, even if it causes damage to the property of others further down the hill. The downhill property owners are supposed to protect their own land, because water is the common enemy and everyone has to provide their own protection. Today, most states have modified rules that require everyone to act reasonably under the circumstances in order to protect their own property and avoid damaging the property of others.