EPA has established National Primary Drinking Water Regulations (NPDWRs) that set mandatory water quality standards for drinking water contaminants. These are enforceable standards called “maximum contaminant levels” (MCLs) which are established to protect the public against consumption of drinking water contaminants that present a risk to human health.
Regulated Contaminants — As required by the Oklahoma Department of Environmental Quality, the City of Tulsa tests for a total of 34 different regulated contaminants on a yearly basis — this includes more than 48,000 water quality tests performed in 2024. The City of Tulsa is required to report any detectable regulated contaminant, even if levels found were well below the maximum contaminant level. The attached table lists all regulated contaminants that were detected during water quality monitoring in 2024.
Secondary Contaminants — In addition, EPA has established National Secondary Drinking Water Regulations (NSDWRs) that set non-mandatory water quality standards as guidelines for aesthetic considerations such as taste, color, and odor.
Unregulated Contaminants — The City of Tulsa participates in Unregulated Contaminant Monitoring every five years. This monitoring helps advance the science of safe drinking water by testing water for contaminants that are not regulated by National Primary Drinking Water Regulations but are known or anticipated to occur at public water systems. This monitoring assists EPA in determining which contaminants may warrant monitoring under the Safe Drinking Water Act.
This table shows data for samples collected during 2024 (unless otherwise noted). Analyses made by professionals after water treatment showed the levels of all contaminants found were much less than the maximum allowable levels established by the state and federal regulatory agencies.
AL = Action Level: The concentration of a contaminant which, if exceeded, triggers a treatment or other requirement which a water system must follow.
MCL = Maximum Contaminant Level: The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to the MCLGs as feasible using the best available treatment technology.
MCLG = Maximum Contaminant Level Goal: The level of contaminant in drinking water below which there is no known or expected health risk.
MRDL = Maximum Residual Disinfectant Level: The highest level of disinfectant allowed in drinking water.
LRAA = Locational Running Annual Average: The average of the last 12 months or last 4 quarters for each monitoring location. Calculated LRAA might include results from 2023.
RAA = Running Annual Average: The average of the last 12 months or last 4 quarters. Calculated RAA might include results from 2023.
NTU = Nephelometric Turbidity Unit
TT = Treatment Technique: A required process intended to reduce the level of a contaminant in drinking water.
su = Standard Units
ppm: parts per million or milligrams per liter (mg/L)
ppb: parts per billion or micrograms per liter (µg/L)
CFU: Colony Forming Units
pCi/L: picocuries per liter (a measure of radioactivity)
mrem = millirem: The unit of radiation dose.
** The U.S. Public Health Service recommends a fluoride concentration of 0.7 mg/L (parts per million [ppm]) to maintain dental cavity prevention benefits and reduce the risk of dental fluorosis. Tulsa ordinances require the maximum content of fluoride to be no more than 0.7 ppm.
*** Compliance based on running annual average of TOC removal ratios.
**** The MCL for beta particles is 4 mrem*/year. EPA considers 50 pCi/L to be the level of concern for beta particles.
| Regulated Contaminants | Unit | Ideal Goal (MCLG*) | Highest Level Allowed (MCL*) | Our Tap Water | Compliance | Likely Source of Contaminants | ||
| Inorganic Compounds | ||||||||
| Atrazine | ppb* | 3 | 3 | Highest Running Annual Average: 0.360 | Yes | Runoff from herbicide used on row crops. | ||
| Range detected: 0.217 - 0.511 | ||||||||
| Barium | ppm* | 2 | 2 | Highest level: 0.072 | Yes | Naturally present in the environment, drilling waste, metal refineries. | ||
| Range detected: 0.036 - 0.072 | ||||||||
| Chlorite | ppm | 0.8 | 1 | Highest level: 0.342 | Yes | By-product of drinking water disinfection. | ||
| Range detected: 0.076 - 0.342 | ||||||||
| Copper | ppm | 1.3 | 1.3 (AL*) | 90th percentile = 0.312, 0 sites above AL | Yes | Corrosion of household plumbing systems, erosion of natural deposits, leaching from wood preservatives. | ||
| Range detected: 0 - 0.550 | ||||||||
| Fluoride | ppm | 4 | 4 | Average detected: 0.69 ** | Yes | Erosion of natural deposits, water additive which promotes strong teeth, discharge from fertilizer and aluminum factories. | ||
| Range detected: 0.26- 0.85 | ||||||||
| Lead | ppb | 0 | 15 (AL*) | 90th percentile = 1.67, 1 site above AL | Yes | Corrosion of household plumbing systems, erosion of natural deposits. | ||
| Range detected: 0 - 32.9 | ||||||||
| Nitrate/Nitrite Total | ppm | 10 / 1 | Nitrate=10 Nitrite=1 | Highest level: 0.28 | Yes | Naturally occurring, fertilizers, sewage treatment plants, leaching from septic tanks, erosion of natural deposits. | ||
| Range detected: 0 - 0.28 | ||||||||
| Disinfection Residual | ||||||||
| Chloramine as Chlorine | ppm | 4 | 4.0 (MRDL*) | Highest Running Annual Average: 2.5 | Yes | Water additive used to control microbes. | ||
| Range detected: 1.6 - 3.3 | ||||||||
| Disinfection By-Procucts | ||||||||
| Total Trihalomethanes | ppb | N/A | 80 (LRAA*) | Highest Locational Running Annal Average (LRAA): 36 | Yes | By-product of drinking water disinfection. | ||
| Range detected: 19 - 52 | ||||||||
| Haloacetic Acids | ppb | N/A | 60 (LRAA*) | Highest Locational Running Annual Average (LRAA): 15 | Yes | By-product of drinking water disinfection. | ||
| Range detected: 4.4 - 24 | ||||||||
| Precursor Removal | ||||||||
| Total Organic Carbon | N/A | N/A | TT* = Ratio must be greater than or equal to 1.00 for compliance | Running Annual Average 1.06 | Yes | Naturally found in the environment. | ||
| Lowest Month for Removal: February 0.92 | ||||||||
| Microbiological | ||||||||
| Coliform Bacteria | CFU* | 0 | Presence of Coliform bacteria in < 5% of samples | Month having the highest % positive: September | Yes | Naturally present in the environment. | ||
| 3 positive Coliform results in 199 samples: 1.51% | ||||||||
| Clarity | ||||||||
| Turbidity | NTU* | N/A | TT*= less than 0.3 NTU 95 percent of the time. | Lowest monthly % of samples with < 0.3 NTU: 100% | Yes | Soil runoff. | ||
| Highest single reading: 0.10 | ||||||||
| Radiological: Most recent testing in December 2022 | ||||||||
| Gross Alpha | pCi/L* | 0 | 15 | < 3.00 | Yes | Erosion of natural deposits. | ||
| Gross Beta | pCi/L | 0 | 50 *** | <4.00 | Yes | Decay of natural and man-made deposits. | ||
| Radium 226 | pCi/L | 0 | 5 (Combined Total) | < 1.00 | Yes | Erosion of natural deposits. | ||
Radium 228 |
pCi/L | 0 | < 1.00 | Yes | Erosion of natural deposits. | |||
| Uranium Total | ppb | 0 | 30 | < 1.00 | Yes | Erosion of natural deposits. | ||
| Secondary Contaminants | Recommended Level (Non-Health Based Standards) | Likely Source of Contaminants | ||||||
| Chloride | ppm | 250 | Average detected: 14.5 | Naturally present, brine from oilfield operations. | ||||
| Range detected: 11.3 - 21.4 | ||||||||
| pH | su | 6.5 - 8.5 | Range detected: 7.6 - 8.5 | Measure of acidity. Naturally present, adjusted in drinking water treatment. | ||||
| Sulfate | ppm | 250 | Average detected: 25.2 | Naturally present in the environment. | ||||
| Range detected: 4.05 - 62.8 | ||||||||
| Other Required Monitoring | Unit | Recommended Level | Likely Source of Contaminants | |||||
| Cryptosporidium | Second round of monitoring (over 48 month duration) was completed in 2017. Detections were found in source water only and were not detected at levels of concern; Cryptosporidium is a microbial pathogen found in surface water throughout the U.S. Although filtration removes cryptosporidium, the most commonly-used filtration methods cannot guarantee 100 percent removal. Our monitoring indicates the presence of these organisms in our source water. Current test methods do not allow us to determine if the organisms are dead or if they are capable of causing disease. Ingestion of cryptosporidium may cause cryptosporidiosis, an abdominal infection. Symptoms of infection include nausea, diarrhea, and abdominal cramps. Most healthy individuals can overcome the disease within a few weeks. However, immuno-compromised people are at greater risk of developing life-threatening illness. We encourage immuno-compromised individuals to consult their doctor regarding appropriate precautions to take to avoid infection. Cryptosporidium must be ingested to cause disease, and it may be spread through means other than drinking water. | |||||||
| Sodium | ppm | Standard has not been established. | Average detected: 10.7 | Naturally occurring, urban stormwater runoff or discharge from sewage treatment plants. | ||||
| Range detected: 8.41 - 14.1 | ||||||||
| UCMR5 Monitoring: The City of Tulsa has completed the Unregulated Contaminant Monitoring (UCMR5) in 2023, which required monitoring for Lithium and 29 Per- and Polyfluoroalkyl Substances (PFAS). Unregulated contaminants are those for which EPA has not established drinking water standards. The purpose of unregulated contaminant monitoring is to assist EPA in determining the occurrence of unregulated contaminants in drinking water and whether future regulation is warranted. Results indicate no detectable levels of PFAS and Lithium present in drinking water. | ||||||||
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