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Health Indicator Report of Drinking Water: Disinfection Byproducts (DBPs)

People drink and use water every day. The majority of Americans are provided with high quality drinking water. About 90% of people in the U.S. (262 million in 2006) get their water from a community water system (CWS) versus a smaller water supply such as a household well. The U.S. Environmental Protection Agency (EPA) sets regulations for treating and monitoring drinking water delivered by CWS. Currently, there are water quality standards and monitoring requirements for over 90 contaminants. Drinking water protection programs play a critical role in ensuring high quality drinking water and protecting the public's health.

Because people drink and use water every day, contaminants in drinking water have the potential to affect many people. The number of people served by a CWS varies from at least 25 people to hundreds of thousands. CWS in the U.S. provide among the highest quality drinking water in the world. However, some contaminants are present at low levels, and it is still possible that drinking water can become contaminated at higher levels. If a person is exposed to a high enough level of a contaminant, they may become ill. Effects can be seen by the duration (time) of the exposure. Short-term or long-term effects depend on the specific contaminant, the level of contaminant in the water, and the person's individual susceptibility. As additional information is obtained about how specific contaminants affect public health, standards may change in order to better protect public health.

In order to ensure the public's safety with regards to drinking water, community water suppliers treat their water with several products including: chlorine, ozone, chlorine dioxide, ultraviolet light, etc. These products that are used to kill pathogens, however, sometimes react with naturally-occurring organic matter, and create disinfection byproducts (DBPs). DBPs for which the EPA has created standards include: total trihalomethanes (TTHM), haloacetic acids (HAA5), bromate, and chlorite. Although the risk of illness from drinking water that has not been disinfected is much higher than illness from DBPs, some increased health risks do occur from consumption of DBPs. Consumption (through inhalation, ingestion, and absorption through the skin) at high levels over a long period of time has been shown to increase the risk of developing bladder cancer. Rectal and colon cancer along with problems involving the liver, kidney, and nervous system have also been shown to have a correlation with those who have been exposed to DBPs over a long period of time.

DBPs are formed when disinfectants are used to inactivate microbial contaminants in water and react with materials, primarily organic matter, in the water. Several hundred DBPs in over a dozen chemical classes have been identified. (Modified from the National Environmental Public Health Tracking Network (NEPHTN) Nationally Consistent Data and Measures (NCDM) DBP indicator document, version 4).

DPB levels tend to be highest in water derived from surface sources because ground water generally has little organic matter. Ground water can, however, produce relatively high levels of the more brominated DBPs when the water, due to either geological circumstances or salt water intrusion in coastal areas, has elevated levels of bromide. (Modified from the NEPHTN NCDM DBP indicator document, version 4).
Year and Quarter2009 Q32009 Q42010 Q12010 Q22010 Q32010 Q42011 Q12011 Q22011 Q32011 Q42012 Q12012 Q22012 Q32012 Q42013 Q12013 Q22013 Q32013 Q42014 Q12014 Q22014 Q32014 Q42015 Q12015 Q22015 Q32015 Q42016 Q12016 Q22016 Q32016 Q42017 Q12017 Q22017 Q32017 Q42018 Q12018 Q22018 Q32018 Q42019 Q12019 Q22019 Q32019 Q40.050.0100.0150.0200.0250.0300.0350.0Number of CWSQuarterly Distribution of Number of Community Water Systems (CWS) by Mean THM(trihalomethanes) Concentration, Utah, 2010-2019<=80>80Not Detected
 THM Concentration (ug/L)Year and QuarterNumber of CWS

<=80

 0<=802009 Q3
 0<=802009 Q4
 0<=802010 Q125
 0<=802010 Q222
 0<=802010 Q3118
 0<=802010 Q425
 0<=802011 Q121
 0<=802011 Q217
 0<=802011 Q3111
 0<=802011 Q422
 0<=802012 Q127
 0<=802012 Q231
 0<=802012 Q398
 0<=802012 Q457
 0<=802013 Q158
 0<=802013 Q265
 0<=802013 Q3159
 0<=802013 Q467
 0<=802014 Q166
 0<=802014 Q256
 0<=802014 Q3183
 0<=802014 Q453
 0<=802015 Q160
 0<=802015 Q255
 0<=802015 Q3155
 0<=802015 Q463
 0<=802016 Q160
 0<=802016 Q263
 0<=802016 Q3211
 0<=802016 Q478
 0<=802017 Q171
 0<=802017 Q277
 0<=802017 Q3202
 0<=802017 Q483
 0<=802018 Q186
 0<=802018 Q281
 0<=802018 Q3196
 0<=802018 Q480
 0<=802019 Q174
 0<=802019 Q278
 0<=802019 Q3218
 0<=802019 Q487

>80

 5>802009 Q3
 5>802009 Q4
 5>802010 Q10
 5>802010 Q20
 5>802010 Q32
 5>802010 Q40
 5>802011 Q10
 5>802011 Q20
 5>802011 Q30
 5>802011 Q40
 5>802012 Q10
 5>802012 Q20
 5>802012 Q31
 5>802012 Q40
 5>802013 Q10
 5>802013 Q20
 5>802013 Q31
 5>802013 Q41
 5>802014 Q10
 5>802014 Q20
 5>802014 Q33
 5>802014 Q40
 5>802015 Q10
 5>802015 Q21
 5>802015 Q33
 5>802015 Q42
 5>802016 Q10
 5>802016 Q22
 5>802016 Q32
 5>802016 Q41
 5>802017 Q10
 5>802017 Q22
 5>802017 Q37
 5>802017 Q43
 5>802018 Q10
 5>802018 Q20
 5>802018 Q32
 5>802018 Q41
 5>802019 Q11
 5>802019 Q22
 5>802019 Q38
 5>802019 Q42

Not Detected

 7Not Detected2009 Q3
 7Not Detected2009 Q4
 7Not Detected2010 Q16
 7Not Detected2010 Q23
 7Not Detected2010 Q327
 7Not Detected2010 Q44
 7Not Detected2011 Q13
 7Not Detected2011 Q25
 7Not Detected2011 Q326
 7Not Detected2011 Q41
 7Not Detected2012 Q11
 7Not Detected2012 Q25
 7Not Detected2012 Q321
 7Not Detected2012 Q42
 7Not Detected2013 Q10
 7Not Detected2013 Q21
 7Not Detected2013 Q325
 7Not Detected2013 Q44
 7Not Detected2014 Q10
 7Not Detected2014 Q20
 7Not Detected2014 Q331
 7Not Detected2014 Q44
 7Not Detected2015 Q11
 7Not Detected2015 Q21
 7Not Detected2015 Q338
 7Not Detected2015 Q45
 7Not Detected2016 Q14
 7Not Detected2016 Q22
 7Not Detected2016 Q344
 7Not Detected2016 Q46
 7Not Detected2017 Q14
 7Not Detected2017 Q21
 7Not Detected2017 Q343
 7Not Detected2017 Q43
 7Not Detected2018 Q11
 7Not Detected2018 Q22
 7Not Detected2018 Q347
 7Not Detected2018 Q48
 7Not Detected2019 Q110
 7Not Detected2019 Q23
 7Not Detected2019 Q365
 7Not Detected2019 Q49

Data Source

Utah Department of Environmental Quality, Division of Drinking Water, Safe Drinking Water Information System (SDWIS)

Data Interpretation Issues

A community water system (CWS) is a public water system that serves at least 15 service connections used by year-round residents or regularly serves at least 25 year-round residents. The current measures are derived for CWS only. Transient non-community water systems, which are regulated by the Environmental Protection Agency (EPA), may also be an important source of disinfection byproducts (DBP) exposure. Measures do not account for the variability in sampling, numbers of sampling repeats, and variability within systems. Concentrations in drinking water cannot be directly converted to exposure because water consumption varies by climate, level of physical activity, and between people (EPA 2004). Due to errors in estimating populations, the measures may overestimate or underestimate the number of affected people. (Modified from the National Environmental Public Health Tracking Network [NEPHTN] Nationally Consistent Data and Measures [NCDM] DBP indicator document, version 4)

The Safe Drinking Water Act compliance data include only a handful of the hundreds of known disinfection byproducts, most of which occur in chemical classes other than trihalomethanes (THM) and haoacetic acids (HAA) (Weinberg et al. 2002). While compliance sampling for THMs and HAAs are directed at the DBPs thought to be the most commonly produced by chlorination, non-regulated DBP exist even among the THMs and HAAs. (Modified from the NEPHTN NCDM DBP indicator document, version 4)

Concern has also been expressed about iodinated THMs and HAAs which, while present in lower concentrations than the brominated and chlorinated THMs, are thought to be toxic at lower doses (e.g. Plewa et al. 2004). THMs and HAAs may not be the most comprehensive indicators of DBP levels in water, because alternative disinfection methods produce different DBPs and may result in high levels of these unregulated DBPs. Little is known about the quantitative occurrence of these DBPs in the distribution system (Richardson et al. 2002, Krasner et al. 2006). While the health effects of different DBPs may vary, with some suspected to be hazardous, few have been characterized for their effects on human health (Woo et al. 2002). (Modified from the NEPHTN NCDM DBP indicator document, version 4)

DBP levels vary seasonally. Quarterly samples may not capture maximum levels and may not even adequately reflect short term levels. Therefore, they may be inadequate for estimating exposure during critical periods of a pregnancy which may be as short as two to three weeks, especially if peak exposure matters more than average exposure. Furthermore, these fluctuations make it difficult to characterize levels with a single number, such as an annual average, and thus pose challenges to the development of meaningful synopses of patterns and trends. (Modified from the NEPHTN NCDM DBP indicator document, version 4)

Definition

Mean Trihalomethane Levels for Utah
1) Yearly distribution of number of community water systems (CWS) by mean trihalomethane (THM) concentration
2) Yearly distribution of number of people served by CWS by mean THM concentration

Maximum Trihalomethane Levels for Utah
3) Yearly distribution of number of CWS by maximum THM concentration
4) Yearly distribution of number of people served by CWS by maximum THM concentration

Mean Trihalomethane Levels for Utah by Quarter
5) Quarterly distribution of number of CWS by mean THM concentration
6) Quarterly distribution of number of people served by CWS by mean THM concentration

Mean Haloacetic Acid Levels for Utah
7) Yearly distribution of number of CWS by mean haloacetic acid (HAA5) concentration
8) Yearly distribution of number of people served by CWS by mean HAA5 concentration

Maximum Haloacetic Acid Levels for Utah
9) Yearly distribution of number of CWS by maximum HAA5 concentration
10) Yearly distribution of number of people served by CWS by maximum HAA5 concentration

Mean Haloacetic Acid Levels for Utah by Quarter
11) Quarterly distribution of number of CWS by mean HAA5 concentration
12) Quarterly distribution of number of people served by CWS by mean HAA5 concentration

Numerator

Counts of community water systems (CWS) by year, number of people served by a CWS by year, counts of CWS per quarter, and number of people served by a CWS per quarter.

Denominator

Not applicable.

Page Content Updated On 05/10/2021, Published on 05/20/2021
The information provided above is from the Utah Department of Health and Human Services IBIS-PH web site (https://ibis.utah.gov/epht-view/). The information published on this website may be reproduced without permission. Please use the following citation: " Retrieved Fri, 28 March 2025 7:23:49 from Utah Department of Health and Human Services, Indicator-Based Information System for Public Health Web site: https://ibis.utah.gov/epht-view/ ".

Content updated: Thu, 6 Feb 2025 13:01:20 MST