An essential part of our system’s maintenance program is to flush hydrants every spring and fall in an effort to clear our water mains of sediment and mineral build up. This practice improves water quality and helps to extend the life of our water mains.

Has concluded. Dead-end water mains North of Hudson Road including Old Sudbury Road have been flushed. Spring 2021 flushing will involve areas South of Hudson Road.

Flushing may impact the water in homes. Before running washing machines during this time residents should ensure their water is not cloudy, which indicates the presence of minerals. Residents should also bypass their filtering systems, including water softeners and refrigerator filters for a day or two following the flushing. If water appears cloudy, residents should run cold water in a bathtub until running clear.

Routine Overnight Flushing is suspended until further notice.


Avoid running your tap water or using a washing machine or dishwasher while flushing is conducted in your area. How do you know if flushing will effect your area? Sign up to receive alerts by text, email or phone. Major route changes will also be posted to this site.

If discolored water occurs due to area flushing, run a cold water faucet (after flushing ours) for a few minutes until the water runs clear or check for discolored water before using a washing machine or dishwasher.

If your white clothes or fabrics become stained due to discolored water, (only when water is running clear from your faucet) re-wash your laundry using detergent together with a Rust and Iron removing agent. Our business office maintains a free supply of Rust and Iron remover, though presently closed to public access, call ahead 978-443-6602 and a member of our staff will leave a few containers outside of our main entrance door.

Slight discoloration may sometimes linger for a few hours, it is not harmful to your health and only temporarily affects the appearance of the water it does not influence water quality.

If water pressure or volume seems low after flushing has been completed, check your faucet screens and home filters for trapped particles.

Flushing water mains may cause iron and manganese sediment to become more visible. Your water may at times appear yellow to dark brown in color (the actual minerals lifting in the water) and may also appear milky at times (air bubbles caused by the opening of the water mains). These non-health threatening minerals are known to cause staining. Be a wary consumer, to minimize the effect of these naturally occurring minerals, avoid using and/or purchasing products that contain chlorine (including automatic dishwashing detergents, laundry detergents, and any other household cleaning agents). Products free of chlorine are now available at most local grocery and department stores. Flushing also has an affect on water pressure. When in the area or your home, you may experience a reduction in the pressure coming into your home. That is because of the high pressure that is being drawn at the hydrants at the times of flushing.

When flushing mains; even if we are not directly ON your street, the connecting streets COULD experience some, all, or none of the same affects as that of the actual street being flushed.

Flushing during periods of restriction 

Water main flushing is necessary to preserve water quality in the distribution system. Our goal is to flush all mains in our system each year. We cannot flush in the winter, because water that is flushed from hydrants could form ice and make driving and walking dangerous. We cannot flush in the midst of high demands periods, because that would be a burden on our system and leave us with no available flow for fire emergencies. That leaves us with a window of time in the spring and the fall, and occasional periods in the summer.

Every water system will gradually accumulate sediments in the water mains, and those sediments lead to reduced quality of water. When there’s a high localized demand and therefore higher than normal flows in the main, sediments are scoured into the flow of the water, creating discoloration. Furthermore, the sediments in the system, even when not stirred up, will react with chlorine, causing a reduction in chlorine at the points farthest from the dosing point. To counter that and provide sufficient disinfectant throughout the system, a higher dose of chlorine would have to be used, which can cause objectionable taste to the water for those who live closest to the dosing point and cause the formation of unwanted disinfection byproducts. Therefore, flushing is needed to protect water aesthetics and public health.

The Sudbury Water District is currently under water-use restrictions required by the Massachusetts Department of Environmental Protection (DEP) based on reduced water levels in the Concord River. DEP places those restrictions on usage as a measure to prevent further reduction in flow in the Concord River and other rivers and streams nearby, thereby protecting the environments of those water bodies. However, DEP allows us to flush our mains during this restriction period in recognition of the value that flushing provides.

When restrictions are in place, we still plan on flushing our water mains as much as possible. If we start to face high demand periods and our system’s pumps and piping cannot tolerate the additional demand from flushing, we will have no choice but to stop flushing altogether. Provided that is not the case, then we plan to continue to flush until the entire system has been addressed for the year. Our goal is to produce the highest quality water at the tap, and flushing is needed for us to meet that goal.