IRWD water quality results for 2024
How to read this Water Quality Report This report lists results from drinking water quality assessments in 2024. The following charts show drinking water quality results for all of last year. Data includes the range of detection, the typical sources of contaminants for a variety of regulated elements and how they compare to water quality standards. To provide our customers more insight, the tables include secondary standards that are for aesthetic qualities of the water, such as water hardness, pH, color, corrosivity and more. The legend at right defines the acronyms, explains water quality standards and goals, and outlines how substances are measured. Your water has been tested for many more chemicals than are listed in this report, including metals, pesticides and volatile organic compounds. If you don’t see something on the chart, don’t worry. That does not mean we didn’t test for it. Rather, if we test for a chemical and don’t find it — or if its concentration is too low to be distinguishable — we don’t list it. For example, we tested for mercury. We didn’t find it. So we didn’t list it.
Chart legend What are water quality standards?
Drinking water standards established by U.S. EPA and DDW set limits for substances that may affect consumer health or aesthetic qualities of drinking water. The charts in this report show the following types of water quality standards: • Maximum Contaminant Level (MCL): The highest level of a contaminant that is allowed in drinking water. Primary MCLs are set as close to the PHGs (or MCLGs) as is economically and technologically feasible. • Maximum Residual Disinfectant Level (MRDL): The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants. • Secondary MCLs are set to protect the odor, taste and appearance of drinking water. • Primary Drinking Water Standard: MCLs for contaminants that affect health along with their monitoring and reporting requirements and water treatment requirements. • Regulatory Action Level (AL): The concentration of a contaminant, which, if exceeded, triggers treatment or other requirements that a water system must follow. What is a water quality goal? In addition to mandatory water quality standards, U.S. EPA and DDW have set voluntary water quality goals for some contaminants. Water quality goals are often set at such low levels that they are not achievable in practice and are not directly measurable. Nevertheless, these goals provide useful guide posts and direction for water management practices. The charts in this report includes three types of water quality goals: • Maximum Contaminant Level Goal (MCLG): The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs are set by U.S. EPA. • Maximum Residual Disinfectant Level Goal (MRDLG): 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 contaminants. • Public Health Goal (PHG): The level of a contaminant in drinking water below which there is no known or expected risk to health. PHGs are set by the California Environmental Protection Agency. How are contaminants measured? Water is sampled and tested throughout the year. Contaminants are measured in:
• Parts per million (ppm) or milligrams per liter (mg/L) • Parts per billion (ppb) or micrograms per liter (μg/L) • Parts per trillion (ppt) or nanograms per liter (ng/L)
2024 water quality results
MCL (MRDL/MRDLG)
Average amount 24.1*** 10.0***
MCL violation?
Disinfection byproducts Total Trihalomethanes (ppb) Haloacetic Acids (five) (ppb) Chlorine residual (ppm) Aesthetic quality Color (color units)
Range of detections
Typical source of contaminant Byproducts of chlorine disinfection Byproducts of chlorine disinfection Disinfectant added for treatment
80 60
9.1 - 44.2 4.1 - 19.6 ND - 3.9
No No No No No No
(4.0 / 4)
1.9
15*
<3 0.1 <1
ND - 4
Erosion of natural deposits Erosion of natural deposits Erosion of natural deposits
Turbidity (NTU)
5* 3*
ND - 6.9
Odor (threshold odor number)
ND - 4
Other Fluoride (mg/L)
2/0.8**
0.54
0.18 - 0.80
No
Erosion of natural deposits, water treatment
Twelve locations in the distribution system are tested quarterly for total trihalomethanes and haloacetic acids; 60 locations are tested monthly for color and odor, and weekly for chlorine residual and turbidity. MRDL = Maximum Residual Disinfectant Level; MRDLG = Maximum Residual Disinfectant Level Goal *Contaminant is regulated by a secondary standard; **MCL/Optimum Level for our climate; *** Highest running annual average at any individual sample location Lead and copper action levels at residential taps Action Level (AL) Public Health Goal (PHG) 90th percentile value Sites exceeding AL / number of sites AL violation?
Typical source of contaminant
Copper (ppm)
1.3
0.3 0.2
0.1908
0/72 0/72
No No
Corrosion of household plumbing
Lead (ppb) Corrosion of household plumbing The most recent lead and copper at-the-tap samples were collected from 72 residences in 2022. Lead was detected in zero homes and copper was detected in 26 homes, but none of the samples for lead and copper exceeded the respective regulatory Action Level (AL). A regulatory Action Level is the concentration of a contaminant which, if exceeded in more than 10% of samples, triggers treatment or other requirements that a water system must follow. Unregulated chemicals requiring monitoring in the distribution system Chemical Notification level PHG (MCLG) Average local and imported Range of detections Most recent sampling date Germanium, total (ppb) N/A N/A 0.82 ND - 1.1 2020 Manganese, total (ppb) MCL = 50* N/A 1.6 0.8 - 2.2 2020 *Contaminant is regulated by a secondary standard. 15 <5
IRWD Water Quality Report 2025 | Page 7
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