Flushing Water Mains

As part of the maintenance process, City crews flush the water mains. Occasionally this causes a slight and temporary discoloration in the water. The water is completely safe, and we advise that you simply open your COLD water faucet and allow the water to run for several minutes to clear it out. 

If water discoloration persists for an extended period of time, call Water Quality at 720-898-7802 or Water Treatment at 720-898-7820. 

Flushing Process

This year (2023) our directional flushing begins on March 1st and is scheduled to last approximately 4 months. Flushing operations will take place Monday through Friday and will be weather dependent.

Map of Areas Being Flushed in north and west portions of Arvada

Red highlighted areas are where water main flushing will take place in 2023. Click on the map for an interactive address search. 

When is flushing done?

Flushing is usually done when temperatures are above freezing and during business hours. There are sites that need to be flushed after hours because of possible impact on traffic or safety concerns for the flushing crews. 

Where is flushing done?

The City is divided into three somewhat equal parts with one-third being done each year. It takes three years to completely flush the entire water system.

Purpose of Flushing

Flushing helps maintain water quality in water mains.

During the winter months when use is at its lowest, low-flow water areas invite two potential problems. 

  1. Water can begin to go "stale," meaning that the unused water slowly begins to lose its chlorine residual. Chlorine prevents bacteria growth in the system. It's important to flush out those areas before the chlorine levels drop below minimum standards.
  2. Minerals like iron and manganese (essentially rust) can build up when there is less water use. At low levels the minerals provide no health risk. However, when the settled sediment is stirred up again these minerals pass into customers' service lines, water heaters and faucets. If left untended, the minerals will continue to build up in the water main and eventually impede water flow.

Flushing and Water Conservation

This water release may seem like a waste, especially during dry years. In reality Arvada only flushes about 0.1% of its total annual consumption. To conserve water, the City performs unidirectional flushing which uses significantly less water than conventional flushing. Additionally, it is important to note that during flushing, released water goes back into the stormwater system.