Water Heater

Permit Process:

Required Inspections:

Water Heater Plumbing Final:

  • Location Access and Working Space: Shall be installed in accordance with Section M1305 and shall be located and connected to provide access for observation, maintenance, servicing and replacement. Working space: 30 inches x 30 inches.
  • 18 inch stand: Required when water heater is installed in a garage. Water heaters listed as flammable vapor resistant and for installation without elevation and electric water heaters are not required to be elevated in the garage.
  • Where a storage tank-type heater or a hot water storage tank is installed in a location where the water leakage from the tank will cause damage, the tank shall be installed in a pan constructed of one of the following: Galvanized steel or aluminum of not less than .0236 inch in thickness, plastic not less than .036 inch in thickness, or other approved materials.
  • Corrosion Resistance: Pan Required for installation above 1st floor. Corrosive resistant ¾ inch drain line required to discharge at a visible location: exterior above grade, floor sink, mop sink. T&P line may NOT drain to Pan.
  • Shutoff Valve: A shutoff valve is required on the cold water supply and is readily accessible. Dielectric unions not required for hot and cold lines.
  • Pipe Insulation: Pipe insulation is required on first 5 feet of hot and cold water pipe and to within 6 inches of draft hood.
  • Temperature & Pressure (T&P) Relief: A temperature and pressure relief valve is required. ¾ inch minimum drain line must run with fall to approved locations: Exterior of building and located between 6 and 24 inches above finished grade, floor sink, or mop sink.
  • Combustion Air (Gas Water Heaters Only): Where located in a confined space (less than 50 cubic feet of area for each 1000 BTU input rating of water heater) a high and low combustion air opening must be provided within 12 inches of the top and bottom of the enclosure.
  • Vent (Gas Water Heaters Only – Ref. footnote for G2428.2.3 of IRC): A double wall (type B) vent must be provided with a min. 1 inch to combustibles. Min. 5 feet vertical required between vent collar and vent cap. Vent may have offsets of up to 45 degrees and one offset of up to 60 degrees. Vent must terminate in a listed vent cap. Vent stack minimum 5 feet.
  • Vent Connector (Gas Water Heaters Only): Single wall vent connector allowed to connect water heater to its vent. Vent connector must be exposed and cannot run into or through concealed construction. Minimum 6 inch clearance to combustibles. Min. pitch ¼ inch per foot.
  • Gas Connector (Gas Water Heaters Only): Accessible and approved valve with maximum 3 feet of flex connector. Connector and valve must not be concealed.
  • Tank-less Water Heaters: Follow manufacturer installation instructions & comply with Int’l Fuel Gas Code for gas line size & vent. A gas load calculation shall be provided on the jobsite when calling the first inspection

What is the Current Code for Water Heater Installation?

CLICK HERE to review Chapter 28 of the 2021 International Residential Building Code regarding Water Heaters

Water Heater Sizing:

Water Heater Sizing is typically sized by a Licensed Plumber or Design Professional  (Licensed by the State of Texas)

For general info on sizing, please see manufactures specs of water heater or visit energy.gov for info regarding water heater sizing.

Click link below to be directed to energy.gov water heater sizing:


Things to consider when sizing:

  • Size of Home
  • Number of Fixture Units
  • Location of Water Heater

Thermal Expansion Tank Info:

What is a Thermal Expansion Tank?

Thermal Expansion Tank:  A means of controlling increased pressure caused by thermal expansion.

When is a Thermal Expansion Tank required?

Any residential water system considered a closed loop system shall have a Thermal Expansion Tank provided.

What is a closed loop system?

Any water system that has a backflow prevention device, check valve, and/or pressure-reducing valve

Other FAQ:

Do I need a Licensed Plumber to install a Water Heater?

Yes, a State of Texas Licensed Plumber must install the water heater.

Can a handy man install a water heater?

No, only a Licensed Plumber can install a water heater or Homeowner.

As the homeowner can I pull my own permit and install a water heater? 

A Homestead Exemption permit may be issued to non-licensed individuals to perform plumbing, electrical and mechanical work within the dwelling premises that they own and occupy. Before beginning any work, the unlicensed person must first sign an affidavit stating that the applicant owns and occupies the structure and is responsible for conducting the work to code specifications, provide proof of ownership from Williamson County Appraisal District and pay all required permit fees. Homeowner exemptions do not apply to rental or commercial properties.

Homeowners Exempt Certificate

How long is a permit good for?

Approved permits are valid for six (6) months from date of issuance. If no inspection activity has taken place within the six (6) months, application and renewal fees for resubmittal is required. In order to close permit, all inspections must be completed. Permits are not required to be posted at project address. Inspector must have access to property at time of requested inspection. If no access, re-inspection fee may apply.

Quick Links:


Adopted Codes


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