Dead Leg for Purified Water Storage & Distribution System

Dead Leg for Purified Water Storage & Distribution System

A dead leg within a water distribution system denotes a segment of piping that is no longer actively utilized. It has the potential to foster microbial contamination, thereby posing a risk to the overall quality of the water. Dead legs may arise as a result of alterations in the system’s design, modifications, or the decommissioning of specific outlets. To ensure the purity of the water, it is crucial to carry out routine Dead Leg Verification Procedures.

Dead Leg Verification Procedure:

Identification of Dead Legs:

To begin the process, it is important to thoroughly map out the entire purified water storage and distribution system. By doing so, potential dead legs can be identified based on the system design, any changes that have been made, and decommissioned outlets.


Documentation plays a crucial role in this process. It is essential to maintain accurate and up-to-date drawings of the water distribution system. Any changes, modifications, or decommissioning activities should be recorded to effectively track the creation of dead legs.

Risk Assessment:

A thorough risk assessment should be conducted for each identified dead leg. Factors such as the duration of disuse, proximity to critical points, and the potential for microbial growth should be carefully evaluated to determine the associated risks.

Sampling and Testing:

Sampling and testing are necessary steps in the identification of dead legs. Water samples should be collected from these areas for microbial analysis. Additionally, chemical testing should be performed to assess the quality of water in the dead legs.

Review of System Design:

The review of the system design is crucial to identify any dead legs that may not be immediately apparent. It is important to ensure that the system design minimizes the creation of dead legs.


Once dead legs have been identified, a remediation plan should be developed to eliminate or minimize them. This may involve necessary modifications such as re-routing or removing sections of piping.

Regular Monitoring:

Regular monitoring is essential to effectively manage dead legs. Establishing a routine Dead Leg Verification schedule allows for the regular monitoring and reevaluation of the water distribution system. This helps to promptly identify and address any new dead legs that may arise.

Record Keeping:

Record keeping is of utmost importance throughout this process. Comprehensive records of Dead Leg Verification Procedures should be maintained, including findings, corrective actions, and validation activities. This ensures that a thorough record is kept of all actions taken to address dead legs.

Benefits of Dead Leg Verification:


Guarantees adherence to regulatory obligations, including Good Manufacturing Practice (GMP) and Good Distribution Practice (GDP).

Purity Assurance:

Secures the purity of purified water by reducing the likelihood of microbial contamination.

System Integrity:

Maintains the integrity of the water distribution system, enhancing its durability and dependability.

Risk Mitigation:

Recognizes and addresses potential risks linked to stagnant areas, averting water quality problems.


Question: How to Check that the dead leg in the Sampling lines/ Instrument Connection is not greater than 1.5 times the pipe diameters in the length of the Dead Leg Verification for the Purified Water Storage and Distribution System?


Collect the As-Built Isometric Drawing of the PW Distribution System.

Identify the dead legs in the sampling line and allocate the ID numbering.

Now note the diameter of each dead leg branch pipeline.

Measure the length of the dead leg pipe from the inner surface of the mainline to the end of the branch line.

Now calculate the length of the dead leg by multiplying by 1.5 with the diameter of the branch line.

Repeat the above point for each segment of the pipeline and note the data in the “Test Data Sheet”

 Acceptance Criteria

The length of Dead-Leg shall not be greater than 1.5 times the branch pipe diameter in length.

In conclusion:

A strong Dead Leg Verification Procedure is crucial for industries that depend on purified water for crucial operations. Through a methodical approach of identifying, evaluating, and resolving dead legs, organizations can uphold the utmost standards of water quality, adhere to regulations, and safeguard the integrity of their water storage and distribution systems. Consistent monitoring and proactive actions play a vital role in preserving the purity of water in industries where precision and quality are of utmost importance.

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