Del. Code tit. 16 § 7904
Every political subdivision within the State, including county, city or municipal governments, shall enforce the International Plumbing Code (IPC) as adopted or modified by the Division of Public Health. Every political subdivision retains the right to propose additional or modified plumbing regulations, which must be submitted in writing to the Division of Public Health for review and approval. The Division of Public Health, within 60 days of receiving such proposed changes or additions, shall consult with the State Board of Plumbing, Heating, Air Conditioning, Ventilation and Refrigeration Examiners, and may thereafter adopt, modify or reject the proposed changes or additions. Upon issuance of the statewide plumbing regulations every political subdivision shall have the option of adopting and enforcing said regulations, or adopting and enforcing the minimum standards set forth in the most recently adopted version of the IPC.
16 Del. C. § 7904