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Hydrant Flushing Facts & Frequently Asked Questions

Why does the City perform hydrant flushing?

Hydrant flushing is the quick release of water from fire hydrants.  It’s a controlled procedure that is vital to the general maintenance of the City’s water distribution system.  It ensures adequate water flow is available to fire fighters, residents and businesses.  It also improves water quality by clearing iron and other mineral deposits from the water mains.

What are the effects of hydrant flushing?

Hydrant flushing helps ensure water quality and helps avoid random bouts of rusty water if there is a high demand for water, caused by a major firefighting effort or water main break.

During the flushing of a hydrant, some customers may notice reduced water pressure and flow.

Why is my water rust/tea-colored from the hydrant flushing?  Is the water safe?

Sometimes hydrant flushing can make the water temporarily appear rust-colored because the iron and other mineral deposits in the water mains get stirred up.  There is no health hazard associated with discolored water.  Water is safe to use and consume during hydrant flushing, however it may stain laundry.

Does the City test the water regularly?  Is the testing done at various sites?

The City of St. Charles tests the water both leaving the water plant and throughout the water system regularly, following U.S. and IL Environmental Protection Agency protocols.  Many tests are also completed around the clock during the water treatment process. 

I live on the west side and the City is flushing hydrants on the east side.  How come my water is discolored?

Sometimes residents who live beyond the limits of the area where hydrant flushing is currently being performed, may notice rust-colored water.  This can occur because the opening of a hydrant can cause water run in the opposite direction than normal  Water Department personnel use techniques intended to minimize these impacts. 

How come my water is discolored, buy my neighbor didn’t notice my discoloration? 

If the water inside a home or business is turned on while hydrant flushing is going on, discolored water may enter your plumbing.  If a neighbor did not use water during the day, they most likely will not notice any discoloration. 

My water is discolored.  What should I do?

Wait until flushing has subsided in your area then run a cold water tap until the water runs clear. 

Remember rust colored water is safe, but it may stain laundry.  If this happens, keep clothes wet and treat them with stain remover.

The City offers a stain removal product at no cost to residents at the following facilities: 

  • Public Works located at 1405 S. 7th Avenue
  • City Hall Front Reception Desk located at 2 E. Main Street

If you notice the water flushing crew is near your property, refrain from using water, and delay washing clothes as much as possible.
How often is hydrant flushing done?

Hydrant flushing is performed two times a year – once in the spring and once in the fall.  The work is generally done between 5:00 a.m. and 4:00 p.m. 

Further questions can be answered by calling Public Works at 630-377-4405 or emailing


updated Sep 16, 2020