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Information about the Disinfectant Quarterly Operating Report (DLQOR)

Brief overview of disinfectant-level monitoring and reporting requirements of 30 TAC Section 290.110, which apply to public water systems that use only purchased water or groundwater.

The information summarized in this Web page is available in greater detail in TCEQ publication RG-407, Disinfectant Residual Reporting for Public Water Systems.

Why are public water systems required to track disinfectant levels?

Systems are required to maintain a minimum level of disinfectant to kill microbes that can cause acute diarrhea, nausea, or other life-threatening illnesses.

The maximum level of disinfectant was set by the Environmental Protection Agency (EPA) because of increased risks of cancer to people who drink water with very high levels of free or combined chlorine.

Where are the rules for monitoring and reporting disinfectant levels?

Title 30 Texas Administrative Code (30 TAC), Chapter 290, Subchapter F, 290.110(e) covers the reporting requirements for disinfectant residuals. Monitoring requirements are covered in 30 TAC §290.110(c). Find 30 TAC Section 290.110Exit the TCEQ  online or refer to 30 TAC 290 Subchapter F: Drinking Water Standards Governing Drinking Water Quality and Reporting Requirements for Public Water Systems on the TCEQ rules page.

What types of public water systems must monitor disinfectant levels?

  • Community water systems. A community water system has the potential to serve at least 15 residential service connections on a year round basis or serves at least 25 residents on a year-round basis.
  • Nontransient noncommunity (NTNC) water systems. An NTNC water system serves at least 25 of the same people at least 6 months. For example, prisons, factories, or schools that are outside of city limits or have their own well or water treatment system might be NTNC systems.
  • Transient noncommunity (TNC) water systems. A TNC water system serves at least 25 people at least 60 days. For example, rest stops or convenience stores might be TNC water systems.

Who must submit a Disinfectant Level Quarterly Operating Report (DLQOR)?

All active community and NTNC public water systems that use groundwater or purchased water are required to submit the Disinfectant Level Quarterly Operating Report (DLQOR).

Although TNC systems do not have to submit the DLQOR, they still must monitor residuals, keep disinfectant logs, and keep completed DLQORs on file. These logs and reports must be made available to TCEQ staff during routine inspections and upon request.

How long is a system required to keep records?

Systems are required to keep records of disinfectant levels for at least three years in accordance as required by 30 TAC §290.46(f)(3)(B). These records must also be made available to TCEQ staff during routine inspections and upon request.

What is the acceptable range for chlorine residual? For chloramine residual?

The minimum level of free chlorine required in distribution is 0.2 milligrams per liter (mg/L), if free chlorine is use. The minimum level of total chlorine (chloramines) is 0.5 mg/L if chlorine and ammonia are added to the water to form monochloramine.

The maximum residual disinfectant level is 4.0 mg/L based on a running annual average of all samples in the distribution system.

How often do systems need to submit the DLQOR?

Reports should be submitted quarterly, no later than the tenth calendar day of the following quarter. The quarters are:

  • QUARTER 1 (Q1): January 1–March 31
  • QUARTER 2 (Q2): April 1–June 30
  • QUARTER 3 (Q3): July 1–September 30
  • QUARTER 4 (Q4): October 1–December 31

How many disinfectant residual samples do systems need to take?

The number of samples that your system must take depends on the number of customers it serves. Systems that serve less than 750 people must take a sample at least once per week. Systems that serve more than 750 must take samples daily. Each time that samples are collected, they must be collected at sites representing the entire distribution system. These sites must be represented in the system's monitoring plan. In addition, disinfectant residual must be measured and reported with every coliform sample.

How many disinfectant residual sample sites are needed?

The number of required sites is based on population, from five sites for a system serving less than 4,900 people, to 240 sites for a system serving more than 3,960,000 people. For more information, review Table 4 in TCEQ publication RG-407, Disinfectant Residual Reporting for Public Water Systems. Sample sites must be representative of the entire distribution system.

How is disinfectant residual measured?

Disinfectant residuals within the distribution system must be measured to a minimum accuracy of plus or minus 0.1 mg/L using a colorimeter, spectophotometer, or color comparator test kit. All test kits must confirm to TCEQ and EPA analytical procedures.

Where can systems find a disinfectant residual test kit?

These kits can be purchased for under $500, and may be found in the Yellow Pages under “Water Testing Equipment” or “Water Well Equipment Suppliers.” Some available sources include:

If you have questions regarding test kits from these sources or another source, please contact them directly.

Why can DLQORs no longer be submitted online?

Changes had to be made to the DLQOR automatic data system. Effective as of July 12, 2010, the e-mail submission system was retired because the software process that we use to accept electronic data is no longer functional. Instead, we will be manually entering the data that you send on the signed paper copy that you submit. We are working to replace the software process with a new and improved process. In the meantime, we apologize for any inconvenience.

Why does a system have to send in a hard copy?

Public water systems that must meet the DLQOR requirements must submit a hard copy with an original signature according to EPA's Cross-Media Electronic Reporting Regulation (CROMERR). Under that rule, EPA requires that TCEQ receive an original signature OR have secure electronic signatures. The new software process we are developing will be CROMERR compliant. Eventually we will be able to eliminate the hard copy requirement for any water system that can submit with the new process.

Our system sent in the DLQOR, why are we receiving a notice of violation?

If the TCEQ does not receive your DLQOR on time, you will be sent a notice of violation. The system must send proof that the report was sent on time, such as a signed certified mail receipt, and we will rescind the violation. It will not appear on the system's record and the system will not be required to publish the notice.

What if a public water system did not know they were required to send in the DLQOR?

This requirement went into effect for Texas public water systems in January 2004. The TCEQ has sent three separate letters regarding this issue on August 3, 2003, November 7, 2004, and December 19, 2006. If you do not have record of receiving these documents, please confirm that the mailing and billing information we have for your system is current. You can do so by reviewing your affiliations information in our Water Utilities DatabaseExit the TCEQ. If these letters were being routed incorrectly, you need to contact us at to update the mailing address.

Will the system be subject to enforcement action and associated fines and penalties?

Systems that correct all their violations in a timely fashion will not be referred to Enforcement Division. Systems that have numerous violations may be referred to Enforcement for appropriate action.

How can a system correct their violations?

Systems that have their disinfectant residual logs can still fill out and submit DLQORs for missing quarters. Assessments will be made soon for enforcement referrals.

Do I need to notify the public of these violations?

Yes, any system that receives a notice of violation for disinfectant residual monitoring and reporting must notify the public in accordance with 30 TAC 290.122.

Is there guidance available for monitoring and reporting disinfectant levels?

Basic requirements for disinfectants are covered in TCEQ publication RG-407, Disinfectant Residual Reporting for Public Water Systems. This guidance is intended for public water systems that use only purchased water and/or groundwater. To request one free copy of this publication, contact the TCEQ Publications Section at 512-239-0028 or by e-mail at

Where can I request more information?

Contact the DLQOR Program staff or another member of the Drinking Water Quality Team at 512-239-4691 or e-mail with “DLQOR Information Request” in the subject line of your e-mail.