News Flash

City of Snohomish - NewsFlash

Posted on: February 6, 2024

Water Main Flushing to Begin this Week

The City of Snohomish Water Department is planning to start flushing the south zone water system (Tenth Street and south)

Main Points

  • The City of Snohomish Water Department is planning to start flushing the south zone water system (all properties Tenth Street and south)
  • Work will begin the week of February 8th
  • This project should be wrapped up by early June.

You may see them in your neighborhood during the day connecting hoses to fire hydrants and discharging water to a sewer manhole or stormwater catch basin. Maintenance and inspection of the fire hydrant is being conducted at the same time. Water Department personnel will be filling the hydrant oil reservoir, checking ports and caps, exercising the isolation valve, weed eating vegetation, pressure washing, and documenting hydrant information, condition, and operating water pressure.

Frequently Asked Questions 

Why does the City of Snohomish flush water mains? 

Flushing helps maintain water quality. The water entering distribution mains is of very high quality; however, water quality can deteriorate in distribution main if the mains are not properly managed. 

Flushing is important. Flushing maintains water quality in several ways:

  • Flushing removes sediment from the mains. These sediments mostly include iron and manganese. Iron sediment results from corrosion of iron pipes and valves used in the distribution system. 
  • Dissolved iron and dissolved manganese occurs naturally in our water and can be changed into sediments under certain low flow conditions. 
  • Flushing helps remove "stale" water. Much of our distribution system is designed with "loops" or interconnected grids, which keep water constantly moving. However, some areas have dead ends where water moves slowly and sits for longer periods of time. 

Although iron and manganese do not pose health concerns, they can be aesthetically unappealing by affection the taste, clarity, and color of the water. In addition, sediments can shield micro-organisms from the disinfecting power of chlorine.  

What will I notice in my neighborhood?

Water Department personnel will set up traffic control signs, and they will operate water valves and hydrants. The water flow will be measured and the chlorine in the water will be neutralized. 

You may notice: 

  •  A slight drop in water pressure.                                                                                                
  • A cloudy appearance to the water (air bubbles).

During flushing try to avoid: 

  • Using cold water to prevent a small amount of sediment in your home or business plumbing.
  • Using hot water to prevent sediment accumulation in the hot water tank.

If this happens, please be patient and allow your cold water to run for a few minutes at full velocity. It is recommended to flush from the bathtub faucet for higher volume and flush the toilets twice to clear any sediment from the tank. If you experience air in the plumbing system, flush from the highest point of the building (upstairs shower head or faucet) to relieve air. 

Sediment and air do not pose a health concern. 

How often should water mains be flushed? 

The City of Snohomish's goal is to systematically flush all distribution mains once every two years. Dead-end mains will be flushed more frequently, depending on several factors, including number of customers served by the water main.

Where does the flushed water go? 

Water Department personnel employ Best Management Practices (BMPs) when conducting water main flushing to ensure that stream and river water quality and habitat are not disturbed. To minimize environmental impact, water is discharged through a diffuser; this dechlorinates, dissipates the energy, and controls the velocity of the discharge.  

Depending on the location, the water may be handled via several different methods:

  • Sanitary sewer where it flows to the wastewater treatment plant.
  • Surface streets with storm drains connected to retention/detention facilities. 
  • Wooded areas or open fields. 
  • Roadside ditches and/or storm drains that discharge to local waterways. 
  • Directly into a water tanker truck if no other suitable option is available. 

Thank you for your patience and understanding as we work to ensure the long term quality of water for our residents and visitors.