Water Quality Report 2017

The Winston-Salem/Forsyth County Utility Commission operates three water treatment facilities drawing water from both the Yadkin River and Salem Lake. Together, these water treatment facilities can produce 91 million gallons per day of drinking water. The Neilson and Swann water plants can treat 48 and 25 million gallons per day, respectively, from the Yadkin River. The Thomas Water Plant treats 18 million gallons per day from Salem Lake and the Yadkin River.

For 2017, as in previous years, these treatment facilities have met or exceeded all state and federal standards for drinking water quality. This accomplishment reflects the quality and dedication of the employees who work year-round to provide adequate supplies of safe drinking water.

This report includes details about where your drinking water comes from, how it is treated, what it contains, and exactly how it compares to state and federal standards. The Utility Commission is providing this information to you because it is committed to delivering a quality product to its customers. This report is updated on a regular basis and made available annually to our customers.

Protecting Our Water Sources

Sources of drinking water (both tap and bottled) include rivers, lakes, 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, and can pick up substances resulting from the presence of animals or from human activity.

Contaminants that may be present in source water include:

  • Microbial contaminants such as viruses and bacteria, which may come from sewage treatment plants, septic systems, agricultural livestock opera- tions, and wildlife.
  • Inorganic contaminants such as salts and metals which can be naturally-occurring or result from urban storm water runoff, industrial or wastewater discharges, oil and gas productions, mining or farming.
  • Pesticides and herbicides, which may come from a variety of sources such as agriculture, urban storm water runoff, and residential uses.
  • Organic chemical contaminants, including synthetic and volatile organic chemicals, which are by-products of industrial processes and petroleum production, and can come from gas stations, urban storm water runoff, and septic systems.
  • Radioactive contaminants which can be naturally occurring or the result of oil and gas production and mining activities.

To ensure that tap water is safe to drink, the Environmental Protection Agency (EPA) limits the amount of certain contaminants in water provided by public water systems. Food and Drug Administration regulations establish limits for contaminants in bottled water, which must provide the same protection for public health.

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 the water poses a health risk. More information about contaminants and potential health effects can be obtained by calling the EPA's Safe Drinking Water Hotline at 800-426-4791.

Lead Exposure From Water

Elevated levels of lead in drinking water can cause serious health problems, especially for pregnant women and young children. Lead in drinking water comes primarily from materials and components associated with service lines and home plumbing.

The City/County Utility Commission is responsible for providing high quality drinking water, but cannot control the variety of materials used in plumbing components. When your water has been sitting for several hours, you can minimize the potential for lead exposure by flushing your tap for 30 seconds to two minutes before using water for drinking or cooking.

If you are concerned about lead in your water, you may wish to have your water tested. Information and steps you can take to minimize exposure is available from the Safe Drinking Water Hotline at 800-426-4791 or go online at the United States Environmental Protection Agency.

Treated Quarter Quality Chart 2017

Treated Quarter Quality Chart 2017 (JPG) Opens in new window


  1. Maximum Contaminant Level (MCL) - The highest level of a contaminant that is allowed in drinking water.
  2. Maximum Contaminant Level Goal (MCLG) - The level of a contaminant in drinking water below which there is no known or expected risk to health.
  3. One part per billion (Ppb) - (For example, one penny in $10,000,000.)
  4. One part per million (Ppm) - (For example, one penny in $10,000.)
  5. The EPA's maximum contaminant level for fluoride is 4.0 Milligrams per Liter (mg/L), however the State of North Carolina has established a maximum contaminant level of 2.0 mg/L.
  6. Treatment technique - Treatment technique for total organic carbon was complied with throughout 2016.
  7. Nephelometric Turbidity Unit (NTU) - a measure of the cloudiness of water.
  8. Treatment technique - 95% of the measurements taken in one month must be below 0.3 NTU.
  9. Locational running annual average - average of last four quarters of samples collected at each location at 12 monitoring sites.
  10. Millions of Fibers Per Liter (MFL) - A measure of asbestos contamination as measured by millions of fibers per liter of water
  11. Picocuries Per Liter (PCi/L) - Picocuries per liter is a measure of the radioactivity in water. A picocurie is 10 to 12 curies and is the quantity of radioactive material producing 2.22 nuclear transformations per minute.
  12. April 1 TC positive out of 185 equals 0.54%, August 2 TC positives out of 183 equals 1.09%
  13. Action Level - The concentration of a contaminant that triggers treatment or other requirement that a water system must follow. Action levels are reported at the 90th percentile for homes at greatest risk.

Physical & Mineral Characteristics - 2017 Calendar Year

Physical and Mineral Characteristics - 2017 Calendar Year (JPG) Opens in new window

Cryptosporidium sp. - is a microscopic organism that, when ingested, can cause diarrhea, fever and other gastrointestinal symptoms. The organism occurs naturally in surface waters (lakes and streams) and comes from animal waste. Cryptosporidium sp. is eliminated by an effective treatment combination of coagulation, sedimentation, filtration, and disinfection.

Both of the city's water sources are currently being tested monthly for Cryptosporidium sp. and to date it has not been detected. Cryptosporidium sp. has never been detected in our treated drinking water.

Special Concerns - Some people may be more vulnerable to contaminants in drinking water than the general population. People whose immune systems have been compromised - such as people with cancer undergoing chemotherapy, persons who have undergone organ transplants, people with HIV/AIDS or other immune system disorders, some elderly, and infants - can be particularly at risk for infections. These people should seek advice about drinking water from their health care providers. Environmental Protection Agency and Centers for Disease Control guidelines on appropriate means to lessen risk of infection by Cryptosporidium sp. and other microbiological contaminants are available from the Safe Drinking Water Hotline at 800-426-4791.

En Español - Si desea recibir una copia de este reporte en Español o si tiene preguntas con respecto a la calidad del agua que consume, por favor comuniquese con el departamento the servicios públicos durante las horas de trabajo, el teléfono es 336-727-8000.

North Carolina Drinking Water Assessment

The North Carolina Department of Environmental Quality (DEQ), Public Water Supply (PWS) Section, Source Water Assessment Program (SWAP) conducted assessments for all drinking water sources across North Carolina. The purpose of the assessments was to determine the susceptibility of each drinking water source (well or surface water intake) to Potential Contaminant Sources (PCSs). The results of the assessment are available in SWAP Assessment Reports that include maps, background information and a relative susceptibility rating of Higher, Moderate or Lower.

The relative susceptibility rating of each source for the City of Winston-Salem (PWSID 0234010) was determined by combining the contaminant rating (number and location of PCSs within the assessment area) and the inherent vulnerability rating (i.e, characteristics or existing conditions of the well or watershed and its delineated assessment area). The assessment findings are summarized in the following table:

Source Name
Inherent Vulnerability RatingContaminant RatingSusceptibility Rating
Salem Lake
Yadkin River (Idols Dam)
Yadkin River (PWSWANN WTP)

The complete SWAP Assessment report for the City of Winston-Salem may be viewed on the Web at North Carolina Environmental Quality Please indicate your system name (Winston-Salem, City of) and number (0234010).

Note that because SWAP results and reports are periodically updated by the PWS Section, the results available on this website may differ from the results that were available at the time this CCR was prepared.

If you are unable to access your SWAP report on the web, you may mail a written request for a printed copy to:
Source Water Assessment Program - Report Request
1634 Mail Service Center
Raleigh, NC 27699-1634

You may also email requests. Please indicate your system name (Winston-Salem, City of), number (0234010), and provide your name, mailing address and phone number.

If you have any questions about the SWAP report, please contact the Source Water Assessment staff by phone at 919-707-9098.

It is important to understand that a susceptibility rating of "higher" does not imply poor water quality, only the system's potential to become contaminated by PCSs in the assessment area.

City of Winston-Salem's Lead & Copper Program

The City of Winston-Salem's Lead and Copper Program began in the early 1990s with the implementation of the Lead and Copper Rule (LCR) that was published in the Federal Register by the Environmental Protection Agency (EPA) on June 7, 1991. The recent crisis in Flint, Michigan, has brought the LCR back into the forefront with the public and our industry and has initiated broader discussions centered on what failures occurred, how to prevent them in the future and what changes are necessary to better protect public health. The EPA is currently drafting revisions to the LCR that are expected to be released in 2018. Currently, it is not clear what the exact changes will be but it is anticipated they will be significant, based on the information EPA has published to date.

The LCR is known as a "treatment technique rule" since additional treatment is required, as well as establishing performance-based reduction goals for lead and copper (90th percentile requirement). As a result of early compliance testing required by the rule in the 1990s the Utilities Division installed corrosion control treatment through the use of zinc orthophosphate and caustic soda. Zinc orthophosphate forms a protect layer on the interior of pipes in the distribution system and home plumbing to prevent metals from leaching into the water. Caustic soda supplements the use of zinc orthophosphate by raising the pH into the optimum range for zinc orthophosphate as well as reducing the aggressiveness of water associated with lower pH values. During the 2017 fiscal year our facilities have spent approximately $260,380 on these two chemicals alone to ensure we remain in compliance with the rule.

The rule also requires routine sampling to demonstrate the effectiveness of our corrosion control program. Our system is currently on a reduced triennial (every 3 years) monitoring schedule under which we collect 50 samples from single-family homes built from 1983 to 1985. Our system completed our most recent round of this sampling in 2016 between June 1 and September 30. In order for us to remain in compliance with the rule, 90% of these samples must be below the action level of lead and copper, which is 15.0 ppb and 1,300 ppb, respectively. Since 1992 our system has never exceeded the action level for lead or copper. In addition to the required compliance sampling performed during the 2016 compliance year, our water quality staff have collected and tested additional structures that meet the LCR criteria during the 2017 calendar year, the locations of which are represented on the system map below with red dots; compliance sampling pool locations are indicated by the blue squares. None of the additional samples tested in 2017 exceeded the action levels for lead or copper, which demonstrates our Lead and Copper Treatment Program to be effective.

Water Sampling Sites Lead and Copper Testing Map (JPG) Opens in new window