All necessary plumbing work to be done in connecting any property with a county sewer shall be done by a plumber licensed to do business in this State in a good and workmanlike manner and with good and proper materials, and shall be subject to the approval of the Department of Public Works.
35 Del. Laws, c. 69, § 4; Code 1935, § 1173; 9 Del. C. 1953, § 2217; 55 Del. Laws, c. 85, § 14; 70 Del. Laws, c. 186, § 1; 75 Del. Laws, c. 404, §§ 1, 3.