Water Information

Notice To At-Risk Populations
Some people may be more vulnerable to contaminants in drinking water than the general population. Immune-compromised persons such as persons with cancer undergoing chemotherapy, persons who have undergone organ transplants, people with HIV / AIDS or other immune system disorders, some elderly, and infants can be particularly at risk from infections. These people should seek advice about drinking water from their health care providers. The U.S. Environmental Protection Agency (EPA) / Centers for Disease Control and Prevention (CDC) guidelines on appropriate means to lessen the risk of infection by Cryptosporidium and other microbial contaminants are available from the Safe Drinking Water Hotline at (800) 426-4971.

Our Drinking Water Meets or Exceeds All EPA Drinking Water Requirements
This report is a summary of the quality of the water we provide our customers. The analysis was made by using data from the most recent U.S. Environmental Protection Agency (EPA) required tests and is presented in the attached pages. We hope this information helps you become more knowledgeable about what's in your drinking water.

Water Sources
The sources of drinking water (both tap water and bottled) include rivers, lakes, streams, ponds, reservoirs, springs, and wells. As water travels over the land's surface or through the ground, it dissolves naturally occurring minerals and, in some cases, radioactive material, and can pick up substances resulting from the presence of animals or human activity. Contaminants that may be in untreated water include microbes, inorganic contaminants, pesticides, herbicides, organic chemical contaminants, and radioactive contaminants.

Where Do We Get Our Water?
Most of the water we treat is from city-owned Lake Randell, located to the northwest of Denison between U.S. 75 and Lake Texoma. The supply for Lake Randell is supplemented by water transferred from Lake Texoma. Almost all our customers are served by surface water from these 2 lakes. Our customers in the area of Grayson County Airport are served by a combination of surface water and ground water from wells the City operates on the Grayson County Airport property. These wells produce water from the Trinity / Paluxy aquifer formation. The Texas Commission on Environmental Quality (TCEQ) completed an assessment of our source water and results indicate that some of sources are susceptible to certain contaminants. The sampling requirements for our water system are based on this susceptibility and previous sample data. Any detection of those contaminants will be found in this report. For more information on source water assessments and protection efforts at our system, please contact us.

All Drinking Water May Contain Contaminants
When drinking water meets federal standards there may not be any health related benefits to purchasing bottled water or point of use devices. All drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants. The presence of these contaminants does not necessarily indicate that water poses a health risk More information about contaminants and potential health effects may be obtained by calling USEPA's Safe Drinking Water Hotline at (800) 426-4791.

En Espanol
Este reporte incluye informacion importante sobre el agua para tomar. Si tiene preguntas o'discusiones sobre este reporte en espanol, favor de llamar at tel. (903) 464-4481 par hablar con una persona bilinque en Espanol.

How Is Water Treated?
The City of Denison uses the latest techniques and equipment to consistently produce superior quality drinking water. Utilizing conventional treatment processes, we produce an average 4 to 9 million gallons of water per day for our customers. The process is divided into 4 separate steps to achieve the desired quality product mandated by the TCEQ and USEPA. Coagulation, settling, filtration, and disinfection are considered the treatment of choice for surface water in the United States. Coagulation is chemically and mechanically changing the raw water to remove the majority of larger solids. In settling the water, the finer particles have time to be removed before continuing on to filtration to remove microscopic particles. Disinfection is done with chloramine compounds before leaving the water plant and entering the distribution system. The water is sampled and tested throughout the treatment plant. Sampling is performed to make sure the processes are working and that the water is safe before it leaves the plant. The City of Denison tests 25 sites per month in the distribution system and reports results to TCEQ and USEPA. All employees involved in treating, collecting samples, and making repairs to the distribution system are certified by TCEQ through training and testing.

Secondary Constituents
Many constituents (such as calcium, sodium, or iron) which are often found in drinking water, can cause taste, color and odor problems. The taste and odor constituents are called secondary constituents and are regulated by the State of Texas, not the EPA. These constituents are not causes for health concern. Therefore, secondary standards are not required to be reported in this document but they may greatly affect the appearance and taste of your water.

Unregulated Contaminate Monitoring Rule
We participated in gathering data under the UCMR in order to assist EPA in determining the occurrence of possible drinking water contaminants. If any unregulated contaminants were detected they are shown in the tables elsewhere in the report.

  • NTU - Nephelometric Turbidity Units - This is the unit used to measure water turbidity
  • MCLG - Maximum Contaminant Level Goal - The level of a contaminant in drinking water below which there is no known or expected health risk. MCLG's allow for a margin of safety.
  • MCL - Maximum Contaminant Level - The highest permissible level of a contaminant that is allowed in drinking water. MCL's are set as close to the MCLG's as feasible using the best available treatment technology.
  • AL - Action Level - The concentration of a contaminant which, if exceeded, trigger treatment or other requirements that a water system must follow.
  • Turbidity - A measure of the cloudiness of water. We monitor it because it is a good indicator of the effectiveness of our filtration system.
  • Treatment Technique - A required process intended to reduce the level of a contaminant in drinking water.
  • ppm - Parts per million. One part per million equals 1 packet of artificial sweetener sprinkled into 250 gallons of iced tea.
  • ppb - Parts per billion - One part per billion is equal to 1 packet of artificial sweetener added to an Olympic size swimming pool.
  • ppt - Parts per trillion, or nanograms per liter
  • ppq - Parts per quadrillion, picograms per liter
  • pci / l - Picocuries per liter is a measure of radioactivity in water.
  • MFL - million fibers per liter (a measure for asbestos)
  • MRDL - Maximum Residual Disinfectant Level - The highest level of disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.
  • MRLDG - Maximum Residual Disinfectant Level Goal - The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contamination.