No person shall permit any water, slops or other liquids to drain into any street or alley, or onto any sidewalk within the city. The natural drainage of rainwater shall not be prohibited by the provisions of this section when the same is from natural elevations, in reasonable quantities, as would naturally occur, and which do not carry filth or other accumulations from off the private property into or onto the streets or alleys. (1993 Code § 22-12)