Public Works - Water Quality
City water quality technicians conduct tests daily throughout the water system to monitor water quality. Fire hydrants are tested Monday through Friday.
Pump stations are tested on Monday, Wednesday and Friday. Water towers are tested on Tuesdays and Thursdays.
The data provided below are the raw testing results for all water quality data collected and read from testing equipment. These results are monitored throughout the day to identify areas where water quality might be decreasing and flushing could be needed.
Why We Measure Water Usage
Water usage is already measured by the North Texas Municipal Water District and reported to the City of Plano monthly.
The City of Plano is contracted to receive 26.1 billion gallons each water year (August 1 through July 31).
With conservation, the City of Plano strives to stay below that contracted amount to ensure we are using our water resources wisely.
Water Quality Testing
Total Chlorine Residual
Because tap water is not sterile, it is important to maintain a chloramine residual above 0.5 mg/L to prevent harmful bacteria growth in the water distribution system. The maximum residual disinfectant level average must be below 4.0 mg/L.
The chart below shows daily water samples collected by water quality technicians. Daily Residual samples only test for total chlorine residuals. Water Quality samples test for all parameters (total chlorine residual, free chlorine, monochloramine, free ammonia, nitrates, nitrites and total alkalinity).
Maximum Residual Disinfectant Level
Water providers are required to maintain a minimum chlorine disinfection residual level of 0.5 parts per million (ppm) for systems disinfecting with chloramines and an
annual average chlorine disinfection residual level of between 0.5 (ppm) and 4 parts per million (ppm).
Bacteriological Sampling
City water quality technicians take at least 150 samples each month to ensure our water is safe.
While taking samples for bacteriological testing, technicians also check total chlorine residuals.
Water samples are then transported to the North Texas Municipal Water District's accredited laboratory for testing.
Sample results are received the following business day.
Data on this site is updated weekly.
Total Coliform Rule & Monitoring
Total coliforms are a group of related bacteria that are (with few exceptions) not harmful to humans. A variety of bacteria, parasites, and viruses, known as pathogens, can potentially cause health problems if humans ingest them. EPA considers total coliforms a useful indicator of other pathogens for drinking water. The Revised Total Coliform Rule (established by the Environmental Protection Agency) requires public water systems to monitor total coliforms to determine the adequacy of water treatment and the integrity of the water distribution system. No more than 5.0% of samples can test positive for total coliform (TC-positive) in a month.
Bacteriological Sample Results
The graph below shows monthly results for all bacteriological samples. Heavy bacteria and total coliform are not a health threat by themselves since coliforms are naturally present in the environment. Samples with heavy bacteria and total coliform are used to indicate whether other potentially harmful bacteria may be present. Any sample with total coliform present must be re-tested at the same site and both upstream and downstream of the site. While there is not a legal requirement to retest locations where heavy bacteria has been identified, we voluntarily retest those locations also to ensure our water is safe. Fecal coliforms and E. coli are a health threat since these pathogens only come from human and animal fecal waste. Samples positive for fecal coliforms or E. coli result in corrective actions and possibly public notification.
Total Coliform Positive Samples
If a routine bacteria sample tests positive for total coliform, the sample is then tested for E. coli. Three repeat samples are required after a positive total coliform sample occurs: 1) sample from the original location, 2) sample within five houses upstream and 3) sample within five houses downstream. If any of the repeat samples test positive for total coliform, then the sample must be tested for E. coli. If any of the repeat samples test positive for E. coli, another set of repeat sampling is required, unless an assessment is triggered. For more information on assessments, refer to the quick reference guide. The table below lists the City of Plano's positive total coliform samples from July 2011 to present. All positive total coliform samples are available through TCEQ's Drinking Water Watch database.
Lead and Copper Rule
The Lead and Copper Rule protects public health by minimizing lead and copper levels in drinking water, primarily by reducing corrosion of plumbing materials. This rule applies to all community water systems, including the City of Plano.
Sampling is accomplished through a partnership with homeowners and residents. One hundred
(100) sites in the City of Plano are approved by the Texas Commission on Environmental Quality (TCEQ) for monitoring. Fifty (50) sites are selected annually and homeowners submit samples between June 1 and September 30. City of Plano staff collect samples and deliver them to a lab accredited by the State of Texas under the National Environmental Laboratory Accreditation Program.
The data on this site is updated annually once lead and copper sampling is completed and results are available.
Lead Action Level
The lead action level is 0.015 milligrams per liter (mg/L). The action level is exceeded if the "90th percentile" lead level exceeds 0.015 mg/L in any monitoring period. The 90th percentile lead level is exceeded when more than 10% of tap water samples have a concentration over the action level.
The chart displays the lead concentrations at sites sampled for the selected year. Sites with no value indicate lead concentrations were below the detectable reporting value of 0.0005 mg/L. Only 50 of the TCEQ approved 100 sites are sampled each year. Sample IDs stay the same, but locations change depending on homeowner availability.
Copper Action Level
The copper action level is 1.3 mg/L. The action level is exceeded if the concentration of copper in more than 10% of tap water samples collected during any monitoring period is greater than 1.3 mg/L.
The chart displays the copper concentrations at sites sampled for the selected year. Only 50 of the TCEQ approved 100 sites are sampled each year. Sample IDs stay the same, but locations change depending on homeowner availability.
Total Trihalomethanes
Disinfection byproducts (DBPs) are chemicals that form, during drinking water treatment and distribution, when naturally occurring organic matter reacts with chlorine or other disinfectants used to kill pathogenic organisms. The EPA has determined that Total Trihalomethanes (TTHM) are one of the chemical classes that must be monitored.
The Texas Commission on Environmental Quality (TCEQ) uses contract samplers to collect all TTHM samples used for compliance. TTHM samples are analyzed by the Lower Colorado River Authority or the Department of State Health Services and results are provided to the city and published online at TCEQ's Drinking Water Watch page. To read more about disinfection byproducts, visit TCEQ's webpage on DPBs.
Data is updated quarterly as sample results are received.
TTHM Results
To comply with the Stage 2 Disinfection Byproduct Rule, the rolling quarterly average at each sample site must be below .080 mg/L (80 ug/L).
To view sample results at each location, click "View Source Data" below the chart.
TTHM Chlorine Maintenance Special Samples
The North Texas Municipal Water District conducts chlorine maintenance throughout the water delivery system in February/March each year. Starting in 2018, the City of Plano began collecting samples to analyze disinfection byproducts during this time period.
Samples are collected from the same 12 sites normally sampled plus the four pump stations. In 2019, Plano started conducting special sampling twice during the maintenance period. In 2020, samples were collected from the inlet and outlet locations at all four pump stations to monitor changes inside tanks. There was an error with the first set of samples collected at the Out location of Custer Pump Station and the In location of Stadium Pump Station. The chart below shows the received TTHM special sample results by location from both sample dates.
Haloacetic Acids (HAA5)
Disinfection byproducts (DBPs) are chemicals that form, during drinking water treatment and distribution, when naturally occurring organic matter reacts with chlorine or other disinfectants used to kill pathogenic organisms. The EPA has determined that Haloacetic Acids (HAA5) are one of the chemical classes that must be monitored.
The Texas Commission on Environmental Quality (TCEQ) uses contract samplers to collect all HAA5 samples used for compliance. HAA5 samples are analyzed by the Lower Colorado River Authority or the Department of State Health Services and results are provided to the city and published online at TCEQ's Drinking Water Watch page. To read more about disinfection byproducts, visit TCEQ's webpage on DPBs.
Data is updated quarterly as sample results are received.
HAA5 Results
To comply with the Stage 2 Disinfection Byproduct Rule, the rolling quarterly average for HAA5 at each sample site must be below .060 mg/L (60 ug/L).
To view sample results at each location, click "View Source Data" below the chart.
HAA5 Chlorine Maintenance Special Samples
The North Texas Municipal Water District conducts chlorine maintenance throughout the water delivery system in March each year. Starting in 2018, the City of Plano began collecting samples to analyze disinfection byproducts during this time period. Samples are collected from the same 12 sites normally sampled plus the four pump stations. In 2019, Plano started conducting special sampling twice during the maintenance period. In 2020, samples were collected from the inlet and outlet locations at all four pump stations to monitor changes inside tanks.
The chart below shows the HAA5 special sample results by location from both sample dates.
HAA5 / TTHM Regulated Contaminants
Range of Levels Detected includes the quarterly samples collected by TCEQ. Special samples were collected during the month of March in 2020 during the chlorine
maintenance period and therefore are not included in the table above. The results for TTHMs ranged from 41 to 93 mg/L and HAA5 from 19 to 35 mg/L.
