Water systems using chloramine must report total chlorine residuals and maintain a minimum residual level of 0.5 mg/L throughout the distribution system (401 KAR 8:150). 

Reporting daily includes reporting weekends on the MOR.

The regulation requires collection of residuals at the plant tap and representative points in the distribution system. The minimum free chlorine residual level of 0.2 mg/L must be maintained and the residual level entering the distribution system cannot be less than 0.2 mg/L for more than four hours. Water systems using chloramine must report total chlorine residuals and maintain a minimum residual level of 0.5 mg/L throughout the distribution system.

If a water system fails to report daily free or total chlorine residuals, a violation of "failure to report" will result. Be sure to report on the MOR the daily free chlorine residuals from the distribution system, including weekends, to avoid a violation. The representative points in the distribution system need to be reported on the distribution page. The plant tap residual information needs to be recorded daily on the water quality page of the MOR and is to be the lowest chlorine (or chloramine) residual of the day.   

If the minimum free chlorine residual entering the distribution system is not restored to at least 0.2 mg/L within four hours after a value of less than 0.2 mg/L is observed, the water system is in violation of a treatment technique requirement. The system must restore the minimum concentration to return to compliance.

The monitoring requirements state that the residual disinfectant concentration of the water entering the distribution system must be monitored by public water systems continuously. The lowest value must be recorded each day, including weekends. In order to find the lowest chlorine value of the day, the continuous analyzer must have a continuous recording device.

If there is a failure in the continuous monitoring equipment, grab sampling every four hours may be conducted but for no more than five working days following the failure of the equipment. Systems serving 3,300 or fewer persons may take grab samples in lieu of continuous monitoring on an ongoing basis at the frequencies each day prescribed in 401 KAR 8:150 (number of samples per day based on population size).

The system shall take a grab sample every four hours until the residual disinfectant concentration meets the requirements of Section 1(1) of the administrative regulation. The grab samples must not be taken the same time each day but can be taken at the same points in the distribution system. The residual disinfectant concentration shall be measured at least at the same points in the distribution system and at the same time as total coliforms are sampled (see 401 KAR 8:200 regarding microbiological monitoring).  The sampling interval shall be subject to cabinet review and approval.

If distribution residual disinfectant levels are below the minimum, then heterotrophic plate counts (HPC) should be run to show there is adequate residual in the system to prohibit microbial growth.  Water in the distribution system with a heterotrophic bacteria concentration less than or equal to 500/mL, measured as HPC, is deemed to have an adequate disinfectant residual for purposes of determining compliance.

As stated in the public water supply regulations concerning disinfection and filtration, a public water system using groundwater or surface water as a source and uses chlorine for disinfection must provide the following:

1. A public water system shall use continuous automatic disinfection by chlorination.
2. Provide a minimum free chlorine residual of two-tenths (0.2) milligrams per liter, or ppm, throughout the distribution system measured as described in subsection (2) of 401 KAR 8:150 Section 1.
3. Provide a contact period of at least 30 minutes between the chlorine and the water to allow adequate time for disinfection.
4. Check free chlorine residuals daily at representative points throughout the system.
5. Report the free chlorine residuals monthly.

The Surface Water Treatment Rule (SWTR) establishes two requirements concerning the maintenance of a residual. First, the SWTR requires a detectable residual be maintained throughout the distribution system. Second, a minimum free chlorine residual level of 0.2 mg/L must be maintained as stated in public water supply regulations, 401 KAR 8:150, Section 1(1)(a)2. 

For water systems using chlorine, the minimum requirement in the regulations is to report free chlorine residual; however, for operation and maintenance, the system could, periodically, report total chlorine for comparison of total to free chlorine. Water systems using chloramine must report total chlorine residual and maintain a minimum residual level of 0.5 mg/L throughout the distribution system (401 KAR 8:150 Section 1[1][b]).

Maintaining a minimum disinfectant residual prevents microbial growth in the distribution system. In addition, recording daily free chlorine residual helps the water system with operation and maintenance to detect potential problems. The absence of a detectable disinfectant residual may be caused by a number of factors, including:

1. Insufficient chlorine applied at the treatment plant.
2. Interruption of chlorination.
3. A change in chlorine demand in either the source water or the distribution system.
4. Long standing times and/or long transmission distances.

In the absence of a detectable disinfectant residual in the distribution system, the water system may opt through operation and maintenance to correct the problem through one of the following techniques:

1. Routine flushing.
2. Increasing disinfectant doses at the water system.
3. Cleaning of the pipes (either mechanically by pigging or by the addition of chemicals to dissolve the deposits) in the distribution system and/or storage tanks to remove accumulated debris, which may be exerting a disinfectant demand.
4. Flushing and disinfection of the portions of the distribution system in which a residual is not maintained.
5. Installation of booster disinfection feed facilities within the distribution system.
6. Looking for potential cross-connections.
7. Eliminating dead-end lines.
8. Improving coagulation/flocculation/sedimentation process to reduce total organic carbon that can continue to exert a chlorine demand in the distribution system.

For questions regarding chlorine residuals in the distribution system, contact Frank Hall, supervisor of the Facility Planning and Compliance Section, or a compliance officer in the Drinking Water Branch at 502-564-3410.