Hydrant  Flushing

About Hydrant Flushing

Chances are that at some point, you have noticed fire hydrants being flushed and releasing large amounts of water into the streets. While it may appear that hundreds of gallons are going to waste, there are actually several benefits to this hydrant flushing process. Water main flushing is an important preventative maintenance activity that:

  • verifies proper operation of the hydrant
  • evaluates the available flow to the hydrant 
  • removes mineral and sediment build up from the water mains
  • allows utilities to deliver the highest quality water possible to their customers 

Proper Operation of the Hydrant

The process of water main flushing is one of the most critical practices carried out by public drinking water systems. This practice allows water operators to identify broken or inoperable valves and hydrants to assure that they are working at their maximum potential.

Fire & Emergency Needs

During the flushing of a hydrant, operators can assess the water pressure and available flow rate for firefighting purposes. It’s imperative that each hydrant is operating as firefighters rely on them for fire-ground operations.

Mineral and Sediment Build Up

Throughout the course of several months or a year, loose sediment and mineral deposits may slowly build up inside of the water mains resulting in discolored water and reduced capacity. Flushing the water mains can remove the sediment and mineral build up, and improve the color, odor and taste of the water if it has been problematic.  Unidirectional flushing at the minimum required velocity will improve the carrying capacity of the mains. 

High-Quality Water

Over time, water settles, ages, and is affected by biofilm (a thin layer of microorganisms) that grows on the inside of the distribution piping. Each of these factors affects the quality and taste of the water, so it is important to flush the water out of the mains and hydrants regularly. Flushing can remove water from areas of the distribution system that have low water use, since the older water may no longer have the desired chorine residual.  

Smell something different when turning on tap? That is the “smell of safety”!  

Each spring, Spotsylvania County and the City of Fredericksburg will stop adding ammonia during the water treatment disinfection process for about one month. This annual change is temporary. It is done to ensure a high level of disinfection in water mains and pipes. During this process change, you may notice a change in the taste or odor of your tap water.  View annual public notice HERE.

Hydrant with auto flusher

Auto flusher on hydrant

Closeup of Hydrant with auto flusher

closeup of hydrant with auto flusher

In order to draw this extra purification throughout the entire system, hydrants are then systematically flushed. While water is always under pressure in the pipes, this creates an increased demand and moves water through zones where the pressure may be lower, such as an end of the waterline. It will take roughly 2 months to circulate through the entire water system. You will usually smell the difference as it passes your house, not the entire program period.

 What can I do to prepare for flushing?

If you are sensitive to the taste or odor of chlorine, draw tap water and store it in an open container to allow the chlorine to dissipate. 

When the flushing is taking place, water clarity may temporarily be reduced. Using water for tasks such as dishwashing, laundry, or showering may result in the discoloration/staining of your clothes or household items. Plan ahead and have laundry done before the flushing process begins.

How will flushing affect my water?

During the process, you might experience a difference in the water pressure in your faucets as well as some discoloration in the water.

When will my water be back to normal?

Once the hydrants in your area have completed their flushing, it won’t be long until your water is ready for normal use again. In most cases, water should run clear with just a few minutes of faucet flow. Turn your faucets on cold and let the water run for 5 minutes or so. If you are still seeing discolored water or sediments in the water, continue running cold water on all your faucets until it is clear. Should your water still be discolored after several hours, please contact Public Works.

Is water main/hydrant flushing a waste of water?

Although you will see water flowing for some time, rest assured that most of the water that was flushed will return to a river, stream, or aquifer.  Flushing is a necessary process to help keep our water mains clean and clear of sediment, allowing your public water supplier to provide excellent water quality, and increased pressure and flow.