Water Quality Recommendations for Homes After a Period of Low or No Use

During periods when a home or part of the home is unoccupied and water is not used for a long time, problems can arise to deteriorate water quality.

Why It Matters

During periods when a home or part of the home is unoccupied and water is not used for a long time, problems can arise to deteriorate water quality, leading to possible issues:

• Can result in increased bacterial growth
• Can result in loss of disinfectant chlorine residuals
• Elevated levels of harmful disinfection byproducts.
• Stagnant water in corroding iron pipes might also develop an undesirable color
• This stagnant water can be unsafe for consumption

To protect the health and safety of occupants, WSSC Water recommends that before using the water for the first time or after long vacancy, homeowners take the steps outlined below to inspect and maintain water quality. For assistance with carrying out these recommendations, consult with a WSSC Water registered licensed plumber to make sure your water is safe.

WSSC Water created these recommendations to help customers restore water quality after periods of low or no use. The intent of these recommendations is to help restore water quality due to possible stagnation and does not address water quality issues that existed prior to stagnation. These recommendations are based on guidelines from the U.S. Environmental Protection Agency, the Centers for Disease Control and Prevention, and the American Water Works Association. Every home is different and may require unique methods to restore water quality.

Before You Flush

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• First, notify everyone in the home not to use or consume water until flushing is complete.
• We recommend that flushing be performed with proper ventilation and wearing masks to avoid potential infection with Legionnaires’ disease. Opportunistic pathogens such as Legionella can grow in the water that is stagnant for a long time and become airborne when you use water.
• Remove and clean all aerators (leave aerators off during flushing); clean all faucets and showerheads; discard any accumulated ice.
• Water treatment systems, such as whole-house water treatment, point-of-use filters, or water softeners, may need additional maintenance. Homeowners must determine if it is feasible to temporarily disconnect or bypass these devices because most of these treatment devices remove chlorine. Flushing is more effective when chlorine is present in the water.
• Take steps to prevent backflow or the siphoning of contaminants into plumbing (e.g., close valves separating irrigation systems from home plumbing, disconnect hoses attached to faucets).
• Take steps to prevent flooding or damage; make sure drains are open and clear.

Flushing Instructions:

Complete a sequential flush with cold water. 

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1. Open faucets one-by-one, starting with the one closest to the point of entry. Start from the lowest level and move up to the highest floor. 
2. Once all faucets are open, let the water run from all faucets for 10 minutes.  
3. Close faucets in the same order, starting with the one closest to the entry point.

Complete a sequential flush with hot water:

1. Open faucets one-by-one, starting with the one closest to the point of entry. 
2. Start from the lowest level and move up to the highest floor. 
3. Once all faucets are open, let the water run from all faucets for 10 minutes.
4. Add additional time for tank water heaters. It can require roughly 45 minutes to fully flush a typical 40-gallon hot water tank. 
5. Close all faucets.

Contact Us

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Additional precautions may be warranted if there are still concerns about water quality. If you experience water quality problems even after flushing, such as discolored water or taste and odor.

• Call 301-206-4002
• Email: waterqualityinquiry@wsscwater.com

Questions still? We have answers...

Flushing FAQs