Water Main (Hydrant) Flushing

Hydrant Flushing - What You Should Know

At different points during the year, you will hear from the City about hydrant flushing and how it will affect you and the water at your home. There are two main types of hydrant flushing: hydrant inspection testing, which is conducted by the Somerville Fire Department, and annual water main flushing, conducted by the Water and Sewer Department. 

What to Expect

In both cases, you may encounter discolored water. It’s important to note:  

• You may notice a temporary, slight drop in water pressure during flushing/testing.  
• While the water may appear discolored, it will not cause health problems and is safe to drink.  
• Though safe to drink, the discolored water can stain clothing and fabric, so avoid laundry until the water runs clear.  
• The discoloration is caused by iron (red color) or manganese (black color) particles being dislodged from the water main which can stain.
• If discoloration occurs, open the cold tap nearest the water meter—usually a basement sink—to full flow until the water runs clear. In some situations, this may take 5 to 10 minutes. 
• If you happen to do laundry while the water is discolored, don’t dry those items!  
• If your laundry is affected by the discolored water, contact 311 (or 617-666-3311 from outside the City or by cell phone) for a free bottle of rust remover. 

Hydrant Testing

The Somerville Fire Department annually conducts inspections of all fire hydrants. As part of the process, firefighters look for any physical damage to each hydrant, remove the caps from each outlet and lubricate the threading, and open and briefly flow the hydrant. These steps allow us to check the mechanical operation of each hydrant, as well as evaluate the water flow and pressure to make sure it will be adequate when needed in the event of a fire.   

Testing usually takes place between 9 a.m. and 4 p.m., but, if necessary, will occur between 6:15-8:15 p.m. Please contact the Somerville Fire Department at 617-623-1700 if you have any questions.  

Water Main Flushing

This Water Department’s annual program flushes pips at high velocities to clean water mains and maintain the highest possible water quality. This is done using hydrants in different specified areas of the City. This process is most often done on Mondays and Thursdays between 6 p.m. and midnight to minimize disruptions to water service.  

Signage will alert residents when their neighborhood might be affected by the flushing program. For more information, contact the Water Department at water@somervillma.gov or by calling 617-625-6600 ext. 5850.