Dallas Water Quality & Filtration Guide

Introduction To Water Quality in Dallas

Dallas Water Utilities (DWU) provides drinking water to approximately 1.28 million residents through an extensive network of treatment facilities and distribution infrastructure. While Dallas has earned the "Superior Public Water System" designation from the Texas Commission on Environmental Quality (TCEQ) and consistently meets all federal and state regulatory requirements, independent testing has identified several contaminants at levels that may raise health concerns with long-term exposure.

Unlike many Texas municipalities that rely on groundwater, Dallas obtains its drinking water exclusively from surface water sources within the Trinity River watershed, including:

• Elm Fork of the Trinity River
• Lake Ray Roberts
• Lake Lewisville
• Lake Grapevine
• Lake Ray Hubbard
• Lake Tawakoni
• Lake Fork

The city plans to supplement these sources with water from Lake Palestine by 2027 to address increased future consumption needs. Water from these sources undergoes a comprehensive treatment process at three water treatment plants: East Side, Elm Fork, and Bachman.

Contaminants and Pollutants in your Local Water

Despite regulatory compliance with federal standards, several concerning contaminants have been detected in Dallas drinking water. These substances remain below legal limits but exceed health guidelines established by independent organizations like the Environmental Working Group (EWG).

The primary contaminants of concern in Dallas water include:

• PFAS ("Forever Chemicals"): Multiple PFAS compounds have been detected, including PFBA, PFBS, PFHpA, PFHxA, PFHxS, PFOA, PFOS, and PFPeA
• Arsenic: Detected at 0.297 ppb (74 times above EWG's Health Guideline but below the federal limit)
• Disinfection Byproducts: Including haloacetic acids (HAA5), dibromoacetic acid, dichloroacetic acid, and total trihalomethanes
• Additional Contaminants: A 2019 EWG study identified 37 total contaminants in Dallas water, with 10 exceeding health guidelines

These contaminants, while meeting legal standards, may pose long-term health risks to Dallas residents, particularly vulnerable populations such as pregnant women, infants, and children.

Explanation of Contaminants and their Problems

PFAS ("Forever Chemicals")

Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic chemicals that have been manufactured since the 1940s and used in various consumer products, firefighting foams, and industrial applications. Their extreme persistence in both the environment and human body has earned them the nickname "forever chemicals."

Recent testing through EPA's Unregulated Contaminant Monitoring Rule has detected eight different PFAS compounds in Dallas water, with some found in 100% of samples:

• PFBA: Found in all samples at 7.7-13.2 ppt
• PFBS: Found in all samples at 3.0-7.6 ppt
• PFHxA: Found in all samples at 4.5-17.9 ppt
• PFPeA: Found in all samples at 4.9-18.2 ppt

Health concerns associated with PFAS exposure include:

• Developmental effects: Decreased birth weight, accelerated puberty, skeletal variations, and immune system development problems in fetuses and children
• Cancer risk: Particularly testicular and kidney cancers (PFOA and PFOS are considered likely carcinogenic)
• Liver damage: Affecting both function and structure
• Immune system suppression: Decreased antibody response to vaccination and suppressed immune function
• Thyroid hormone disruption: Affecting overall metabolic regulation
• Cardiovascular issues: Including cholesterol changes and heart problems

Pregnant women, infants, and developing children face heightened risks from PFAS exposure due to their developing bodies and systems.

Arsenic

Arsenic was detected in Dallas water at 0.297 ppb, which is 74 times above EWG's Health Guideline of 0.004 ppb but well below the federal legal limit of 10 ppb. This naturally occurring element typically enters water supplies through erosion of natural deposits.

Long-term exposure to arsenic, even at low levels, has been linked to serious health problems:

• Thickening and discoloration of the skin
• Gastrointestinal problems including stomach pain, nausea, vomiting, and diarrhea
• Cardiovascular disorders including heart disease and high blood pressure
• Neurological effects including numbness and pain
• Multiple cancers including bladder, lung, skin, kidney, liver, and prostate

Children face increased health risks from arsenic exposure as their developing bodies absorb more arsenic relative to body weight. While Dallas levels are far below the threshold for acute toxicity (130 ppb), the chronic low-level exposure remains a concern for long-term health.

Disinfection Byproducts

Disinfection byproducts form when disinfectants like chlorine react with naturally occurring organic matter in the water. Several have been detected in Dallas water at levels exceeding health guidelines:

• Haloacetic acids (HAA5): Found at 11.4 ppb (114 times above EWG's Health Guideline but below the legal limit of 60 ppb)
• Dibromoacetic acid: Found at 1.03 ppb (26 times above EWG's Health Guideline)
• Dichloroacetic acid: Found at 7.55 ppb (38 times above EWG's Health Guideline)
• Total Trihalomethanes: Present but below legal limits

Long-term health concerns associated with these compounds include:

• Increased cancer risk with extended exposure
• Liver and kidney damage
• Central nervous system impacts, including developmental concerns
• Reproductive effects and potential pregnancy complications

While these byproducts pose long-term health concerns, they must be balanced against the essential public health benefits of disinfection, which prevents immediate and potentially fatal waterborne diseases.

Deep Dive on Surface Water Quality in the Area

Trinity River Watershed Water Quality

Dallas relies exclusively on surface water from the Trinity River watershed, which provides water for nearly half of all Texans. The water in this system faces several challenges:

• Urban runoff: The watershed encompasses heavily developed areas, contributing pollutants from roads, lawns, and industrial areas
• Agricultural impacts: Fertilizers, pesticides, and animal waste from agricultural operations within the watershed
• Seasonal variability: Quality can fluctuate with rainfall patterns and seasonal changes
• Industrial discharge: Historical and current industrial activities affect water quality

The Trinity River has seen significant improvement over recent decades due to enhanced regulations and restoration efforts. However, as a surface water source, it remains inherently more vulnerable to contamination than deep groundwater sources.

Dallas's water treatment system addresses many conventional pollutants through its multi-stage process:

• Chemical treatment
• Coagulation with iron sulfate
• Sedimentation
• Filtration
• Disinfection with chloramine or ozone
• Additional treatments including lime, activated carbon, orthophosphate, and fluoride

While this process effectively addresses pathogens and many conventional pollutants, it has limitations in removing certain contaminants of emerging concern like PFAS.

Filtration Recommendations for Dallas

Based on the identified contaminants in Dallas water, a multi-barrier filtration approach is recommended to provide comprehensive protection:

PFAS Removal

For effective PFAS reduction, three primary technologies have proven effective:

• Activated Carbon Filtration: Particularly effective for longer-chain PFAS like PFOA and PFOS (60-70% removal) but less effective for shorter-chain compounds (approximately 40% removal)
• Ion Exchange Resins: Particularly effective for perfluorosulfonic acids including PFOS
• Reverse Osmosis: Most comprehensive PFAS removal technology, capable of near-complete removal of all PFAS compounds, including shorter-chain varieties

Arsenic Removal

For arsenic reduction, effective technologies include:

• Reverse Osmosis: Highly effective at removing dissolved arsenic
• Activated Aluminum/Carbon Filters: Specialized absorbents effectively capture arsenic ions
• Ion Exchange Resins: Use strong base and ion exchange materials to selectively remove arsenic
• Oxidation Pretreatment: Converting arsenite (As III) to arsenate (As V) significantly improves removal efficiency

Disinfection Byproducts Removal

For haloacetic acids and other disinfection byproducts:

• Activated Carbon Filtration: Most effective method for HAA removal
• Reverse Osmosis Systems: Capable of removing most disinfection byproducts through their semi-permeable membranes

Recommended System Configuration

For Dallas residents, the optimal filtration solution would be a multi-stage system:

1. Primary Treatment: High-quality activated carbon filtration to address disinfection byproducts and longer-chain PFAS compounds
2. Secondary Treatment: Reverse osmosis for comprehensive contaminant reduction of remaining PFAS, arsenic, and other dissolved contaminants
3. Remineralization: After reverse osmosis to restore beneficial minerals to the water

This combined approach would effectively address all identified contaminants of concern while providing water that is both safe and pleasant to consume. Point-of-use systems (under sink or countertop) typically perform better for disinfection byproduct removal than whole-house systems due to the shorter contact time with new disinfectants in household plumbing.

Regular maintenance and periodic water quality testing remain essential components of any water quality management strategy to ensure continued effective operation and protection.

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