Hydrant Flushing Facts and FAQs

Conventional Water Main Flush

Conventional water main flushing is a method of opening each hydrant on a section of water main without closing any water main valves. This method can be completed more quickly than unidirectional flushing, however this method uses more water than unidirectional flushing.

How often is hydrant flushing done?

Hydrant flushing is performed two times per year, once in the spring and once in the fall.

What are the effects of conventional water main flushing?

Flushing ensures water quality and helps avoid random occurrences of rusty water when there is a high demand for water.

Sometimes hydrant flushing can make the water temporarily appear rusty/brown in color because the iron and mineral deposits get stirred up when the water is tuberculated.

Why is my water rusty/brown in color from hydrant flushing? Is the water safe?

Hydrant flushing can make the water appear temporarily rusty/brown because the iron and mineral deposits in the water get stirred up. The water is safe to use and consume during hydrant flushing, however it may stain laundry.

The main component of the discoloration of the water during flushing is caused by iron deposits inside the water main piping. The source of the iron is naturally occurring from ground water wells and deposits in the ductile iron piping that make up the distribution system.

The Illinois Environmental Protection Agency dictates a current maximum level of 1.0 parts per million. The City of Yorkville iron level is historically between 0.0 - 0.117 parts per million. One part per million, or one milligram per liter (mg/l), would be equal to putting one (1) drop of water from an eyedropper into ten (10) gallons of water.

What should I do if my water is discolored?

Run the cold water tap until the water runs clear. If you have a water softener and are experiencing discolored water, place the unit into regeneration or cleaning mode after flushing is completed in your area. Rust colored water is safe, but could still stain laundry. If this happens, keep clothes wet and treat them with a stain remover. The City of Yorkville offers a free "Iron Out" detergent powder if needed that can be dropped off at your residence.