Plumbing and HVAC rules in Delaware
What the state says about plumbing and heating and cooling work, with the page each rule comes from. It's a summary of the published rules, not legal advice, and your city or county can have rules of its own.
Checked September 23, 2026
Plumbing licensing
In Delaware, master plumber licenses are held by individuals and issued by the Board of Plumbing, Heating, Ventilation, Air Conditioning and Refrigeration Examiners.1, 2, 3
Heating and cooling licensing
Plumbing and mechanical codes
Delaware's plumbing code is the 2021 International Plumbing Code with state amendments, in effect since August 11, 2022.5
Permits to replace a water heater, furnace or AC
Delaware's plumbing code requires plumbing permits, but the Division of Public Health requires no permit or fee to replace existing equipment, and it names water heaters. Relocated or new equipment needs a permit, and permits for heating and cooling work are local.5
Backflow testing
If your home has a backflow preventer, your water utility can tell you whether it needs testing and who can test it.
Sources
What plumbing and HVAC work costs in Delaware
Published national ranges for plumbing, water heater, sewer, AC, heat pump and furnace jobs, and a planning estimate for your own job.
Contractors in Delaware
141 plumbers and heating and cooling contractors are listed in Delaware. 38 hold an active USDOT registration. Browse them by county, or ask for quotes and we'll pass your job to contractors near you.
Cite this page
“Plumbing and HVAC rules in Delaware.” PlumbingInformationSite.com, updated September 27, 2026. https://plumbinginformationsite.com/de/rules/