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Inorganic Contaminants in Drinking Water

All water contains inorganic compounds unless it is distilled. On this page we cover common inorganic contaminants—arsenic, fluoride, nitrate and nitrite—and their health effects. Plus public water systems’ requirements for monitoring and sampling, maximum contaminant levels, and treatment options.

On this page:

Common Inorganic Contaminants

Arsenic                                                                                                                     

Maximum Contaminant Level (MCL): 0.010 milligrams per liter (mg/L)

Health Effects

An arsenic MCL exceedance is not an emergency. However, some people who drink water containing arsenic in excess of the MCL over many years could experience skin damage or problems with their circulatory system and may have an increased risk of getting cancer.

Systems that exceed the MCL must identify options to reduce the arsenic levels in their treated water.

Treatment Options

Treatment options include precipitation, adsorption, ion exchange, and reverse osmosis. For more detailed information about treatment options see Environmental Protection Agency content:

Fluoride                                                                                                             

MCL: 4.0 mg/L

Secondary maximum contaminant level: 2.0 mg/L. Find more information about these contaminants.

Health Effects

A fluoride MCL exceedance is not an emergency. However, some people who drink water containing fluoride greater than the MCL over many years could get bone disease, including pain and tenderness of the bones.

Fluoride in drinking water at half the MCL or more may cause mottling of children’s teeth, usually in children less than nine years old. Mottling, also known as dental fluorosis, may include brown staining or pitting of the teeth, and occurs only in developing teeth before they erupt from the gums.

Treatment Options

Treatment options include adsorption, ion exchange, and reverse osmosis. Find detailed information from EPA about treatment options at:

Nitrate and Nitrite            

Nitrate MCL: 10 mg/L

Nitrite MCL:   1 mg/L

Health Effects

Nitrate and nitrite MCL exceedances are an immediate health risk, especially to infants. Infants below the age of six months who drink water containing nitrate or nitrite in levels greater than the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue baby syndrome.

A child under the age of six months must be given an alternative water supply for any consumption. Boiling the affected water is not an effective treatment for nitrate or nitrite removal. The lab that analyzed the samples and TCEQ will contact the PWS if it exceeds the MCL for nitrate or nitrite.

What to Do in a Water Crisis - Immediate actions your PWS must take.

Treatment Options

Treatment options include ion exchange, reverse osmosis, and electrodialysis. Find EPA information about treatment options:

Maximum Contaminant Levels

Public water systems must adhere to requirements for maximum contaminant levels (MCL).

Nitrate and nitrite - Compliance is based on a single sample. TCEQ will notify the PWS if there is an exceedance. PWS must notify customers as soon as possible but no later than 24 hours after determining that a sample exceeds the MCL.

Inorganic contaminants other than nitrate and nitrite - Compliance is determined based on a running annual average of quarterly sampling at each point where treated water enters the distribution system.

If that average exceeds the MCL, the PWS must notify customers as soon as possible but no later than 30 days after the violation is identified.

MCLs for all inorganic contaminants

Public Notice Language for Drinking Water Compliance - Find public notice language and certificate of delivery documents by contaminant for public water systems to use.

Consumer Confidence Report - Community water systems must provide the minimum, maximum, and average levels of any contaminant detected in their annual Consumer Confidence Report, due to their customers by July 1 of each year. A community water system supplies water to the same population year-round.

Monitoring and Sampling

Every public water system (PWS) in Texas must allow for sampling of chemical contaminants. Unlike sampling for lead and copper, water quality parameters, microbial (coliform and E. coli), and disinfectant residuals—TCEQ uses contractors to collect samples for inorganic contaminants which include arsenic, asbestos, fluoride, minerals, metals, nitrate, and nitrite.

All water contains inorganic compounds unless it is distilled. Only chemicals that are known to pose a risk to human health require routine sampling and action if violations occur.

Assistance and Tools for Public Water Systems

Technical Guidance for Public Water System Operators and Engineers
Find information about technical questions, such as submitting plans, exploring treatment options, or requesting exceptions to design or capacity rules.

Texas Drinking Water Watch
Check the information TCEQ has for your PWS including chemical results, bacteriological results, sample schedules, violations, and contact information. This database is free and open to the public.

Courtesy Compliance Reminders for Public Water System Operators
Receive courtesy reminders for important public water system compliance requirements and deadlines by text or email.

Public Water Supply: Compliance Resources
Information, guidance, and forms for PWSs in Texas.

Financial, Managerial and Technical Assistance
TCEQ offers FREE financial, managerial, and technical (FMT) assistance to help public water systems comply with regulations. Contact FMT for help with issues such as, but not limited to preventing operational problems, training about how to comply with rule requirements and performing capacity assessments.