• Refine Search

  • All Results

All about Hydrants

The Milwaukee Water Works owns and maintains 20,000 hydrants in Milwaukee, Greenfield, St. Francis, and Hales Corners. The hydrants are part of the utility’s water distribution system of 2,000 miles of underground water mains, all connected to the water treatment plants. There are 13 styles of hydrants.


Inspection and flushing

Distribution staff inspect 10,000 hydrants every year during warm weather months. Some are flushed annually or even nightly to ensure they are operable for the fire department and that water in the distribution system is clean and safe.


Each hydrant is labeled with a bar code to identify it and electronically store information about the hydrant in a database. Field staff enters data into a tablet which is automatically downloaded into the data base. During inspection and flushing, each hydrant is:

  • Operated fully
  • Flushed thoroughly to remove any stagnant water
  • Put under higher water pressure to test for leaks
  • Shut off to ensure it drains properly
  • Inspected for any wear on moving parts

Any hydrant defects noted from the inspection are reported for repairs. If there were any problem with a hydrant it would be recorded in the data base and the information is easily accessible to the Distribution section.A plastic ring color system provides further identification of hydrants.A plastic ring color system provides further identification of hydrants.


When a hydrant is found to be inoperable, the Milwaukee Water Works promptly notifies the Fire Department of the out-of-service status and again when the hydrant repair is complete.


While flushing each hydrant during inspection, the water is sampled to ensure our water quality standards are met or exceeded throughout the distribution system. The stored hydrant data includes:

  • Flow rate in gallons per minute
  • Turbidity, or clarity of the water; flushed to 5 NTUs or less
  • Chlorine residual. Each hydrant is tested for chlorine residual levels of 1.4 to 1.5 ppm. Chlorine residual protects against bacterial contamination. The Wisconsin Department of Natural Resources (DNR) requires water utilities to maintain a detectable level of disinfectant throughout the distribution system to maintain bacteriological protection.

We also flush about 1,000 hydrants that are located at the end of a dead-end water main. This flushing helps ensure that fresh water is moved through the main.


How we identify hydrants 

A plastic ring color system provides at-a-glance information.

  • Yellow -- The hydrant was taken out of service due to a problem. The appropriate fire department is notified. Water Distribution repair crews are promptly assigned to conduct necessary repairs.
  • White -- For fire department use only. These hydrants may hold water in the standpipe after operation. The Milwaukee Water Works checks these hydrants each fall to ensure they are dry before freezing weather. With water in the standpipe the hydrant would freeze and be inoperable during cold weather months. If the fire department uses one of these hydrants it notifies the Milwaukee Water Works to check it and clear it of any standing water.
  • Lime Green -- The hydrant is in use by someone with a permit using a backflow prevention device.
  • Green -- Private hydrant. The hydrant is not owned nor maintained by the Milwaukee Water Works.
  • Blue -- The hydrant is located at the end of a dead-end water main. These hydrants are flushed annually in addition to the inspection flushing.

Hydrant painting

The Milwaukee Water Works regularly paints the hydrants every 8-10 years to maintain the finish and prevent corrosion.

  • Most of the hydrants are painted the traditional red color.
  • Yellow paint indicates a hydrant's water supply is from a water main different from the average installation. Most hydrants face the street and the water main to which they are connected. A yellow hydrant may face a street but may be connected to the water main on the side street or in the pedestrian way.
  • Hydrants with green tops, or bonnets, are attached to water mains that are 12" in diameter or larger. When a fire department responds to an emergency, personnel can easily find a hydrant with the capability to support and maintain additional hookups to meet fire suppression needs. Thanks to OnMilwaukee.com for asking, "Why the green paint on Milwaukee's red fire hydrants?

It is illegal to open a hydrant without permission

It is dangerous and against the law to open fire hydrants without permission. The penalty for tampering with a hydrant is a $1,000 fine or 30 days in jail. Only the fire department, the Milwaukee Water Works, and specially permitted projects are allowed to open hydrants.

Please report tampering and open hydrants 24 hours a day by calling the Milwaukee Water Works Control Center at (414) 286-3710.


  • Illegally opened hydrants cause water pressure to drop, making it difficult to put out a fire.
  • Breaking open a hydrant makes it unusable to put out a fire.
  • The strong water spray is hazardous and motorists may not see pedestrians in the spray.
  • The spray obstructs the view of motorists and can cause accidents.
  • Illegally opened hydrants waste millions of gallons of treated water as it drains into sewers.
  • Wasting the water is expensive to everyone and a waste of a precious resource.


What do you do with old hydrants? Can I buy one?

We recycle the hydrants but Public Service Commission of Wisconsin regulations prohibit a utilty from selling hydrants. On occasion, we have provided an old, non-renewable hydrant to the Milwaukee Fire Department for use in a charitable fundraising event. You may see a hydrant here or there in someone’s yard but we did not sell it to them. Policies about hydrants vary among water utilities in the United States. For that reason, you might be able to purchase a new or used hydrant on the Internet.

This site is powered by the Northwoods Titan Content Management System