Call
Info

How To Connect To A Fire Hydrant

In most US areas, individuals who need temporary water may purchase permits to use hydrants. The permit will generally require a hydrant meter, a gate valve and sometimes a back-flow preventer.

Most fire hydrants have two 2.5 inch hose connection outlets with 7.5 threads per inch (TPI) and one 4.5 inch-pumper connection outlet with 4 threads per inch. National Hose (NH) or National Standard Thread (NST) is often referred to as “fire hose thread” as this is by far the most common thread in use today by fire departments.

Two Ways To Determine Hydrant Size

Individual should contact their local fire department, water services or public works to determine the specifications.

You may also count threads per inch (TPI) and/or measure the outside diameter of the male (ODM) outlet to help determine thread type.

Commonly Used U.S. Fire Hose Connection Threads
Male National Standard
Size NH or NST
Inside Diameter Male Outside Diameter of Male Threads Per Inch
1 1/2" 1.990 9
2" 2.515 8
2 1/2" 3.068 7.5
3" 3.623 6
3 1/2" 4.243 6
4" 5.010 4
4 1/2" 5.760 4
5" 6.260 4
6" 7.025 4

How To Connect To A Standard 2 1/2" Hydrant With NH / NST Threads


Products Needed:

  • One fire hydrant wrench
  • One adapter 2 1/2" Female NH / NST to 1" Male NH / NST
  • 1" Single, double or rubber covered hose with NH / NST threads
  • 1" NH / NST nozzle

Products Needed:

  • One fire hydrant wrench
  • One adapter 2 1/2" Female NH / NST to 1 1/2" Male NH / NST
  • 1 1/2" Single, double or rubber covered hose with NH / NST threads
  • 1 1/2" NH / NST nozzle

Products Needed:

  • One fire hydrant wrench
  • 2 1/2" Single, double or rubber covered hose with NH / NST threads
  • 2 1/2" NH / NST nozzle

Products Needed:

  • One fire hydrant wrench
  • Hydrant ball valve with 2 1/2" NH / NST female inlet by 2 1/2" NH / NST male outlet
  • 2 1/2" Single, double or rubber covered hose with NH / NST threads
  • 2 1/2" NH / NST nozzle