Homeowner's guide to surface water law
What if you are suffering flooding and damage to your property from water running off from your neighbor’s property? Is your neighbor liable? Must your neighbor take action to avert the water runoff?
In the District of Columbia, the neighbor is most likely not liable. This is because the District of Columbia follows a modified version of the "Common Enemy" rule.
The Common Enemy rule holds that excessive rainwater is a "common enemy" impacting property at random and you are expected to take measures to protect your own property from coursing water; even if the higher ground neighbor diverted water to prevent flooding and deposited the water onto your land.
The modified version of this rule recognized in the District of Columbia provides an exception such that your neighbor may repel or deflect water to prevent flooding on his own property only to the extent that the deflection is of ordinary use. That is, your neighbor may not deflect or divert the water with the use of drainage piping, ditches, man-made channels, or extraordinary construction.
However, in the case of "extraordinary construction," a DC appellate court (see Ballard v. Ace Wrecking Company, 289 A.2d 888 (D.C. Ct. App. 1972)) ruled against the flood-damaged neighbor after the neighboring property improvements had been demolished and graded. The court stated that because the work was not unusual or extraordinary, the neighbor could not be held liable.