VITAL FOR MAINTAINING WATER QUALITY AND FLOW
The Hooksett Village Water Precinct flushes fire hydrants throughout the Village area every spring and fall. The hydrant flushing program is very important for the maintenance of the water distribution system, including the water mains, hydrants and associated valves and fittings. During this process, it is not uncommon for a rusty, orange, red, brown or black tint to appear in the water. Flushing the system causes this discoloration by stirring up mineral deposits that normally settle in the water mains. Flushing removes these sediments from the mains and also serves the following purposes:
- Improves water quality in the distribution system
- Verifies the proper operation of fire hydrants and valves
- Helps find weaknesses in the water system
- Checks for closed valves and weak flows in the water mains
- Verifies adequate fire flows for firefighting
FREQUENTLY ASKED QUESTIONS
What should I do when the Precinct is flushing in my neighborhood?
What could my water look like during flushing?
How should I manage laundry during flushing?
What if I notice a change in water pressure during flushing?
Why am I noticing a chlorine taste/odor during flushing?
Is the water safe during flushing?
Does the Precinct flush at other times?
Why doesn’t the Precinct flush the water mains at night?
Is flushing a waste of water?
What if I have questions about the Flushing Program?
If you see the Precinct crew flushing a hydrant on your street, avoid running tap water and using the washing machine or the dishwasher until the flushing is completed. Please drive carefully if you see the flushing crew working in the area.
If tap water is used during flushing, it could come out discolored (commonly a rusty, orange, red, brown or black tint) and contain sediment. If you encounter discolored water, shut the water off and wait several minutes. After waiting, check the clarity by running cold water for a few minutes allowing new water to work its way into your building’s pipes. Do not choose a tap that has a water filter connected to it, or the sediment may clog your filter. Do not use a hot water tap because it could draw sediment into your hot water tank. If the water is clear it is OK to use. If not, wait 15-30 minutes and check again. In some cases, there may be slight discoloration for several hours.
The water may also have a milky appearance. This is almost always due to tiny air bubbles stirred up by the flushing and will eventually dissipate out and is not harmful.
Avoid washing laundry during scheduled flushing days. Sediment that remains after flushing often settles back out in a short time, so waiting to launder until the evening can be helpful to reduce potential staining issues. Wait until the water runs clear at the tap, then wash a load of dark clothes first. Hot water tanks can hold discolored water for some time after the cold water runs clear. If despite your best efforts your laundry is stained because of rusty water from our flushing, you can usually take the stains out by running the washing machine again with an inexpensive heavy-duty rust remover designed specifically for that situation. One that is inexpensive and works quite well is available at http://red-b-gone.com. You may also call our office to see if we have any remover in-stock for immediate use, at no charge.
There may be a temporary drop in water pressure during flushing. If pressure or volume remain low after flushing, check your faucet screens for trapped particles. Flush your hot water tanks, by running the hot water tap for a few minutes after the cold water clears. For persistent pressure or volume problems, please contact your plumber. Sometimes a pressure reducing valve in your plumbing is clogged or has failed, causing pressure loss. Your plumber can advise you on the best course of action.
You may notice a more pronounced chlorine taste or odor in the water during flushing. This is because free chlorine has a more noticeable chlorine taste and odor. This will dissipate when water is left in an open container in the refrigerator. Letting water in a glass sit for a moment will also take care of air bubbles that are stirred up during flushing and cause a milky appearance.
Water is generally safe to use during hydrant flushing, however it may look unpleasing, may taste metallic and/or may stain laundry. The main causes of the discoloration of the water during hydrant flushing are iron (Fe) and manganese (Mn) deposits from inside the water mains. The minerals occur naturally in ground water from our wells, and also originate from corrosion of the iron pipes that were used to build a portion of the water system. Fe and Mn are essential nutrients for life.
Maximum Fe and Mn levels observed at our distribution system sampling stations are typically around 0.2 and 0.05 ppm, respectively. The State of NH has recently adopted an interim health-based Mn standard of 0.84 ppm. The U.S. EPA and NH DES have established secondary limits in drinking water for Fe and Mn of 0.3 and 0.05 parts per million (ppm), respectively. For reference one ppm is equivalent to looking at 1 inch in 16 miles or 1 minute in 2 years. The secondary limits are based on the potential for aesthetic (taste/odor/stain) issues. According to the treatment experts, in most NH cases staining problems do not become objectionable until the actual concentrations of Fe/Mn are at least double the secondary standards.
To minimize the potential for laundry staining, the Precinct adds a food grade polyphosphate to the water to prevent the formation of the rusty forms of Fe/Mn. The polyphosphate "coats" and "ties up" (or “sequesters”) the dissolved Fe/Mn preventing a reaction with oxygen and subsequent precipitation.
Yes, the Precinct will occasionally flush hydrants throughout the year. Usually this is associated with the installation or repair of water mains, but may also be associated with other activities such as troubleshooting various distribution system issues; addressing water quality complaints; maintaining or testing our wells and source meters; hydrant flow testing; and periodic training events. These types of activities are very localized to specific hydrants and typically you won’t even notice it occurring.
It’s safer for staff to work on the streets in daylight. Also, daylight provides better visibility to see when all the sediment has been flushed out and the water is running clear.
No, this is a normal and necessary part of maintaining a safe and reliable drinking water supply. Water that is discharged into the environment will replenish groundwater systems and streams.
If you have questions or concerns regarding flushing, please call or email us.
Credits: Portions of the above information were adapted from the web pages of EAI Analytical Labs, the Town of Lincoln NH DPW and the Western Municipal Water District.
Why Flushing Hydrants and 'Wasting' Water Keeps You Safe
Fire Hydrant Flushing Video
Heavy-duty Rust Remover for Laundry
HVWP Hydrant Flushing Demo
HVWP Hydrant Flushing Demo (Hitch-Mounted Diffuser)