A randomized, double-blind water taste test to evaluate the equivalence of taste between tap water and filtered water in the Taipei metropolis (original) (raw)
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Understanding the basics of tap water taste
2007
ABSTRACT n many ways tap water is similar to food and beverage products sold at the grocery store. It has a shelf life (i.e., changes in quality can occur over time), a preservative (i.e., a disinfectant residual), and packaging (e.g., pipes, plumbing, storage tanks). As long as we sup-ply drinking water through a public water supply system, we have the responsibility to consider its acceptability for human consumption—even though only a small percentage of tap water is used for drinking. Although a lack of acceptance of tap water flavor will not likely affect water production, it can be a major factor in public trust and confidence. Therefore, having an understanding of how the sensory properties of tap water are perceived is important for customer relations (Dietrich, 2006). Despite the strong relationship between taste and acceptability, the con-nection between drinking water taste, water quality, and water treatment has received little attention. As water treatment techniques become more effective at removing constituents from water—such as with desalination and membrane processes—the effect of water treatment on water taste is becoming more important. Anions and cations, including the hydrogen ion, are largely responsible for the taste sensations at the cellular level of the taste buds. In water, anions and cations occur as a multifaceted "soup" of free ions, complexes, and even particulate matter. Ions are present simultaneously and interact depend- 101 ing on concentration, pH, pE, tem-perature, and thermodynamic sta-bility constants. For example, cop-per can be present as the free cupric ion Cu +2 ; it can bind with anions to form hydroxo complexes (e.g., CuOH +), carbonato complexes (e.g., CuCO 3 0), and chloride complexes (e.g., CuCl +); or it can occur as the precipitate copper II hydroxide. The taste perception of these different ion species has yet to be thoroughly investigated or understood. Thus, references on what affects taste vary between reporting levels of ions and levels of minerals and salts. A literature review was con-ducted to explore how "taste" is determined, how the levels of min-erals (cations and anions) that occur in natural waters and saliva influ-ence the taste of water, how existing standards address taste, how water treatment can affect taste, and whether more research is needed. The results of this review will pro-vide drinking water practitioners, treatment designers, researchers, and regulators with a better under-standing of how their decisions can affect the taste of tap water. Included is an overview of the human senses with regard to water flavor.
Materials used in drinking water distribution systems: contribution to taste-and-odor
Water science and technology : a journal of the International Association on Water Pollution Research, 2004
In order to assist drinking water utilities with identifying the possible sources and causes of taste-and-odor conditions associated with materials used in distribution systems, we evaluated information from case studies and a database from the National Sanitation Foundation (NSF), International. This database identified chemicals that had leached from drinking water system components during testing of materials under ANSI/NSF Standard 61, which provides information to water utilities on potential taste-and-odor and health concerns from the use of new materials. The data were arranged to provide a process for locating the potential source of a taste-and-odor event. After a sensory analysis is conducted on the drinking water samples, the descriptor can be matched with categories on the "Drinking Water Taste and Odor Wheel 2000" in order to suggest the candidate material.
Water science and technology : a journal of the International Association on Water Pollution Research, 2004
A workshop of international drinking water experts was convened in Sedona, Arizona, March 26-27, 2001 for the purpose of developing a method for testing drinking water system components for their potential to contribute to taste-and-odor problems in drinking water. The workshop participants derived a method using provisions from European Standards as well as newly developed approaches. It is intended that this method can serve as a temporary procedure for water utilities, as well as a recommended template to derive an official standard. Materials to be tested may include pipes, fittings, ancillaries, joints, lubricants, tanks, and reservoirs. The recommended method includes a migration (leaching) test with chlorinated water, followed by sensory analysis of the samples from the migration test after dechlorination. Sensory analyses use both statistical (e.g., triangle test) and descriptive (e.g. Flavor Profile Analysis) techniques. A decision tree for the results is provided.
Two different profiles of aroma and flavor of salt (NaCl) and free chlorine or chloramine in drinking water were evaluated. The first profile studied the effect of the different concentrations of salts with or without constant concentrations of chlorine or chloramine on salt taste in drinking water. This study indicated that minimum threshold salt concentration should range between 650 to 850 mg/L in drinking water. The second profile studied the effect of different concentrations of free chlorine or chloramine with or without constant salt concentrations on chlorine or chloramine tastes in drinking water. Tests on potential Tucson tap water from the Central Arizona Project (CAP) and Central Avra Valley ground water in Tucson were completed and compared to laboratory studies by Flavor Profile Analysis (FPA). The FPA's evaluations of the free chlorine, chloramine, and three different waters (AVRA, CAP, and 50:50 blends of the two waters) indicate that trained FPA panels studying chlorine taste should used chlorine free bottle water containing similar salts and minerals to the water of CAP and AVRA. FPA analyses of free chlorine in MilliQ water and in CAP water point out a synergistic effect contribute by other minerals of CAP water for the intensification of chlorine test. Actual mineral content of drinking water and not just Sodium Chloride (NaCl) is needed for comparative flavor tests. The analysis of real water samples with different content of salts and minerals indicates no minimum starting concentration of free chlorine and NaCl contributes to negative dose-response curves for free chlorine taste as was seen by FPA panel in Milli-Q water with different free chlorine concentrations and no salt.
Journal of Water Resources and Ocean Science, 2020
Background: Drinking water should be harmless to its consumers and aspects such as appearance, taste and/or odor should be acceptable. In Burkina Faso, the sold bottled and sachet drinking waters are not always respecting the quality in terms of potability. Method: In this study we investigated the appearance, taste and/or odor of eleven (11) selected bottled and sachet waters sold in Burkina Faso through a set of five (05) water treatment professionals with ten (10) organoleptic parameters been considered (Organic Solvent, Metallic, Chlorine, Fishy, Sulfur, Earthy, Bitter, Fruity, Spoiled, and Sour). Results: The study showed that all the investigated waters have unpleasant taste and/or odor, with the worst cases in all five (05) brands sachet waters. The bad quality of the sachet waters is generally due to the conditioning (sun, dust, rain). Ouagadougou tap water showed unpleasant chlorine odor mainly caused by the "remanent" chlorine. However, that chlorine ensure the water safety to its consumers. Conclusion: This study showed that the best way to drink safe water in Burkina Faso is to supply a good quality tap water to its population, and to improve the taste and/or odor. Since the sold bottled and sachet waters are not yet well regulated in terms of their quality, the country should be aware of the current study in order to improve the sold drinking water quality.
Characteristics of salt taste and free chlorine or chloramine in drinking water
Water Science & Technology, 2007
Salty taste with or without chlorine or chloramine flavour is one of the major consumer complaints to water utilities. The flavour profile analysis (FPA) taste panel method determined the average taste threshold concentration for salt (NaCl) in Milli-Q water to be 640±3 mg/L at pH 8. Chlorine and chloramine disinfectants have no antagonistic or synergistic effects on the taste of NaCl, salt, in Milli-Q water. The flavour threshold concentrations for chlorine or chloramine in Milli-Q water alone or in the presence of NaCl could not be estimated by the Weber-Fechner curves due to the chlorine or chloramine flavour outliers in the 0.2–0.8 mg/L concentration range. Apparently, NaCl is not equilibrated with the concentration of ions in the saliva in the mouth and the concentration of free chlorine or chloramines cannot be tasted correctly. Therefore, dechlorinated tap water may be the best background water to use for a particular drinking water evaluation of chlorine and chloramine thres...
Comparative Quality Analysis between Tap Water and Bottled Water
ARO-THE SCIENTIFIC JOURNAL OF KOYA UNIVERSITY
Recently, bottled water consumption has been increasing significantly, even when the quality of tap water is considered excellent, which contributes to plastic pollution. Besides, reducing the use of plastic generally is recommended world widely, as its consumption is in an alarming rate. Therefore, this study aims to compare the tap and bottled water and manifest the reasons behind choosing the bottled water, which is less comfortable and often more expensive over the tap water. In this study, samples have been taken from both bottled and tap water in Koya city from November 2020 to May 2021 to test their quality using PH, DO, EC, and TDS meter, hardness was determined by complexometric titration method at 21°C, and XRF spectrometers. According to the quality standards, most of the variables were in a permissible range, except for dissolved oxygen and Aluminum content in both types of water and TDS for two types of bottled water. However, the quality of tap water was much safer to ...
Sensory properties of Danish municipal drinking water as a function of chemical composition
Food Research International, 2013
Studies have shown that drinking water of good sensory quality have total dissolved solid (TDS) concentrations between 100 and 450 mg L −1 . However, such studies have only investigated the overall sensory quality of water and not the different sensory attributes. Little is known about the taste and mouthfeel attributes of drinking water in relation to the chemical composition. The purpose of this study was to determine the variation in sensory attributes of Danish drinking water and the relation to the chemical composition. Groundwater samples were collected from 20 waterworks with uplands and aquifer reservoirs characteristics covering the main variation in geochemistry and land use. The groundwater samples' inorganic chemical composition was determined and a trained panel determined sensory attributes and their intensities. Identified sensory attributes listed with decreasing intensity were: moist, fresh, salty, chalky, hard, astringent, metallic, bitter, sweet and sour. The main sensory variation between samples was caused by the saltiness and this attribute was negatively correlated to all other impressions especially moistening. The saltiness had a strong linear positive correlation to the TDS, conductivity and Na concentration (R 2 = 0.72-0.92) whereas the descriptor fresh was negatively linear correlated to these parameters (R 2 = 0.76-0.81). The descriptors, fresh and moist, seem mainly to be a result of low salt concentrations which characterises samples from aquifers at the glacial outwash plains of western Jutland and elevated seabeds of northern Jutland.
2013
may be freely shared among individuals, but it may not be republished in any medium without express written consent from the authors and advance notification of the editor. Key Words: Categorical data, inference for a single proportion, chi-square goodness-of-fit test, chi-square test for independence. In this paper we present data collected from two water taste tests conducted at Longwood University in the fall of 2008. These data are appropriate for performing exploratory data analyses and inference using the test for a single proportion and chi-square tests, including the goodness-of-fit test and the test for independence. The data also provide opportunities for students to consider the cell-count assumptions for chi-square tests, as some tests meet the assumptions and others do not. Finally, the results from the taste tests raise questions about sustainability issues related to consumer preference, bottled water consumption, and its environmental impacts. 1.