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Temporary Free-Chlorine Conversion

Why public water systems may make a temporary switch from chloramine to free chlorine to disinfect drinking water. How to notify customers and the TCEQ.

How Public Water Systems Disinfect Drinking Water

To protect public health all public water systems (PWS) in the State of Texas are required to disinfect drinking water before providing it to customers. Many PWSs use chloramine (free chlorine and ammonia), an effective disinfectant that persists over a long period of time, making it particularly valuable in areas with high temperatures. 

A water system that uses chloramine may sometimes employ a free-chlorine conversion, removing ammonia from the treatment process, disinfecting the water only with free chlorine. This common practice is used as preventive maintenance to kill bacteria that, though harmless when consumed by humans, can introduce unwanted taste and odor, and create issues with maintaining a disinfectant residual. TCEQ'S regulatory guidance document, Public Water Systems: Temporary Conversions to Free Chlorine (RG-631), discusses how to perform a successful free chlorine conversion.

Notify Customers

Prior to starting the temporary treatment change, the TCEQ recommends that your PWS notify customers, including wholesale customers and their downstream customers. Provide information about the change, possible effects, and expected outcomes.
Send them the following:

Notify the TCEQ

Notify Public Drinking Water staff 30 days before you initiate a free-chlorine conversion. Include this information in your notice to us:

  • PWS ID and name
  • PWS contact name, title, and phone
  • Estimated start and end date
  • PWS ID and names of customer systems
  • Reason for change in treatment

Send by e-mail to

Or by letter to:
Water Supply Division
PO Box 13087 MC-155
Austin TX 78711-3087

Assistance and Helpful Links

TCEQ's Drinking Water Watch holds the information we have for your public water system and is open to the public. This has contact information, sample sites, sample results, violations, and public notice due dates.

Our Financial, Managerial, and Technical (FMT) Assistance program helps public water systems deal with today’s problems. Your water system may get free training, although each system is responsible for having the appropriate materials and equipment on hand. Find more information at Assistance for Public Drinking Water and Wastewater Systems

To participate, contact the Water Supply Division by telephone at (512) 239-4691 or by email at

For advice about process management, changing disinfectants, and other operational matters, contact our Public Drinking Water staff.

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