WTF? (When to Flush) Your Drinking Water Pipes for Lead Exposure Reduction?
Flushing guide for water systems to share with customers to reduce lead exposure in their drinking water.
Posted on November 14, 2023
Everyone is familiar with the term “flushing,” but most people associate that word with replacing dirty toilet water with clean water. However, customers can use flushing as a Daily Water Care tool to reduce their lead exposure from drinking water by replacing old water in contact with lead-containing plumbing with fresh water from the main. Customers can also use Intensive Flushing to reduce their lead exposure following a replacement or disturbance1 of their service line by increasing the water flow through their pipes to flush out any remaining lead particles.
Before describing these lead reduction flushing protocols, it is important to note a related topic that sometimes gets confused with customer-initiated lead reduction flushing protocols. The Revised Lead and Copper Rule (LCRR) prohibits pre-stagnation flushing and aerator removal/cleaning before compliance sampling, as these practices can potentially reduce lead levels in a compliance sample. More details can be found in a 2016 EPA memo.
Flushing associated with reducing lead in your customer’s drinking water can be broken into two categories, each with unique processes and objectives.
Daily Water Care: This is not an LCRR requirement but a best practice that can be shared with customers to enable them to protect their families.
When water sits stagnant for an extended time in lead-containing pipes or fittings, lead can be released into the water and potentially be a source of lead exposure at the tap. One method to reduce this exposure is to flush away the stagnant water and replace it with fresh water from the main. This process involves turning on your tap and allowing water to flow to the drain before using the water for consumption. A key question with this process is: How long should I flush?
Each home is unique and contains varying networks of drinking water pipes with different lengths and diameters. The varying network impacts the water volume you are trying to flush out. In addition, each outlet has a different flow rate, which also impacts the time it takes to flush out a certain amount of water.
120Water developed a Daily Water Care Guide that water systems can use to distribute to customers to help reduce lead exposure. This Guide targets homes with a lead service line or leaded plumbing components and can be used as often as needed based on household water use. The 3-5 minute flushing recommendation is a conservative approach to ensure that most homes using that duration would have flushed out stagnant water in contact with household pipes and service lines and be drawing fresh water from the main.
Some industry guidance recommends shorter flushing times (e.g., 30 seconds) for daily water care. Shorter flushing times may be appropriate to displace water in contact with a faucet, but research has shown it can take several minutes of flushing to get to fresh “main water” under typical household plumbing configurations and flow rates. Guidance with shorter flushing could increase lead exposure to customers. Water utilities should ensure that their recommended flushing duration aligns with their flushing objectives and consider typical piping configurations at buildings in their system. Customers are less likely to adhere to longer flushing times, so it is essential to empower them with information so they can make appropriate decisions. It is also important to note that Daily Water Care instructions should be considered outlet-specific, and flushing from one outlet does not necessarily impact other outlets.
Intensive Flushing: Distributing flushing guidance to customers following certain replacement and disturbance activities is an LCRR requirement.
When Lead or Galvanized Requiring Replacement1 service lines are replaced or disturbed2 small pieces of particulate lead can remain in the premise plumbing and service lines following the procedure. Flushing removes these small pieces of lead and reduces lead exposure at the tap. However, this flushing procedure differs from the “Daily Water Care” procedure. This flushing process, defined as “Intensive Flushing,” uses the velocity of water flowing through pipes to push leftover lead particles through the pipes and to the drain before water is consumed. The LCRR requires that water systems provide flushing instructions to customers for replacement and disturbance2 scenarios before the affected service line is returned to service, including the following:
- Partial LSL Replacement,
- Full LSL Replacement
- Shutting off the water or bypassing the service line for LSL, GRR, or Unknowns
120Water developed an Intensive Flushing Guide that water systems can use to distribute to customers to help reduce lead exposure in these scenarios. A key aspect of this guide is the removal of aerators and turning all household outlets on “full blast” for 30 minutes to allow the maximum amount of water to flow through the pipes and flush out any remaining lead particles. The guide recommends performing this flush every few weeks for three months to reduce lead exposure risk following service line replacement or disturbance2. Utilities may receive customer pushback related to the amount of water used during this flush. They should be prepared to offer one-time bill credits or other solutions to customers concerned about the cost of performing flushing.
Aerator Cleaning: This is not an LCRR requirement but a best practice that can be shared with customers to enable them to protect their families.
While not a “flushing” procedure, cleaning faucet aerators can also be part of a comprehensive strategy that customers can use to reduce lead exposure in homes with lead-containing pipes and components. Aerators are standard on many faucets and reduce the water flow. Lead particles can get trapped in aerator screens and be randomly released. Periodic cleaning of these aerators can help to reduce lead exposure.
120Water developed an Aerator Care Guide that can be provided to customers to allow them to perform actions that lower their potential lead exposure. While the LCRR does not require this information to be distributed to customers, it allows the water system to continue building trust with its customers.
Using 120Water to communicate with customers
Water Utilities uses 120Water’s platform to manage all components of water quality programs to send and track communications shared with residents and homeowners. These might include letters, postcards, and texts that are then tracked to the address, ensuring an audit trail of communication. Often, communications need to be triggered in coordination with other programs, such as a pitcher/filter distribution program or a lead service line replacement program. Communication through multiple channels increases program success and completion rates, and studies show that proactive communication builds trust.
In summary, effectively flushing drinking water pipes minimizes lead exposure. Daily Water Care involves regular flushing to replace stagnant water, while Intensive Flushing is crucial after service line activities to remove lingering lead particles. The Aerator Cleaning guide complements these efforts by addressing potential lead buildup in faucet aerators. Following recommended flushing protocols, such as those provided by 120Water, is key to ensuring the success of water quality programs and building trust with customers. Through proactive communication and education, we can collectively work towards a safer and healthier drinking water supply.
1 Galvanized Requiring Replacement is a service line that is or was at any time downstream of a lead service line or is currently downstream of a lead status unknown service line.
2 The LCRR requires additional actions for disturbances to LSL, GRR, and Unknown service lines. Disturbances are defined as:
- Shutting off the water or bypassing the service line. Providing flushing instructions to residents is required before the affected service line is returned to service.
- Replacing the water meter, meter setter, or gooseneck/connector. Provision of flushing instructions is not required, but provision of filters before the affected service line is returned to service is required.