While your drinking water meets EPA’s standard for arsenic and is less than the MCL, it does contain low levels of arsenic. EPA’s standard balances the current understanding of arsenic’s possible health effects against the costs of removing arsenic from drinking water. EPA continues to research the health effects of low levels of arsenic, which is a mineral known to cause cancer in humans at high concentrations and is linked to other health effects such as skin damage and circulatory problems.
If you are installing a water softener, aquarium, pool, home brewing beer, or require certain water quality for your individual operation, please use this chart for your setup needs.
Locate where you are on the map and use the corresponding chart below, or on the interactive map, to answer your water quality needs.
Water Quality by Zone
| Zone 1 | Zone 2 | Zone 3 | Zone 4 | Zone 5 | System Average | |
| Alkalinity (mg/L) | 86.50 | 95.25 | 174.00 | 192.00 | 210.00 | 151.55 |
| CaCO3 Calcium Carbonate (Alkalinity) (mg/L) | 130.00 | 92.00 | 126.80 | 86.83 | 120.00 | 111.13 |
| Calcium (mg/L) | 20.00 | 33.67 | 50.40 | 34.50 | 47.00 | 37.11 |
| Chloride (mg/L) | 13.75 | 17.30 | 18.57 | 14.15 | 7.20 | 14.19 |
| Fluoride* (Naturally Occurring) (mg/L) | 0.26 | 0.24 | 0.39 | 0.46 | 0.44 | 0.36 |
| Hardness (Grains Per Gallon) | 9.36 | 8.05 | 8.70 | 6.70 | 10.16 | 8.59 |
| Hardness (mg/L) | 113.50 | 118.00 | 126.80 | 86.83 | 150.00 | 119.03 |
| Iron (mg/L) | 0.23 | 0.04 | 0.00 | 0.00 | 0.00 | 0.05 |
| Magnesium (mg/L) | 6.45 | 5.83 | 9.26 | 5.72 | 8.00 | 7.05 |
| Manganese (mg/L) | 0.00 | 0.00 | 0.01 | 0.02 | 0.00 | 0.01 |
| pH (units 0-14) | 7.75 | 7.95 | 7.92 | 8.08 | 8.00 | 7.94 |
| Sodium (mg/L) | 16.00 | 19.00 | 38.40 | 59.00 | 79.00 | 42.28 |
| Sulfate (mg/L) | 67.00 | 48.50 | 47.25 | 47.17 | 71.00 | 56.18 |
| Sulfide (mg/L) | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| Sulfur (mg/L) | 22.00 | 10.73 | 14.15 | 15.75 | 31.47 | 18.82 |
| TDS (Total Dissolved Solids) (mg/L) | 210.00 | 235.00 | 285.00 | 324.00 | 360.00 | 282.80 |
* The City does not add fluoride to our water; any fluoride detected is naturally present in our groundwater sources.
A hard copy report of Meridian water quality can be picked up at the Meridian Water Division and Meridian City Hall.
Meridian Water Quality Data
The City routinely monitors your drinking water for contaminants in accordance with federal, State, and local standards. The State of Idaho requires us to monitor for certain contaminants less than once per year because the concentrations of these contaminants are generally stable, not expected to vary from year to year, or the system is not considered vulnerable to this type of contamination. Therefore, some of our data, though representative, may be more than one year old. These tables show the results of monitoring for the period from January 1st to December 31st, 2024, unless otherwise noted. For more information about this report or any questions relating to your drinking water, please email water@meridiancity.org or call 208-888-5242.
Inorganic Substances
Results Reported in Milligrams per Liter (mg/L)
| Substance | Violation | MCL | MCLG | Lo Level Detected | Hi Level Detected | Test Date | Likely Source of Contamination | ||
|---|---|---|---|---|---|---|---|---|---|
| Arsenic (mg/L) | N | 0.01 | 0 | Not Detected | 0.0013 | September (2024) | Erosion of natural deposits; runoff from orchards | ||
| Barium (mg/L) | N | 2 | 2 | Not Detected | 0.068 | September (2024) | Erosion of natural deposits | ||
| Chromium (mg/L) | N | 0.1 | 0.1 | Not Detected | 0.0014 | August (2023)** | Discharge from steel and pump mills; Erosion of natural deposits | ||
| Fluoride (mg/L) | N | 4 | 4 | 0.18 | 0.27 | September (2024) | Erosion of natural deposits; Discharges from fertilizer and aluminium factories | ||
| Nitrate (as Nitrogen) (mg/L) | N | 10 | 10 | Not Detected | 4 | March (2024) | Erosion of natural deposits | ||
Semivolatile Organic Compounds
Results Reported in Milligrams per Liter (mg/L)
| Substance | Violation | MCL | MCLG | Lo Level Detected | Hi Level Detected | Test Date | Likely Source of Contamination |
|---|---|---|---|---|---|---|---|
| Atrazine (mg/L) | N | 0.003 | 0.003 | Not Detected | 0.00018 | September (2024) | Runoff from herbicide use on row crops |
| Di(2-Ethylhexyl) Adipate (mg/L) | N | 0.4 | 0.4 | Not Detected | 0.00075 | August (2023)** | Discharge from chemical factories |
Radionuclides
Results Reported in picocuries per Liter (pCl/L) or Milligrams per Liter (mg/L)
| Substance | Violation | MCL | MCLG | Lo Level Detected | Hi Level Detected | Test Date | Likely Source of Contamination |
|---|---|---|---|---|---|---|---|
| Gross Alpha Particle Activity (pCi/L) | N | 15 | 0 | Not Detected | 12 | October (2024) | Erosion of natural deposits |
| Uranium (mg/L) | N | 0.030 | 0 | Not Detected | 0.029 | October (2024) | Erosion of natural deposits |
Disinfection By-Products
Results Reported in Milligrams per Liter (mg/L)
| Substance | Violation | MCL | MCLG | Lo Level Detected | Hi Level Detected | 2023 Test Date | Likely Source of Contamination |
|---|---|---|---|---|---|---|---|
| Haloacetic Acids (5) (HAA5s) | N | 0.060 | N/A | Not Detected | Not Detected | October (2024) | By-product of drinking water disinfection |
| Total Trihalomethanes (TTHMs) | N | 0.080 | N/A | Not Detected | 0.011 | July (2024) | By-product of drinking water disinfection |
Disinfection
| Disinfectant | Violation | MCL | MCLG | Avg. Level Detected | Hi Level Detected | Test Date | Likely Source of Contamination |
| Chlorine Residual | N | 4.000 | 4 | 1.2 | 1.89 | July (2024) | Water additive used to control microbes |
Microbiological
| Substance | MCL | MCLG | Highest % Positive in a Month | Total Number Positive for 2024 | Likely source of contaminant |
|---|---|---|---|---|---|
| Total Coliform Bacteria | <5% | 0 | 0.00% | 0 | Naturally present in the environment |
Lead and Copper
| Substance | Violation | MCLG | Action Level | Results 90th Percentile | Samples Collected | Samples Above Action Level | Test Date | Likely Source of Contamination |
|---|---|---|---|---|---|---|---|---|
| Copper (mg/L or ppb) | N | 1.3 | 1.3 | 0.1 | 123 | 0 | June (2024) | Corrosion of household plumbing systems; erosion of natural deposits |
| Lead (ug/L or ppb) | N | 0 | 15 | 2 | 123 | 1 | November (2024) | Corrosion of household plumbing systems; erosion of natural deposits |
Unregulated Substances
The Unregulated Contaminant Monitoring Rule (UCMR), part of the Safe Drinking Water Act, requires the EPA and water systems to assess the occurrence of up to 30 unregulated substances in drinking water every five years. This occurrence data helps the EPA determine whether future regulation is warranted.
| Substance | Year | Unit | Lo Level | Hi Level | Average |
| Lithium | 2024 | ppb | Not Detected | 99.5 | 28.1 |
| Perfluorohexanesulfonic Acid (PFHxS) | 2024 | ppt | Not Detected | 3.7 | 0.16 |
** Due every three years; next due in 2026.
Definitions to help understand abbreviations used in this report
(AL) Action Level: The concentration of a contaminant that, if exceeded, triggers treatment or other requirements that a community water system shall follow.
(HAA) Haloacetic Acids: By-products created when disinfectants used to treat water react with organic and inorganic material in source water.
(MCL) Maximum Contaminant Level: The highest level of 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 risk to health. MCLGs allow a margin of safety.
(ppb) Parts per billion
(ppt) Parts per trillion
Primary Standards: Federal drinking water regulations for substances that are health-related. Water suppliers must meet all primary drinking water standards.
Secondary Standards: Federal drinking water measurements for substances that do not have an impact on health. These reflect aesthetic qualities such as taste, odor, and appearance. Secondary standards are recommendations, not mandates.
(THM) Trihalomethanes: Chemical compounds that can be formed when water is disinfected with chlorine.
Information about drinking water
In order to ensure that tap water is safe to drink, the United States Environmental Protection Agency (EPA) prescribes regulations that limit the concentration of certain contaminants in water provided by public water systems. The Food and Drug Administration regulations establish limits for contaminants in bottled water. Drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants. The presence of contaminants does not necessarily indicate that water poses a health risk.
More information about contaminants in tap water and potential health effects can be obtained by calling the Environmental Protection Agency’s Safe Drinking Water Hotline (800-426-4791). Information on bottled water can be obtained from the Food and Drug Administration ».
Sources of drinking water (both tap water and bottled water) include rivers, lakes, streams, ponds, reservoirs, springs, and wells. As water travels over the surface of the land or through the ground, it dissolves naturally-occurring minerals and, in some cases, radioactive material. The water can pick up substances resulting from the presence of animals or from human activity. Contaminants that may be present in source water include the following:
- Microbial contaminants, such as viruses and bacteria that may be from sewage treatment plants, septic systems, agricultural livestock operations, or wildlife.
- Inorganic contaminants, such as salts and metals, that can be naturally-occurring or result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining, or farming.
- Pesticides and herbicides that may come from a variety of sources such as agriculture, urban storm water runoff, and residential uses.
- Organic chemical contaminants, including synthetic and volatile organics that are by-products of industrial processes and petroleum production, and can also come from gas stations, urban storm water runoff and septic systems.
- Radioactive contaminants that can be naturally-occurring or can be the result of oil and gas production and mining activities.
Additional Health Information
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, persons 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 healthcare providers.
Lead is a naturally occurring element found in small amounts of the Earth's crust. Elevated levels of lead in humans can cause serious health problems, especially for pregnant women and young children. Lead occurrence in drinking water is primarily from materials and components associated with water service lines and home plumbing fixtures. Lead can enter drinking water through corrosion of plumbing materials, especially where the water has high acidity or low mineral content.
Meridian's water source wells contain no traces of lead.
Meridian proactively samples for and monitors concentrations of lead in our drinking water. Throughout the City, samples are taken regularly at random houses constructed during the time frames that lead was potentially used in plumbing. Results are shared with homeowners and reported to the Idaho Department of Environmental Quality (IDEQ). Looking forward, we will continue to sample and monitor for lead.
Although the City of Meridian is responsible for providing high-quality drinking water, it cannot control the variety of materials used in plumbing components. If you reside in a residence where you feel lead plumbing components have been used, minimize your exposure by flushing your tap for 30 seconds to 2 minutes before drinking or using it for cooking. If you are concerned about lead in your water, you may wish to have your water tested. Information on lead in drinking water, testing methods, and steps you can take to minimize exposure are available from the Safe Drinking Water Hotline or the EPA.
Nitrate in drinking water at levels above 10 ppm is a health risk for infants less than six months of age. High nitrate levels in drinking water can cause blue baby syndrome. Nitrate levels may rise quickly for short periods because of rainfall or agricultural activity. If you are caring for an infant and detect nitrate levels above 5 ppm, you should ask for advice from your healthcare provider.