DC Water and Sewer Authority

The DC Water and Sewer Authority (DC WASA) delivers drinking water to District of Columbia residences and businesses through an underground pipe distribution system. DC WASA purchases this drinking water from the U.S. Army Corps of Engineers, Washington Aqueduct, a federally owned agency responsible for drinking water treatment. DC WASA conducts water quality monitoring throughout the distribution system to ensure water quality meets the U.S. Environmental Protection Agency�s federal regulatory standards and DC WASA�s more stringent target levels. However, once water leaves the distribution system and enters building pipes, water quality can change. This is dependent on factors such as the amount of water usage and the building pipe construction. In an effort to maintain high water quality in building pipe systems, DC WASA recommends a few tips for commercial buildings.

What is the difference between the distribution system and a building pipe system?

The distribution system begins at the water treatment plant and ends at the building's water service connection, whereas the building pipe system begins at the service connection and ends at the various water outlets in the building. A major difference between these systems is the flow of water moving inside the pipes. Within the distribution system, the water moves at a high rate because water service is in continuous demand from multiple buildings. However, once the water leaves the main in the street and enters the building system, the flow of water slows and is dependent on individual building water usage. Generally, as water usage decreases, the quality of water also decreases.

A few tips to minimize changes in water quality and prevent contamination:

• Flush building system lines after periods of limited or no water usage—Commercial buildings are often vacant during weekends and holidays and experience periods of water stagnation, with limited or no water usage. Periods of water stagnation may cause a reduction in disinfection protection and can lead to increased bacterial growth. Following extended periods of limited or no water usage, locate the tap on each floor that is furthest from the floor's water service riser and flush the tap for 10 minutes. In addition, flush each fountain/tap for one minute or install fountains with automatic flushing devices.
• Change water fountain filters regularly—Most water fountains have filters to remove impurities from the building water system. Filters that are not changed can accumulate these impurities and promote bacterial growth. Change water fountain filters regularly as specified by the manufacturer.
• Clean and replace faucet aerators often—Aerators are strainers that attach to your faucets. Routinely remove faucet aerators and clean screens of debris. In addition, install low-flow aerators to conserve water.
• Inspect and test backflow prevention assemblies annually"Many commercial buildings use water treatment chemicals to protect sensitive building piping and heating/cooling equipment. These chemicals minimize and prevent corrosion and scaling within these systems, but are pollutants or contaminants if introduced to the building's drinking water system. To prevent the reverse flow of these chemicals and protect the drinking water system from contamination, property owners are required to install mechanical devices called backflow prevention assemblies. To ensure these devices are operating correctly, certified testers are required to inspect and test backflow prevention assemblies and submit reports to the DC WASA Cross-Connection Program. More information can be requested by contacting the DC WASA Water Quality Division via email at crossconnection@dcwasa.com.
• Install lead-free and water-efficient plumbing fixtures—Installing lead-free fixtures will prevent lead from entering the building's drinking water system. Water-efficient fixtures, labeled as "WaterSense," conserve water and reduce water bills. Look for "lead-free" and "WaterSense" labels when purchasing new plumbing fixtures.

• Monitor water use"Monitoring water usage is important for building owners. Leaks in toilets, fixtures and pipes increase water usage and can increase customer bills.

  DC WASA operates the High Usage Notification Alert (HUNA) program, an automated meter reading system that detects and alerts customers of high water usage. These alerts may detect a major plumbing problem or leak in the building. Customers can receive alerts through telephone or email. For more information about HUNA and to sign up for alerts, see Sign Up for Alerts in our "Customer Care section" or call 202-354-3600.

• Clean bottled water coolers—Although not part of building plumbing, many buildings purchase bottled water coolers for drinking water. Unlike the water from the distribution system, the water provided in these coolers is not treated to prevent bacterial activity. Cleaning the bottle inlets of water coolers as recommended by the manufacturer helps to prevent the growth of bacteria.

Where can I find more information?

To obtain information regarding backflow prevention, see Cross-Connections or contact the DC WASA Water Quality Division at 202-612-3440, from 8 a.m. to 4:30 p.m., Monday through Friday.