It shall be unlawful for any person to wilfully place, introduce or cause to flow or enter into any spring, brook or body of water, which is used in the manufacture of salt, or into any salt well, or salt mine, or into any cavity or reservoir beneath the surface of the earth from which salt or brine is taken or used in the manufacture of salt, any impure or deleterious substance or thing whatsoever, which is liable to pollute the waters thereof, or the brine or salt taken or manufactured therefrom, provided that this act shall not interfere with any existing system of drainage or sewerage.