Young people in the neighborhood can help. Do the same for broken street lights, graffiti, cracked pavements, and trash removal. Property owners can give police permission to enter private property, such as parking lots or outside stairs, to investigate and possibly arrest loiterers. Telephone companies can fix pay phones so they can be used only for calls out - then, drug dealers can't use them to conduct business. Utility companies can investigate gas and electric connections that drug houses may be using illegally.
Property owners can rewrite their leases to include specific bans on illegal drug activity.