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Frequently Asked Questions (FAQs) about the Disinfectant Quarterly Operating Level Report (DLQOR)

Brief overview of disinfectant-level monitoring and reporting requirements, 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 Adobe Acrobat PDF Document.

Why are public water systems required to track disinfectant residual 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 total chlorine.

Where are the rules for monitoring and reporting disinfectant levels?

Monitoring requirements for disinfectant residuals are covered in Title 30 Administrative Code (30 TAC), Chapter 290, Subchapter F, 290.110(c). Reporting requirements for disinfectant residuals are covered in 30 TAC §290.110(e).

You can 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 residual 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. A 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 transient noncommunity systems do not have to submit the DLQOR, they still must monitor disinfectant residuals, and keep disinfectant logs and 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 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 free chlorine or chloramine residual?

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

The maximum residual disinfectant level (MRDL) is 4.0 mg/L, which is based on a running annual average of all samples in the distribution system. A single high sample will not necessarily put the system in violation, as long as the monthly average is below 4.0 mg/L.

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
    • DLQOR due April 10
  • QUARTER 2 (Q2): April 1–June 30
    • DLQOR due July 10
  • QUARTER 3 (Q3): July 1–September 30
    • DLQOR due October 10
  • QUARTER 4 (Q4): October 1–December 31
    • DLQOR due January 10

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 and service connections it serves. Systems that serve less than 750 people AND less than 250 connections must take a sample at least once every 7 days. Systems that serve more than 750 people OR more than 250 connections 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 TCEQ publication RG-407, Disinfectant Residual Reporting for Public Water Systems Adobe Acrobat PDF Document. 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, spectrophotometer, or color comparator test kit. All test kits must conform to TCEQ and EPA analytical procedures.

Where can systems find a disinfectant residual test kit?

These kits can be purchased. Some available sources include:

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

Can the DLQOR be submitted online?

Yes, the DLQOR can be submitted using the E2 STEERS website. For more information on submitting using this method, please go to https://www.tceq.texas.gov/drinkingwater/e2-reporting-system.

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

If the TCEQ does not receive your DLQOR on time, the system 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 public 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. It is the responsibility of the PWS owner to ensure its operation complies with applicable rules and regulations, including monitoring and reporting requirements.

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 the Enforcement Division. Systems that have numerous violations may be referred to Enforcement for appropriate action.

How can a system correct their violations?

In order for a system to return to compliance, the next quarter's DLQOR must be submitted on time, filled out completely, and signed by a licensed water operator. Alternately, past DLQOR violations will not be returned to compliance if the system will receive a treatment technique violation or maximum residual disinfectant level (MRDL) violation, based on the data received on the next submitted quarter's DLQOR. 

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 disinfectant residuals are covered in TCEQ publication RG-407, Disinfectant Residual Reporting for Public Water Systems Adobe Acrobat PDF Document. 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 puborder@tceq.texas.gov.

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 PWSCHEM@tceq.texas.gov with “DLQOR Information Request” in the subject line of your e-mail.