GLOBAL TASTE AND ODOR SURVEY OF WATER UTILITIES FINAL REPORT. The American Water Works Association Taste and Odor Committee

Transcription

1 GLOBAL TASTE AND ODOR SURVEY OF WATER UTILITIES FINAL REPORT The American Water Works Association Taste and Odor Committee Report prepared by: Pinar Omur-Ozbek, Ph.D. Colorado State University Survey and report overseen by the subcommittee: Stephen Booth, Ph.D., P.E. Confluence Engineering Group, LLC Steven Butterworth, Calgon Carbon Corporation Nathaniel Dunahee, P.E., Burns and McDonnell Monique Durand, P.E., Hazen and Sawyer Thomas Gillogly, Ph.D., Carollo Engineers October 12, 2012 Copyright 2012 American Water Works Association. All Rights Reserved.

2 INTRODUCTION The AWWA Taste and Odor Committee conducted a survey of drinking water utilities, funded by the AWWA s Technical and Educational Council, during September 2011 to May 2012, as an update of the previous survey conducted in 1989 by the AWWA Taste-and-Odor Committee. The goal of the survey was to obtain information on the occurrence of taste-and-odor (T&O) episodes and how the drinking water utilities handled them and the customer complaints. An online survey provided by Qualtrics was utilized for this project and the survey (questionnaire is provided at the end) was ed to 982 drinking water utilities (723 in the US, 195 in Canada, 40 in South Korea, 17 in Australia, 3 in France, and 4 in Turkey) in early September. The contact person from each utility received the questionnaire (as a PDF document) with a separate as well. Periodic reminders were sent to participants and 45% of them were called by phone to encourage participation. At the end of the project period (May 15, 2012), 478 utilities had started the survey however only 381 responses were usable, 168 of which indicated they have T&O issues. Participants indicated that they have either 1) changed source waters over the years, 2) updated the treatment plants for other reasons, 3) did not keep the data from 10 to 20 years before, and 4) they were not employed there for a long time and hence couldn t provide reliable data that dated back more than 5 to 10 years. This should be taken into consideration while evaluating the results. The summary of the data collected by this project is provided in a tabulated or graphed format below. Copyright 2012 American Water Works Association. All Rights Reserved. Page 1

3 SUMMARY OF THE DATA COLLECTED The survey links were specific to each participant to be able to track the source of the data as well as to prevent multiple entries. The data was analyzed and went through a QA/QC process to ensure inclusion of reliable data as well as the correction of units (e.g. MGD, days, costs, etc.) for the related data. The responses obtained from the utilities were pooled and summarized for each question and presented below. 1. Countries surveyed The data for the participating utilities indicated that 86% of the responses came from the US, as 74% of our list included utilities from the USA. There were some contributions from the Canadian and Australian utilities. # of respondents USA Canada Australia South Korea France 2. Number of consumers served by the facility About 3 of the utilities that responded to the survey serve less than 20,000 consumers and another 3 serve 100,000 to 500,000 customers. The majority of the utilities serve small or mid-size towns. # of Consumers % < 20,000 29% 20,001-50,000 13% 50, ,000 18% 100, ,000 29% > 500,000 1 Copyright 2012 American Water Works Association. All Rights Reserved. Page 2

4 3. Total annual budget in US $ The total annual budgets of the utilities followed a similar trend to the number of consumers served. A small portion of the utilities have a less than $1 million or more than $50 million budget. 3 of the utilities have a $1 to $5 million budget and another 3 have a $10 to $50 million budget. Annual Utility Budgets 8% 7% 8% $ < 1 million $ 1-5 million 3 $ 5-10 million $ million 3 $ million $ > 100 million 17% 4. Capacity of the facility The majority of the utilities treat less than 50 MGD of water during average conditions. Under peak demand conditions the number of utilities that serve more than 50 MGD increases about 1. Amount of water treated per day during average demand 9% 14% 42% <10 MGD 10 to 50 MGD 50 to 100 MGD 35% > 100 MGD Copyright 2012 American Water Works Association. All Rights Reserved. Page 3

5 Amount of water treated per day during peak demand 11% 22% 33% <10 MGD 10 to 50 MGD 50 to 100 MGD 34% > 100 MGD 5. Permitted water withdrawal Water withdrawals and the source waters varied among the utilities with different capacities. The main supply of source water was groundwater, closely followed by lake and river. It should be noted that some of the utilities use more than one type of source water. For utilities less than 5 MGD capacity, groundwater was the main source followed by lake. For utilities more than 50 MGD capacity, river followed by lake were more common sources. For high capacity utilities all sources were used equally to meet the demand. Most of the utilities that responded other as source indicated that they buy water from other utilities and a few indicated sources as desalinated brackish water, canals, and desalinated water. Copyright 2012 American Water Works Association. All Rights Reserved. Page 4

6 Types of source water 28% 8% 25% Lake Reservoir River 13% Groundwater Other 26% Permitted water withdrawal based on source water type # of responses <5 MGD 5-50 MGD MGD MGD > 500 MGD Lake Resevoir River Groundwater Copyright 2012 American Water Works Association. All Rights Reserved. Page 5

7 6. Treatment processes The majority (65%) of the utilities that responded used a conventional treatment and about half of those utilities supplement it with activated carbon or advanced treatment practices. Utilities use ozone and UV for disinfection as well as removal of resistant organic compounds. Ultrafiltration and biofiltration are among the other supplemental processes. About a third of the utilities (35%) indicated that they do not employ conventional treatment processes and send the water directly to their consumers after one of the following treatment methods: Chlorination only Ion exchange Iron removal Activated carbon filtration Direct filtration Packed tower aeration Membrane treatment Treatment processes used Conventional 35% 35% Conventional + occasional activated carbon treatment Conventional + advanced treatment, please specify 16% 14% Other, please explain Copyright 2012 American Water Works Association. All Rights Reserved. Page 6

8 7. Disinfectants Chlorine was determined as the most common disinfectant (64%) and is mainly used as the primary choice. Chloramines (19%) and ozone (9%) follow chlorine as the primary choices. The most common secondary disinfectant is chloramines (43%), followed by chlorine. Other disinfectants used by the 2% of the utilities are potassium permanganate and sodium hypochlorite. Disinfectants used % of responses % 45% 43% 31% 19% 15% 9% 9% 1 1 8% 2% 4% 9% 2% Primary choice Secondary choice Occasionally used 8. Distribution system As the sizes of the utilities varied, their distribution systems varied significantly. The information on the distribution system is summarized below. The utilities indicated that they replace the pipes as needed, replace certain lengths (30-40 mi) every year, or replace mains every 5 years. The responses varied based on the budget and length of the distribution system. Length of DS Pipes Age of system Top Pipe Materials Other Pipe Materials Avg Water Age Min 1 mi 0 years Ductile Iron PVC 0.25 days 1 day Max Water Age Avg 810 mi 55 years Cast Iron Steel 2.7 days 10 days Max 13,041 mi 150 years Steel Cement 3 weeks 40 weeks Copyright 2012 American Water Works Association. All Rights Reserved. Page 7

9 9. Water quality The water quality data for source water (SW) and treated water (TW) is summarized below. As expected the water quality varied significantly. Parameter Min Max Avg TOC (mg/l) SW TOC (mg/l) TW DOC (mg/l) SW DOC (mg/l) TW TP (mg/l) SW TP (mg/l) TW TN (mg/l) SW TN (mg/l) TW NH3 (mg/l-n) SW NH3 (mg/l-n) TW H2S (mg/l) SW H2S (mg/l) TW Fe (mg/l) SW Fe (mg/l) TW Mn (mg/l) SW Mn (mg/l) TW ph SW ph TW DO (mg/l) SW DO (mg/l) TW Conductivity (us/cm) SW Conductivity (us/cm) TW Turbidity (NTU) SW Turbidity (NTU) TW Temperature (C) SW Temperature (C) TW Alkalinity (mg/l as CaCO3) SW Alkalinity (mg/l as CaCO3) TW Hardness (mg/l as CaCO3) SW Hardness (mg/l as CaCO3) TW Chlr-a (mg/l) SW Chlr-a (mg/l) TW SUVA (at 254 nm) SW SUVA (at 254 nm) TW Copyright 2012 American Water Works Association. All Rights Reserved. Page 8

10 10. Experience T&O? This survey indicated that 44% of the utilities face taste-and-odor issues. These utilities completed the following questions. For the utilities that said no to this question, the survey was terminated. About 1% of the utilities were not sure if they have T&O issue and hence completed the following questions as well. 11. Odors in treated water The main types of odors detected in the drinking water were identified as earthy, musty and chlorinous odors. Even though the utilities indicated that the data that dated back more than 5-10 years is not very reliable, an increasing trend in these odors over the last two decades is observed. 100 Odors in Treated Water Earthy Musty Chlorinous Grassy Fishy Rotten egg/sulfide Petroleum Plasticy Rubbery Rancid Septic Medicinal Cucumber Fruity Swampy/Decaying vegetation Chemical Solvent Woody Other, please specify # of responses This year 2 to 5 Years Ago 5 to 10 Years Ago 10 to 20 Years Ago Copyright 2012 American Water Works Association. All Rights Reserved. Page 9

11 12. Consumer complaints due to odors The odor complaint data indicated that for the majority of the utilities that responded the average number of complaints were less than 10 per year for the common odors (earthy, musty, chlorinous). Additionally, the maximum number of complaints per year received was for the most common odors (earthy, musty, chlorinous) and the data was more equally distributed showing about 20 to 50 complaints per year or more. # of responses Average number of complaints per year <5 5 to to to 50 > 50 Earthy Musty Chlorinous Grassy Fishy Rotten egg Swampy Chemical Solvent Petroleum Plasticy Rubbery Rancid Septic Medicinal # of responses Maximum number of complaints per year <5 5 to to to 50 > 50 Earthy Musty Chlorinous Grassy Fishy Rotten egg Swampy Chemical Solvent Petroleum Plasticy Rubbery Rancid Septic Copyright 2012 American Water Works Association. All Rights Reserved. Page 10

12 13. Tastes in treated water The main types of tastes detected in the drinking water are determined as chlorinous, earthy, musty, metallic and medicinal. Even though the utilities indicated that the data that date back more than 5-10 years is not very reliable, an increasing trend in the most common taste issues is observed. Other taste descriptors include hard, moldy and raw water. 80 Tastes in treated water # of responses This year 2 to 5 Years Ago 5 to 10 Years Ago 10 to 20 Years Ago 14. Consumer complaints due to tastes The complaint data due to tastes indicated that for the majority of the utilities that responded the average number of complaints were less than 10 per year for the common tastes (earthy, musty, chlorinous, metallic). Looking at the maximum number of complaints received for the earthy, musty, and chlorinous tastes, the response data was skewed towards higher numbers of 50 complaints or more per year. Copyright 2012 American Water Works Association. All Rights Reserved. Page 11

13 Average number of complaints per year # of responses Sweet Salty Bitter Sour Metallic Chlorinous Earthy/Musty 0 <5 5 to to to 50 > 50 Other Maximum number of complaints per year # of responses <5 5 to to to 50 > 50 Sweet Salty Bitter Sour Metallic Chlorinous Earthy/Musty Other 15. Frequency of T&O episodes The number of T&O episodes reported by utilities for average and maximum conditions are tabulated below. Based on the last 5 years of data, about 8 of the participating utilities reported less than 10 episodes per year on average; however, the maximum numbers of complaints reported by of the utilities were between 30 to 500. A slight increasing trend was observed for the recent number of episodes compared to the data from 10 and 20 years ago. It may be that the utilities were confused about how to define an episode in the past, as well as unable to provide quality data from two decades ago. Copyright 2012 American Water Works Association. All Rights Reserved. Page 12

14 T&O episodes per year Minimum # Maximum # Median # Average # Avg last 5 yrs Avg 5-10 yrs Avg yrs Max last 5 yrs Max 5-10 yrs Max yrs Is there an increasing trend of T&O episodes? The utilities that replied yes (15%) to this question indicated changes to the source water and algal blooms were the reason for increased T&O episodes, however the majority (65%) replied no to this question or not sure. Have you noticed an increasing trend in T&O episodes? 15% 65% Yes No Not sure Copyright 2012 American Water Works Association. All Rights Reserved. Page 13

15 17. Probable causes of T&O in source and tap waters The main causes of T&O in source and tap waters were reported as algal blooms, disinfectant residual and plumbing, followed by the distribution system, lake turnover and decaying vegetation. Other causes were identified as: Spring runoff Agricultural runoff Tar lined pipes Annual free chlorine flush Tank maintenance Water age New carpeting Zebra mussels Hydrogen sulfide in ground water Customers switching from well water were unaccustomed to chlorine % of responses Likely causes of T&O in source and tap waters 66% 57% 44% 32% 34% 21% 11% 14% 8% 1% 2% 1% 4% 13% Copyright 2012 American Water Works Association. All Rights Reserved. Page 14

16 18. Probable causes of T&O in the distribution system Domestic plumbing, corrosion and biofilm growth were reported as the main reasons for the T&O issues related to the distribution system. Also new pipe installations and coal tar enamel lined mains were listed as other T&O causing items. % of responses Likely causes of T&O in the distribution system 9% 25% 52% 52% 73% 11% 43% 7% Copyright 2012 American Water Works Association. All Rights Reserved. Page 15

17 19. Severity of the T&O episodes Utilities reported that their T&O episodes were mostly minor, and the responses were relatively uniform for the other severity ratings for data up to 10 years ago. However, the data suggests that the severity of the episodes were much higher 10 to 20 years ago. 10 Severity of T&O episodes % of responses % 5 42% 34% 3 21% 17% 16% 17% 16% 11% 13% 7% 9% 5% 6% 5% 4% 6% 1 (minor) 2 3 (moderate) 4 5 (severe) This year 2 to 5 years ago 5 to 10 years ago 10 to 20 years ago 20. T&O episode prone seasons The data indicates that winter is the least likely season for T&O episodes whereas summer and fall were reported as more severe T&O episode prone seasons. Spring was also noted as a moderate T&O episode occurring season. The results for this question correlates well with the top likely cause of the T&O episodes which was indicated as algal blooms that usually occur during summer and fall months. Copyright 2012 American Water Works Association. All Rights Reserved. Page 16

18 % of responses T&O episode prone seasons 55% 51% 52% 47% 45% 34% 27% 24% 13% 11% 6% 4% 7% 2% 1% None Minor Moderate Severe Summer Fall Winter Spring 21. Duration of T&O episodes Based on the responses obtained for the duration of T&O events, it was determined that for most utilities minor episodes last less than 2 weeks following a similar trend for average episodes. However, severe episodes usually last longer than 2 weeks. The longest duration of a T&O episode was reported as 1 year % Duration of T&O episodes % of responses % 27% 24% 34% 21% 5% 16% 29% 14% 7% 23% Minor Average Severe < 1 week 1-2 weeks 2-4 weeks > 4 weeks Copyright 2012 American Water Works Association. All Rights Reserved. Page 17

19 22. Noticed a significant change in recent T&O episodes? Similar responses were obtained for question 16 above. The main reason for T&O episodes was identified as algae outbreaks. Utilities elaborated on their techniques to reduce T&O by applying lake management practices, dissolved air floatation, activated carbon, ozonation, and chlorine dioxide. Have you noticed a significant change in T&O episodes? 11% 68% 21% Yes No Not sure 23. Importance of handling T&O issues It was determined that, on average, about 6% of utilities do not pay attention to handling T&O issues. However, 77% of the utilities take it very seriously. How Important is handling T&O issues? 3% 3% 1 (not important) 51% 17% 26% 2 (slightly important) 3 (moderately important) 4 (quite important) 5 (extremely important) Copyright 2012 American Water Works Association. All Rights Reserved. Page 18

20 24. Does your facility have a public relations program? Reflecting a similar response as the question above, 69% of the utilities indicated that they have a public relations program to reach out to their customers and handle their concerns and complaints. 25. How do you handle customer complaints and explain T&O issues to consumers? The majority of the utilities explain the situation to the consumer on the phone and collects and analyzes samples from their tap. The utilities also indicated that they follow up with the customers afterwards to make sure the problem is solved. About a third of the utilities also send a newsletter or issue a news release to inform their consumers. How do you handle consumer complaints? % of responses % 16% 26% 46% 77% 4% 16% Answer options: Ignore the complaints as you cannot take any actions Explain the issue to the customer on the phone Send a newsletter to the consumers to explain the issue (before or after it happens) Copyright 2012 American Water Works Association. All Rights Reserved. Page 19

21 Issue a news release to the local paper/tv station Follow-up with the consumers after the issue is resolved Take samples from the consumer(s)' house(s) and conduct sensory and/or analytical analyses Update website, Facebook or other social media Other, please specify: These responses included: handle by flushing the distribution system pipes and handle by activated carbon treatment. 26. How do you record complaints? The majority of the utilities utilize an online system to record their complaint data in conjunction with keeping hard copies. Other responses included creating and compiling data in one excel spreadsheet or not recording the data at all How do you record/archive complaints? % of responses % 42% 67% 1 4% Record it on a Record it on a piece notebook by hand of paper and place in the complaints folder Record it on an online system electronically Other, please specify 27. Do you record T&O complaints separately to be retrieved later? About two-thirds (63%) of the utilities indicated that they record the T&O related complaints separately in order to retrieve them at a later date. This practice aids in being able to trend and track T&O related issues, generally by season. Copyright 2012 American Water Works Association. All Rights Reserved. Page 20

22 28. Do you use standard descriptors for T&O complaints? The majority (61%) of the utilities use standard descriptors for recording their T&O complaint data. The most common standard descriptor combinations used were: Earthy Musty Chlorine Fishy Other standards used in survey that were also noted included: Cat urine Kerosene Algae Dirt The following three questions were asked per request from EPA because AWWA and EPA are launching a program to track consumer complaints as a tool to detect intentional contamination of drinking water. 29. Are you aware of the USEPA s efforts to use consumer complaints as an indication of contamination? Aware of USEPA's efforts to use complaints as contamination indicator? 48% 15% 37% Yes No Not sure Copyright 2012 American Water Works Association. All Rights Reserved. Page 21

23 30. How likely would you be to implement a system that tracks customer complaints? Would implement surveillance program or system to track customer complaints? 42% 14% 4% 11% 29% Very Unlikely Unlikely Undecided Likely Very Likely 31. If you were to implement the system above, how desirable would the built in features (work management, voice recording, GIS, etc.) be? For surveillance program, how important are built in features? 14% 41% 45% Not at all Somewhat Very Copyright 2012 American Water Works Association. All Rights Reserved. Page 22

24 32. Did your facility undergo a major treatment process within the last two decades to handle T&O better? About half (47%) of the drinking water utilities indicated that they have updated their treatment processes to better handle T&O issues. Major treatment process updates included building or addition of: Whole new facilities Dissolved air flotation Ozonation Granular activated carbon layer to the filter Powdered activated carbon feed Biofiltration Membranes (nanofiltration, microfiltration) Reverse osmosis softening treatment New potassium permanganate building Copper sulfate addition to the reservoir Switched to chloramines Switched to a different source water Changed intake location 33. Treatment methods and their efficiency to remove T&O The top three T&O removal treatment methods reported were filtration, flocculation and powdered activated carbon. The least applied treatment methods included super chlorination, UV, softening and chlorine dioxide. Ozonation, GAC/PAC, and post chlorination were reported to achieve more than 75% removal of the T&O. Softening, ph adjustment and corrosion inhibitor application were reported as not efficient methods. Other methods employed by a few of the utilities include dissolved air flotation, permanganate oxidation and purchasing water from another utility. Copyright 2012 American Water Works Association. All Rights Reserved. Page 23

25 60 50 Employed treatment methods # of responses Blend source waters Pre-sedimentation Aeration Rapid mix / flocculation Pre-chlorination Filtration ph adjustment Softening Granular activated carbon Powdered activated carbon Potassium permanganate Super chlorination Post chlorination Chloramines Ozonation UV Hydrogen dioxide Chlorine dioxide Ion exchange softening Membrane filtration Corrosion inhibitor Other, please specify Copyright 2012 American Water Works Association. All Rights Reserved. Page 24

26 25 Most effective treatment method # of responses Blend source waters Pre-sedimentation Aeration Rapid mix / flocculation Pre-chlorination Filtration ph adjustment Softening Granular activated carbon Powdered activated carbon Potassium permanganate Super chlorination Post chlorination Chloramines Ozonation Chlorine dioxide Membrane filtration Corrosion inhibitor UV Other, please specify Copyright 2012 American Water Works Association. All Rights Reserved. Page 25

27 Treatment Efficiencies reported (min/max/average) as: Blend source Presedimentation Rapid mix / waters % % Aeration % flocculation % Min 10 Min 5 Min 10 Min 10 Max 95 Max 80 Max 80 Max 95 Average 58.2 Average 40 Average 40 Average 59 Pre-chlorination % Filtration % ph adjustment % Softening % Min 5 Min 5 Min 0 Min 5 Max 100 Max 100 Max 5 Max 5 Average 46 Average 45 Average 8 Average 5 GAC % PAC % Potassium permanganate % Post chlorination % Min 10 Min 5 Min 50 Min 0 Max 100 Max 100 Max 90 Max 100 Average 82 Average 69 Average 60 Average 67 Chloramines % Ozonation % Chlorine dioxide % Membrane filtration % Min 20 Min 90 Min 25 Min 20 Max 100 Max 100 Max 50 Max 100 Average 62 Average 96 Average 37.5 Average 63 Corrosion inhibitor % Min 0 Max 5 Average 2.5 Copyright 2012 American Water Works Association. All Rights Reserved. Page 26

28 34. Do you apply any preventive methods? Only about one-third (29%) of the utilities apply preventive methods to reduce T&O issues. The most common method is application of algicide and the other methods are given below. % of responses Preventative methods employed 74% 41% Algicide Aeration Hypolimnetic aeration 15% 15% Other The most common algicides used are: Copper sulfate PAK 27 Cutrine Aeration was used as a preventative method for reasons such as: Stratification TTHM s To increase DO levels To control H2S levels Hypolimnetic aeration was used to prevent stratification and increase DO Other preventative methods used: Active mixing KMnO4 PAC Source water blending Copyright 2012 American Water Works Association. All Rights Reserved. Page 27

29 35. Annual cost of handling T&O ( in US Dollars) Based on the limited data provided by the utilities, the expenditures based on severity of the T&O episode follow a weak trend. The data indicates that even severe episodes may be handled with a low budget. The cost data gathered for other components of handling T&O episodes are presented below. % of responses Handling consumer complaints ($) 23% 16% 19% 13% 11% 11% 6% < $50 $50 - $100 $100 - $500 16% 13% 6% $500 - $ % 25% $ $ % 44% > $5000 Minor Average Severe Sensory or instrumental analysis costs ($) % of responses % 35% 31% 4% 5% < $50 $50 - $100 15% 17% 15% 1 13% 8% 1 1 8% $100 - $500 $500 - $1000 $ $ % 23% 8% $ $ % 8% 4% > $25000 Minor Average Severe Copyright 2012 American Water Works Association. All Rights Reserved. Page 28

30 % of responses % 38% 33% Preventive method related costs ($) < $50 $50 - $100 $100 - $500 11% $500 - $ % 12% 12% $ $ % 46% $ $ % 11% 6% > $25000 Minor Average Severe About 1 of the utilities indicated that they spent $50,000 to $4.5 million dollars in capital costs to update their treatment units to handle T&O issues. % of responses Treatment: operational and maintenance costs ($) 46% 25% 24% 25% 25% 6% <$1000 $1,000 - $10,000 21% 24% 18% 15% 15% $10,000 - $50,000 $50,000 - $100,000 12% 5% $100,000 - $500,000 18% 15% 8% > $500,000 Minor Average Severe Copyright 2012 American Water Works Association. All Rights Reserved. Page 29

31 36. Tests to monitor T&O issues About a third (29%) of the utilities do not conduct any testing to monitor T&O issues; however, the rest of the utilities employ sensory, instrumental and biological testing (alone or in combination with each other) to help stay on top of T&O issues. % of responses Testing used to monitor T&O 48% 46% 26% 6% 29% Other tests to monitor/detect T&O issues include: Source water monitoring Customer monitoring 37. Regular testing for specific T&O compounds More than a third (38%) of the utilities test for specific T&O compounds such as: Geosmin 2-MIB Iron Chlorine residual Algae Chlorophyll-a Copyright 2012 American Water Works Association. All Rights Reserved. Page 30

32 38. Sensory methods About 40 % (69 responses) of the utilities responding to this survey reported that they conduct sensory methods to test for T&O. Most of the utilities (85%) that conduct sensory testing employ the threshold odor number (TON) test as their main sensory test. Other more elaborate testing methods, such as flavor profile analysis (FPA), are used by a lot fewer utilities. Other methods conducted were reported as informal smell surveys and staff T&O panels. % of responses Sensory methods used to test for T&O compounds 85% 4% 2% 19% 9% 13% The utilities indicated that the most effective method to test for T&O is the threshold odor number, followed by the FPA. Copyright 2012 American Water Works Association. All Rights Reserved. Page 31

33 Most effective method for sensory T&O testing 2% 4% Threshold Odor Number (TON) 7% 2-of-5 Test Triangle Test 21% Flavor Profile Analysis (FPA) 56% Attribute Rating Test (ART) Flavor Rating Assessment (FRA) 4% 6% Other, please specify 39. Sensory methods used for each treatment stage The most common sensory methods employed to detect the T&O of the samples from different stages of water treatment were TON, followed by FPA, as shown in the previous question above. 40 Methods used for each stage # of responses TON 2-of-5 Triangle FPA FRA Other (as stated above) Source water Treated water Samples from the treatment units Samples from the distribution system Samples from the consumers' taps Copyright 2012 American Water Works Association. All Rights Reserved. Page 32

34 40. Frequency of sensory testing During a T&O episode, the majority of the utilities (78%) conduct daily sensory testing. During T&O prone seasons more than half of the utilities continue their daily testing and more than a quarter perform testing twice a week. The rest of the time a considerable number (4) of the utilities continue performing daily sensory testing. % of responses % 52% 4 Every day 27% 19% 17% 14% 11% 6% 1 4% 7% 2% 2% Twice a week Frequency of sensory testing Once a week Twice a month Once a month 6% 2% Every three months 2% Every six months During an episode Generally T&O episode prone season(s) 41. Do the sensory test results correlate with consumer complaints? Utilities indicated that when they detect off-flavors in the raw or finished water they are very likely to get complaints. However some of them indicated that the masking effect of higher levels of chlorine in the finished water may lead to false results, preventing them from detecting the T&O before the consumers. Do the sensory test results correlate with consumer complaints? 33% 47% Yes No Not sure Copyright 2012 American Water Works Association. All Rights Reserved. Page 33

35 42. Results for the sensory tests TON - Source Water 10 # responses to 2 2 to 4 4 to 8 8 to to to to to 256 Normal T&O Episode TON - Treated Water 10 # responses Normal T&O Episode to 2 2 to 4 4 to 8 8 to to to 64 TON - Distribution system # responses to 2 2 to 4 4 to 8 8 to 16 Normal T&O Episode Copyright 2012 American Water Works Association. All Rights Reserved. Page 34

36 # responses TON - Consumers' tap 1 1 to 2 2 to 4 4 to 8 Normal T&O Episode 43. Chemical/analytical tests About half of the utilities that completed this survey (84 utilities) indicated that they conduct chemical tests for T&O. As illustrated by the results below, 48% of the utilities do the tests in their own lab and another 48% send the samples to an outside lab. A small portion of them use a combination of outside resources and their own labs. Conduct in house tests or send to outside lab? 4% 48% 48% Conduct tests in the facility's lab Send the samples to an outside lab Other, please specify 44. Analytical methods used by the utilities Based on the limited responses (by only 30 utilities) to this question, the common/popular analytical method to test for volatile organics is determined as solid phase micro-extraction coupled with gas chromatography/mass spectrometry. Copyright 2012 American Water Works Association. All Rights Reserved. Page 35

37 12 Analytical methods used # of responses Methods and instruments used by the outside laboratory Utilities were almost evenly split for this question and reported that they either know the methods and instruments used by the outside lab (47%) or they do not (53%). The methods used by the laboratories were reported as solid phase micro-extraction coupled with gas chromatography/mass spectrometry or closed loop stripping. 46. T&O compounds detected in source or treated water The utilities reported several compounds that were detected/measured in their source and treated waters. The reported compounds and their concentrations are given below. Other compounds measured/detected were reported as limonene, propanol, naphthalene, mycrocystis and an unidentified compound. Copyright 2012 American Water Works Association. All Rights Reserved. Page 36

38 Detected T&O compounds # of responses Concentrations during average conditions: Free chlorine (mg/l) Chloramines (mg/l) Geosmin (ng/l) 2-Methylisoborneol (ng/l) Min 0 Min 0 Min 0 Min 0 Max 3 Max 2.8 Max 13 Max 15 Average 0.93 Average 1.88 Average 5.7 Average 5.2 Responses 24 Responses 9 Responses 20 Responses 18 Iron (mg/l) Copper (mg/l) Manganese (mg/l) Min Min Min Max 0.3 Max Max 2 Average 0.12 Average Average 0.3 Responses 10 Responses 6 Responses 9 Concentrations during high conditions: Free chlorine (mg/l) Chloramines (mg/l) Geosmin (ng/l) 2-Methylisoborneol (ng/l) Min 0.2 Min 2.3 Min 8 Min 1 Max 3.4 Max 5.1 Max 4,600 Max 400 Average 1.8 Average 3.5 Average 411 Average 78.5 Responses 19 Responses 10 Responses 23 Responses 21 Iron (mg/l) Copper (mg/l) Manganese (mg/l) Min Min Min Max 2.1 Max 1.5 Max 8 Average 0.5 Average 0.5 Average 1.5 Responses 8 Responses 4 Responses 7 Copyright 2012 American Water Works Association. All Rights Reserved. Page 37

39 Concentrations after treatment: Free chlorine (mg/l) Chloramines (mg/l) Geosmin (ng/l) 2-Methylisoborneol (ng/l) Min 0.05 Min 1.8 Min 2 Min 0 Max 2.5 Max 3.5 Max 30 Max 26 Average 1.3 Average 2.5 Average 8.7 Average 6.3 Responses 9 Responses 11 Responses 13 Responses 12 Iron (mg/l) Copper (mg/l) Manganese (mg/l) Min 0 Min 0.05 Min 0 Max 0.3 Max 0.05 Max 0.05 Average 0.1 Average 0.05 Average Responses 4 Responses 1 Responses Algal toxins Fifty-six utilities responded to this question and only 12 of them indicated that they test for algal toxins. The commonly tested toxins include cyanotoxins and microcystins. 48. Frequency of analytical testing During a T&O episode, the majority of the utilities conduct analytical testing at least once a week. Under normal conditions, once a week and once a month are the most common sampling frequencies. Utilities mostly conduct analytical testing during T&O episode prone season(s) once a week. Copyright 2012 American Water Works Association. All Rights Reserved. Page 38

40 10 Frequency of analytical testing % of responses % 21% 26% 17% 13% 11% Every day 3% Twice a week 42% Once a week 32% 14% 11% 14% 7% 5% 2% 4% 4% Twice a month Once a month Every three months Every six months Once a year During an episode Generally T&O episode prone season(s) 49. Biological testing Thirty-seven utilities (about ) reported that they conduct biological tests to monitor T&O issues. The utilities mainly perform algae counts and identification. The responses to this question were limited, but the data collected indicates that algae are the more common cause of T&O. Other methods include testing for zooplankton. Copyright 2012 American Water Works Association. All Rights Reserved. Page 39

41 Biological tests performed % of responses % % Plankton testing Benthic organism testing Algae counts and identification Other, please specify 50. Monitor specific types of algae to monitor T&O? The majority of the utilities (78%) that conduct biological testing monitor for specific types of algae. The specific algae types include: Blue green and/or flagellated algae Diatoms 51. Organisms detected and identified as causing T&O Based on the responses to question 50, organisms detected and identified as causing T&O were: Blue green algae Synura Ceratium Anabaena Chrysopherella Staurastrum Mycrocytis Asterionella Mallomonas Ocsillatoria Synedra Aphanizomenon Copyright 2012 American Water Works Association. All Rights Reserved. Page 40

42 52. Frequency of biological testing The most common frequency for biological testing under all conditions was reported as once a week. As expected, the frequency increased to every day during a T&O episode. 10 Frequency of biological testing 9 8 % of responses % 9% 6% 27% 5% 17% 36% 32% 5 5% 17% 14% 41% 11% During an episode Generally T&O episode prone season(s) Every day Twice a week Once a week Twice a month Once a month Copyright 2012 American Water Works Association. All Rights Reserved. Page 41

43 SUMMARY AND IMPORTANCE OF FINDINGS This T&O survey provides valuable information for drinking water utilities to understand the main causes of T&O occurrences, and to help determine the most efficient and cost effective methods to handle episodes. The data gathered by this survey indicated that almost one-half of the utilities face some form of T&O issues. The common odor descriptors in treated water included chlorinous, earthy and musty. The common taste descriptors were similar to odors, with the addition of a metallic taste. Even though a clear trend was difficult to observe from the collected data due to changes in source water, types of treatment processes, and other outside factors, the presence of tastes and odors in treated water show an increasing trend over the last two decades. The major cause of taste and odor issues were linked to disinfectant residual, algal blooms and distribution system/plumbing materials. Approximately 75% of the utilities reported that their T&O episodes were mostly minor. Summer and fall months were indicated as T&O prone seasons with average T&O episode durations usually less than 1-2 weeks. Even though the surveyed utilities do not experience serious T&O issues often, being able to handle T&O episodes is very important to them. The survey participants use many methods to reach out to the customers, including newsletters, news releases and websites. These methods are used to inform their customers when a T&O episode has occurred and to help explain why the episode happened, which the utilities find helps to maintain confidence with their customers. The best treatment methods reported for T&O control are filtration, flocculation and activated carbon treatment. Approximately 3 of the utilities take preventive actions such as the use of algicides and aeration of their source waters. While the cost to handle complaints, conduct analyses and apply preventive methods is anywhere from $50 to $25,000 annually for utilities, the treatment related costs increased to more than $500,000 per year in some cases for even minor T&O issues due to treatment updates and upgrades. Some form of sensory, chemical and/or biological testing is employed by approximately 7 of the utilities. The most commonly investigated compounds include algal odorants (geosmin and 2-MIB), iron, manganese and copper. Threshold odor number was used to evaluate the odors in source and treated waters and was indicated as the most effective method for T&O analysis, followed by flavor profile analysis. Copyright 2012 American Water Works Association. All Rights Reserved. Page 42

44 Utilities were evenly split between conducting their own tests or using outside laboratories for chemical analyses. Volatiles were analyzed by solid phase microextraction coupled with gas chromatography/mass spectrometry. Biological testing focused on algal identification or counting. Blue-green algae (cyanobacteria) were identified as the most problematic algae for T&O related issues. The testing frequency increased to almost every day during a T&O episode, and conducted more frequently during T&O prone seasons. Utilities serving 21 st century customers have higher standards to meet because the customers not only expect the tap water to be safe, but also to be pleasant tasting. Fortunately, utilities now have access to improved detection and treatment techniques to handle T&O issues. The data gathered by this survey indicates that the use of preventive methods and sensory and analytical techniques coupled with efficient treatment methods will allow utilities to provide better tasting water to their customers. SUGGESTIONS FOR FUTURE T&O SURVEYS Online surveys work well, however, ing the full survey as a word document or PDF allows the responders the option to collect data on their own time and could enhance contributions. Refine the survey questions and minimize the number of questions. Provide clear cut answer options and define terms when appropriate. Allow at least nine months for completion of the survey. Calling and sending reminders to the potential responders help improve the response rate. ACKNOWLEDGEMENTS We would like to thank our Program Manager, Liz Ralph, for her support, input and guidance throughout the project. We also thank Ari Copeland for reviewing the report. Copyright 2012 American Water Works Association. All Rights Reserved. Page 43