Lewisville Water Quality & Filtration Guide

Introduction To Water Quality in Lewisville

Lewisville, Texas maintains a "Superior Public Water Supply" rating from the Texas Commission on Environmental Quality (TCEQ), meeting all federal drinking water standards. This is the highest rating given by the regulatory agency, reflecting the city's commitment to water quality. However, despite this impressive designation, testing reveals several contaminants at levels exceeding health guidelines established by the Environmental Working Group (EWG), though still within legal limits.

The city's water system draws primarily from surface water sources, with Lewisville Lake serving as the main supply. The system is supplemented with treated water purchased from Dallas Water Utility and the Upper Trinity Regional Water District. Together, these sources provide water from six reservoirs and the Elm Fork of the Trinity River: Grapevine, Lewisville, Ray Roberts, Ray Hubbard, Fork, and Tawakoni.

Lewisville's water treatment process involves multiple purification methods:

• Settling to remove larger suspended particles
• Filtration to eliminate finer particulate matter
• Chemical treatment using lime and iron sulfate
• Disinfection with chloramine (chlorine and ammonia) and ozone
• Taste and odor control with activated carbon
• Fluoridation for dental health

While the municipal system doesn't use groundwater, the Trinity Aquifer underlies the region and serves as a source for private wells. This aquifer presents its own set of water quality challenges that differ from the municipal supply.

Contaminants and Pollutants in your Local Water

Although Lewisville's municipal water meets all federal standards, several contaminants have been detected at levels exceeding the more stringent health guidelines established by the Environmental Working Group:

• Arsenic: Found at 0.723 ppb, which is 181 times higher than EWG's health guideline of 0.004 ppb (though still below the legal limit of 10 ppb)
• Chromium (hexavalent): Detected at levels 9.7 times above EWG's health guideline of 0.02 ppb
• Dibromoacetic acid: Present at 0.593 ppb, which is 15 times higher than EWG's health guideline of 0.04 ppb (no federal legal limit established)
• Total trihalomethanes (TTHMs): Measured at 16.9 ppb, 113 times higher than EWG's health guideline of 0.15 ppb (legal limit is 80 ppb)
• Trichloroacetic acid: Found at 3.12 ppb, which is 31 times higher than EWG's health guideline of 0.1 ppb

Additional contaminants detected in Lewisville's water, though at levels below health guidelines, include:

• Chlorate: 68.2 ppb (below EWG guideline of 210 ppb)
• Chromium (total): 0.593 ppb (legal limit: 100 ppb)
• Various other disinfection byproducts including bromochloroacetic acid, bromodichloromethane, chloroform, dibromochloromethane, and dichloroacetic acid

Explanation of Contaminants and their Problems

Arsenic

Arsenic is a potent carcinogen commonly found in drinking water that poses serious health risks even at low exposure levels. Long-term consumption of water containing arsenic can lead to:

• Cancer development: Increased risk of cancers affecting the bladder, lungs, liver, kidney, prostate, and other organs
• Metabolic disruption: Associated with the development of diabetes
• Cardiovascular damage: Contributes to heart disease and respiratory conditions
• Neurological impairment: Can cause reduced intelligence in children and nerve damage resulting in numbness and/or pain
• Skin problems: May cause thickening and discoloration of the skin, lesions, and corns

Certain populations face heightened risks from arsenic exposure, particularly young children, the elderly, and unborn babies. For infants especially, water with arsenic levels above 35 ppb should not be consumed even for short periods due to developmental risks.

Trihalomethanes (TTHMs)

Trihalomethanes are cancer-causing contaminants formed during water treatment when chlorine and other disinfectants react with naturally occurring organic matter. The TTHMs group includes four chemicals: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.

Prolonged exposure to TTHMs can cause:

• Liver damage: People drinking water with elevated TTHMs over many years may experience liver problems
• Kidney deterioration: Extended exposure can lead to kidney damage
• Neurological effects: Potential impacts on the central nervous system
• Increased cancer risk: Long-term exposure raises cancer probability

While TTHMs pose health concerns, it's important to note that the risk of not disinfecting drinking water—and potentially exposing people to dangerous microorganisms—outweighs the long-term, low-level risk of disinfection byproducts at levels typically found in U.S. water supplies.

Haloacetic Acids

Haloacetic acids, including dibromoacetic acid and trichloroacetic acid found in Lewisville's water, are another group of disinfection byproducts. They form when chlorine or other disinfectants react with naturally occurring organic matter in water.

Health concerns associated with haloacetic acids include:

• Increased cancer risk with long-term exposure
• Potential reproductive health problems, particularly during pregnancy

Chromium (Hexavalent)

Hexavalent chromium (chromium-6) is a form of the metallic element chromium that can occur naturally in minerals but is also produced by industrial processes. While it's recognized primarily as a carcinogen when inhaled, growing evidence suggests it may also be carcinogenic when ingested through drinking water.

Health effects associated with hexavalent chromium exposure include:

• Cancer risk: Particularly lung cancer when inhaled, with evidence suggesting digestive system cancers when ingested
• Organ damage: Can cause liver and kidney damage with prolonged exposure
• Reproductive harm: Potential impacts on reproductive health

Deep Dive on Well Water Quality in the Area

Trinity Aquifer Water Quality

The Trinity Aquifer is a major groundwater system extending across much of central and northeastern Texas, including the Lewisville area. It consists of several smaller aquifers contained within the Trinity Group: Antlers, Glen Rose, Paluxy, Twin Mountains, Travis Peak, Hensell, and Hosston aquifers.

Water quality in the Trinity Aquifer varies significantly by location and depth, presenting unique challenges for private well owners in Lewisville. In general, the water is fresh but very hard in the outcrop areas. As depth increases, water quality tends to deteriorate with higher levels of dissolved minerals and salts.

Key water quality parameters for the Trinity Aquifer in the north-central Texas region show concerning levels of several substances:

• Total Dissolved Solids (TDS): Average of 718 mg/L, with samples ranging from 221 mg/L to over 2,038 mg/L (exceeding the secondary maximum contaminant level of 500 mg/L)
• Chloride: Average of 98.21 mg/L, with some samples reaching up to 647 mg/L
• Sodium: Average of 245.26 mg/L, with concentrations as high as 657 mg/L
• Nitrate (as N): Average of 1.00 mg/L, with some samples exceeding 18.50 mg/L
• Sulfate: Average of 103.10 mg/L, with concentrations up to 725 mg/L
• Fluoride: Average of 0.90 mg/L, with levels up to 3.06 mg/L

The areas showing the highest TDS concentrations include north-central Tarrant County and parts of Denton County, where Lewisville is located. This means private well owners in Lewisville are likely to face significant water quality challenges requiring specialized filtration solutions.

Additional concerns for private well owners include:

• Heavy Metals: The U.S. Geological Survey has found multiple contaminants in Trinity Aquifer samples, including antimony, beryllium, cadmium, cobalt, and silver.
• Pesticides: Detections of atrazine, deethyl atrazine, and pp'-DDE have been found in Trinity Aquifer samples.
• Emerging Contaminants: Recent studies have identified PFAS "forever chemicals" in the region's water systems, potentially affecting groundwater resources as well.
• Declining Water Levels: Some of the state's largest water level declines, ranging from 350 to more than 1,000 feet, have occurred in this region, which can concentrate contaminants and affect water quality.

Filtration Recommendations for Lewisville

Based on the contaminants identified in both Lewisville's municipal water system and the Trinity Aquifer serving private wells, we recommend tailored filtration approaches to ensure safe, clean drinking water.

Municipal Water Filtration Solutions

For homeowners connected to Lewisville's municipal water system, we recommend:

Basic Protection: Activated Carbon Filtration

• Highly effective for removing or reducing:
  • Total trihalomethanes (TTHMs)
  • Haloacetic acids (including dibromoacetic acid and trichloroacetic acid)
  • Chlorine and chloramine
  • Many volatile organic compounds (VOCs)
• Available in various formats including pitcher filters, faucet-mounted systems, and under-sink units

Comprehensive Protection: Reverse Osmosis (RO) Systems

• Provides superior filtration for:
  • Arsenic (up to 99% removal)
  • Chromium (hexavalent)
  • TTHMs and haloacetic acids
  • Total dissolved solids
  • Heavy metals and many other contaminants
• Typically installed as under-sink systems with a dedicated drinking water faucet
• Offers the most complete solution for addressing all identified contaminants of concern

Specialized Treatment: Ion Exchange Systems

• Particularly effective for:
  • Arsenic removal
  • Chromium (hexavalent) reduction
  • Hard water minerals
• Often used as a complementary technology alongside other filtration methods

Well Water Filtration Solutions

For private well owners drawing from the Trinity Aquifer, more comprehensive treatment approaches are necessary:

Multi-Stage Filtration Systems

• Sequential treatment stages to address the complex mix of contaminants:
  • Sediment pre-filtration to remove particles and protect subsequent filtration stages
  • Activated carbon for chemical contaminants, taste, and odor
  • Specialized media for specific contaminants like arsenic or fluoride
  • Final polishing filtration

Specialized Well Water Treatment for High TDS

• Reverse osmosis systems capable of handling elevated TDS levels (up to 5000 ppm)
• Systems that include pre-treatment for sediment and chemical contaminants to protect the RO membrane
• Consideration of whole-house RO for comprehensive protection

Whole House vs. Point-of-Use Considerations

• Whole house systems treat all water entering the home, protecting plumbing and appliances
• Point-of-use systems (like under-sink RO) provide highest-quality water for drinking and cooking
• For Trinity Aquifer water with high TDS, a combination approach may be optimal

Addressing Specific Contaminants of Concern

Arsenic Removal

• Reverse osmosis (preferred method, up to 99% removal)
• Ion exchange with special arsenic-selective resins
• Activated alumina adsorption media

Trihalomethanes and Haloacetic Acids Reduction

• Activated carbon filtration (primary method)
• Reverse osmosis as a comprehensive solution

Hexavalent Chromium Reduction

• Reverse osmosis systems
• Ion exchange with specialized chromium-selective resins
• Reduction filtration (converts hexavalent chromium to less harmful trivalent form)

High TDS Water Treatment

• Reverse osmosis (removes up to 99% of dissolved solids)
• Nanofiltration for selective removal of specific dissolved solids
• Water softening for hardness minerals

For most Lewisville residents, we recommend at minimum an activated carbon filtration system to address disinfection byproducts like trihalomethanes and haloacetic acids. For comprehensive protection against all identified contaminants, including arsenic and hexavalent chromium, a reverse osmosis system provides the most complete solution.

Private well owners should consider multi-stage filtration systems addressing the complex range of potential contaminants in Trinity Aquifer water, with particular attention to high TDS levels that can damage plumbing and appliances.

Regardless of water source, regular maintenance of filtration systems according to manufacturer guidelines and periodic water testing are essential to ensure ongoing protection against the contaminants present in Lewisville's water supply.

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