PET-Bottled Water Consumption in View of a Circular Economy: The Case Study of Salento (South Italy)

: Polyethylenterephtalate (PET) is the preferred packaging material in the bottled water industry and represents the main cause of waste production. This work investigated the drinking water consumption habits, with particular reference to PET-bottled water, of people living in the province of Lecce (Apulia Region, Southern Italy) by age and geographical groups. Their perception about the quality of tap water was also explored. The survey was performed by the administration of a questionnaire to 4137 citizens. Bottled mineral water was consumed by about the 90.4% of respondents with an average consumption of 387.7 L / year per capita (375.2 L / year in PET-bottles, 12.5 L / year in glass bottles). Public supply system was used by the 61.5% of respondents with an average consumption of 169.4 L / year per capita. The consumption of tap water was negatively related to the perception of its bad quality and the residence in a big city (Lecce); while it was positively associated with the age group ≤ 16 years old. E ﬀ ective communications strategies must be developed in order to promote the consumption of tap water and implement good practice of circular economy.


Introduction
The most common water supply systems for human consumption are tap water and bottled water. The former is distributed by aqueduct and available to consumers by tap, the latter includes the drinking water available on the market in glass or in polyethylenterephtalate (PET) bottles [1]. Lifestyle changes led to the growth of the bottled water market over the last decade, with more and more glass packaging being replaced by plastic packaging [2]. About 4% of the world's oil and gas production is used as a raw material for plastics production and a further 3-4% is spent to provide energy for their production [3]. In addition, most of the plastic produced each year is used to produce short-life packaging that quickly becomes waste that, due to the durability of polymers, degrades slowly in the environment, accumulating and destroying natural habitats around the world. These reflections indicate how the current production and consumption of plastics is unsustainable and new strategies are needed to limit their use. Polyethylenterephtalate (PET) is the commonly used type of plastic and represents one of the main causes of waste production [4]. It is a sturdy material that is long lasting, chemically and thermally stable, and it can be easily recycled. These traits make it suitable order to take into account consumption and wastes management. Specifically, the European Union has suggested to increase the threshold of recycling of plastic packaging up to 55% by 2025 [26]. Furthermore, "the European Strategy for Plastics in a circular economy" aims to reach the 100% of recycled packaging by 2030, considering plastic materials among the five priority goals of actions to implement resource efficiency and reduced their dependence on natural capital. The concept of circular economy involves a production system and consumption in which biological material are replenished in the biosphere, while wastes are reduced, reused, or recycled. This strategy will play a crucial role in the resources management policies and in waste prevention. Many governs and international organizations have strongly promoted this approach, although there is still a long way to reach this goal [27][28][29]. Recycling rate of all plastic packaging, in Italy, is around 43%, confirming to be, in general, a "virtuous country", because 58.1% of wastes are properly differentiated [30]. Moreover, separate collection of wastes varies according to North and South of Italy, in particular Puglia is below the national average (45.4%) [31]. Furthermore, the province of Lecce, compared to the other municipalities of Puglia, showed an average percentage of waste properly differentiated around 41.0%, of which plastic corresponds roughly to 13% of the total amount of waste [31].
In order to reduce the number of plastic bottles, it is necessary to take into account the main reasons which lead consumers' choice towards bottled water supply rather than choosing public drinking water. The data from ISTAT [25] estimated that, the 29% of Italian families, about 7 billion and 500 thousand, does not drink water from public network. Although optimal quality standards are achieved, there is an increase in bottled water sales [32].
The aim of this study was to investigate the consumption of drinking water by the population living in the Province of Lecce with particular reference to the main supplies used and the factors related to the choice of supply including the consumers' perception about the quality and safety of the water from public system. Moreover, the consumption of PET-bottled water was taken into account.

Study Area
The study area is part of the Salento Peninsula (Figure 1), located in the southern part of Puglia, which borders the Adriatic Sea to the east and the Ionian Sea to the south and west. It includes 97 municipalities, extends for 2799.07 km 2 and has a total population of about 800,000 inhabitants.
The hydrology of the Salento peninsula is affected by its geological structure mainly composed of karst terrain, which causes the lack of surface water and a high development of underlying aquifers [33]. These comprise a shallow aquifer occupying only 35% of the territory and an extensive deep aquifer, intensively exploited in the past as a source of drinking water [34] and irrigation water [35]. The deep aquifer is supported by seawater from marine invasion which, in the last few decades, produced the increase in its salinity as a consequence of the increase in the extraction of water for irrigation purposes [36,37]. Moreover, deep aquifer is fed by waters mainly from higher layers and rains, which easily reaches it because of tectonic fractures and sandy layers [38,39]. The poor degree of filtration provided by the terrain and the increase in the spread of pollutants on the surface caused also the chemical and microbiological contamination of groundwater so as to interdict in many cases its use for drinking purposes [40][41][42][43][44][45].

Study Design
The study was part of the M.I.N.O.RE. (Non-Mandatory Regional Water Monitoring) project funded by Apulia Region in order to investigate the qualitative and quantitative state of the groundwater in Salento Peninsula and the consumption of drinking water among the people living in the study area [46].
The survey on drinking water habits was carried out by administering a questionnaire to a sample of citizens living in the Province of Lecce.
A preliminary analysis was performed in order to evaluate the internal consistency of items by the administration of the questionnaire to a restrict group (120 subjects of all ages living in the Province of Lecce). The items that resulted not clear or ambiguous were removed or reformulated. The final questionnaire, drawn up in Italian, included 16 items grouped in 4 main categories: (i) sociodemographic characteristics of the participants (gender, age, educational level, place of residence); (ii) type and daily intake of drinking water (water from public water system, including tap water without any treatment, tap water purified by domestic systems, such as purifier or water softener, and public water cooler, bottled mineral water, water from private wells); (iii) quality and safety perception of drinking water from public supply system; (iv) packaging choice (for bottled water consumers).
In order to verify any differences in relation to the age or geographical origin of the participants, the subjects were grouped into four age groups (≤16 years old, 17-39 years old, 40-64 years old, ≥65 years old) and the territory of the Province of Lecce was divided into ten areas (Campi Salentina, Casarano, Gagliano del Capo, Galatina, Gallipoli, Lecce, Maglie, Martano, Nardò, Poggiardo), corresponding to the Social Health Districts (SHD) (Figure 1).
The survey started in June 2019 and finished in February 2020. The questionnaires were administered in two ways: online, through the Google's platform, or in paper form. In the first case the survey was promoted through social media (Instagram, Facebook), instant messaging

Study Design
The study was part of the M.I.N.O.RE. (Non-Mandatory Regional Water Monitoring) project funded by Apulia Region in order to investigate the qualitative and quantitative state of the groundwater in Salento Peninsula and the consumption of drinking water among the people living in the study area [46].
The survey on drinking water habits was carried out by administering a questionnaire to a sample of citizens living in the Province of Lecce.
A preliminary analysis was performed in order to evaluate the internal consistency of items by the administration of the questionnaire to a restrict group (120 subjects of all ages living in the Province of Lecce). The items that resulted not clear or ambiguous were removed or reformulated. The final questionnaire, drawn up in Italian, included 16 items grouped in 4 main categories: (i) sociodemographic characteristics of the participants (gender, age, educational level, place of residence); (ii) type and daily intake of drinking water (water from public water system, including tap water without any treatment, tap water purified by domestic systems, such as purifier or water softener, and public water cooler, bottled mineral water, water from private wells); (iii) quality and safety perception of drinking water from public supply system; (iv) packaging choice (for bottled water consumers).
In order to verify any differences in relation to the age or geographical origin of the participants, the subjects were grouped into four age groups (≤16 years old, 17-39 years old, 40-64 years old, ≥65 years old) and the territory of the Province of Lecce was divided into ten areas (Campi Salentina, Casarano, Gagliano del Capo, Galatina, Gallipoli, Lecce, Maglie, Martano, Nardò, Poggiardo), corresponding to the Social Health Districts (SHD) (Figure 1).
The survey started in June 2019 and finished in February 2020. The questionnaires were administered in two ways: online, through the Google's platform, or in paper form. In the first case the survey was promoted through social media (Instagram, Facebook), instant messaging application, and our website. Paper questionnaires were administrated in meeting places (supermarkets, church) or distributed in school prior authorization of the principal, and in case of underage participants, questionnaires were filled out by their parents. Schools were chosen on the basis of their centrality within each district.

Sampling Distribution
The survey involved 4137 citizens of the Province of Lecce, whose age and distribution per SHD were reported in the Table 1. The total population interviewed was quite evenly distributed among the first three age groups ≤16, 17-39, 40-64 (27%, 33%, and 30% respectively), while the age group ≥65 represented only the 10% of the total. The density of the respondents was similar in all districts with an exception of the district of Maglie, which showed the highest value (11.0%).

Data Analysis
At the end of the survey, questionnaires were coded and all the information was entered into a Microsoft Excell database. For descriptive statistics and graphical representations data were processed using MedCalc Software version 12.3 (MedCalc Software bvba, Ostend, Belgium). In order to verify if the qualitative and quantitative variables were different distributed among age or geographical groups Chi-square and one-way ANOVA tests were respectively used. A logistic regression analysis was performed to verify any association between the general consumption of tap water (dependent variable) and the negative perception concerning its quality, age group, educational level, house localization and residence area (independent variables); odd ratio (O.R.) and 95% confidence interval (C.I.) were calculated. Differences were considered significant for p < 0.05. QGIS (Quantum Geographic Information System) software was used for geographical representations.

Results
The characteristics of respondents involved in the survey (gender, education level, and residence) were reported in Table 2. Females represented most of the respondents (60.6%), while males accounted for 39.4%. Participants' educational level appeared quite high, since the main part of respondents had a high school diploma (55.0%), 32.7% had a university degree or higher while 10.9% had a middle school diploma. Lastly, only a small part had a primary educational level or no educational level (1.0% and 0.6% respectively). Lastly, most of the participants (85.0%) said they lived in an urban area while 15.0% lived in the countryside. The results highlighted people's trend towards a massive consumption of bottled water. In particular, bottled mineral water was consumed by about the 90.4% of citizens with an average consumption of 387.7 L/year per capita (375.2 L/year in PET-bottles, 12.5 L/year in glass bottles). Public supply system was used for drinking purpose by the 61.5% of respondents with an average consumption of 169.4 L/year per capita, including tap water without any treatment (25.9%), tap water purified by domestic systems (10.7%), and water from public water cooler (24.9%). Water from private wells was used by a limited part of the population (4.7%) while water from other sources (i.e., tanker) was used only by 0.5% (Figure 2). It is interesting to highlight that 41.9% of citizens living in the Province of Lecce, consumed exclusively bottled mineral water, while 7.7% used only water from public supply system, 0.7% from private wells, and 0.1% from other sources. The rest of the respondents (49.6%) said to drink water from mixed supplies.  The results highlighted people's trend towards a massive consumption of bottled water. In particular, bottled mineral water was consumed by about the 90.4% of citizens with an average consumption of 387.7 L/year per capita (375.2 L/year in PET-bottles, 12.5 L/year in glass bottles). Public supply system was used for drinking purpose by the 61.5% of respondents with an average consumption of 169.4 L/year per capita, including tap water without any treatment (25.9%), tap water purified by domestic systems (10.7%), and water from public water cooler (24.9%). Water from private wells was used by a limited part of the population (4.7%) while water from other sources (i.e., tanker) was used only by 0.5% (Figure 2). It is interesting to highlight that 41.9% of citizens living in the Province of Lecce, consumed exclusively bottled mineral water, while 7.7% used only water from public supply system, 0.7% from private wells, and 0.1% from other sources. The rest of the respondents (49.6%) said to drink water from mixed supplies. An analysis about the bottled mineral water consumption was carried out. Considering the packaging choice, 96.7% of mineral water consumers (90.3% of total respondents) declared to buy water in PET bottles, 3.1% in glass bottles, and a limited part (0.2%) utilized both packaging. An analysis about the bottled mineral water consumption was carried out. Considering the packaging choice, 96.7% of mineral water consumers (90.3% of total respondents) declared to buy water in PET bottles, 3.1% in glass bottles, and a limited part (0.2%) utilized both packaging. Table 3 reports the consumption of PET-bottled mineral water by the respondents grouped per age and geographical area. Overall, in the Province of Lecce the average consumption of mineral water in PET bottles was 375.2 L/year per capita with a production of about 200 million plastic bottles per year (considering a population of about 800,000 inhabitants and an average content per bottle of 1.5 L). Significant differences (p < 0.05) appeared between age and geographical groups, with a higher average intake in age group of 17-39 (407.1 L/year) and in the district of Lecce (410.1 L/year), while the lowest values were registered in the older age group (331.2 L/year), and in the district of Poggiardo (326.6 L/year). Concerning the public water supply network, 45.2% of the all respondents did not find any critical issue while 54.8% declared one or more problems: 38.7% considered tap water nasty, 26.4% unsafe, and 5.1% turbid (Figure 3).  Table 3 reports the consumption of PET-bottled mineral water by the respondents grouped per age and geographical area. Overall, in the Province of Lecce the average consumption of mineral water in PET bottles was 375.2 L/year per capita with a production of about 200 million plastic bottles per year (considering a population of about 800,000 inhabitants and an average content per bottle of 1.5 L). Significant differences (p < 0.05) appeared between age and geographical groups, with a higher average intake in age group of 17-39 (407.1 L/year) and in the district of Lecce (410.1 L/year), while the lowest values were registered in the older age group (331.2 L/year), and in the district of Poggiardo (326.6 L/year). Concerning the public water supply network, 45.2% of the all respondents did not find any critical issue while 54.8% declared one or more problems: 38.7% considered tap water nasty, 26.4% unsafe, and 5.1% turbid (Figure 3). Data of drinking water perception were further evaluated on the basis of geographical division of the municipalities in their belonging health districts (SHD). The perception about the quality of public water supply was considered according to the residence of respondents (Figure 4). The Data of drinking water perception were further evaluated on the basis of geographical division of the municipalities in their belonging health districts (SHD). The perception about the quality of public water supply was considered according to the residence of respondents (Figure 4). The prevalence of negative features (nasty, unsafe, or turbid) was not equally distributed among the different SHD (p < 0.005), with the highest level of negative perception in the SHD of Lecce (54.1%), Campi Salentina (54.0%), and Galatina (53.4%).  PET bottled water consumption, on the base of this distribution, showed a homogenous trend in the SHD: on average the 90.4% of respondents confirmed to avail of it. By contrast, drinking water by public supply has heterogeneous distribution < 0.01 in the districts.
The choice of the drinking water typology was likely conditioned by the perception that consumers had about the quality of tap water. In particular, the logistic regression (Table 4)   PET bottled water consumption, on the base of this distribution, showed a homogenous trend in the SHD: on average the 90.4% of respondents confirmed to avail of it. By contrast, drinking water by public supply has heterogeneous distribution (p < 0.01) in the districts.
The choice of the drinking water typology was likely conditioned by the perception that consumers had about the quality of tap water. In particular, the logistic regression (Table 4)

Discussion
This survey allows for the evaluation of the consumption of drinking water by the residents in the province of Lecce, in relation to the supplies they used and the factors influencing their choice.
The data collected by the administration of a questionnaire to 4137 citizens highlighted an annual consumption of bottled water in the Province of Lecce of 387.7 L/year per capita, mostly packaged in PET bottles for a total of 375.2 L/year per capita, while the consumption of water from public supply system (including tap water without treatment, depurated tap water, and water cooler) was 169.4 L/year per capita.
Our results appeared higher if compared with those of other surveys carried out at national and international level and confirmed the general concerns regarding the lack of consumers' faith in public aqueduct and the increase of plastic bottled water consumption. In particular, according to International Bottled Water Association (IBWA) [47], in Italy the annual per capita consumption of bottled water in 2019 was 201.8 L/year with an increase of 12.5% compared to 2014. Other Italian surveys reported an annual per capita consumption of bottled water of 206 L/year in 2015 [48] and 221 L/year in 2018 with a percentage of PET bottled water of 82% [8]. Finally, Tosun et al. [49], reviewing data from several studies, stated that Italy held the first place in Europe for bottled water consumption and the lower position for tap water consumption.
Furthermore, the growth of bottled water consumption might pose serious problems to the management of plastic wastes in the Salento peninsula also in relation to the environmental impact deriving from the close connection of the territory with the sea.
As reported by other authors, understanding why people are preferring plastic bottles is important to reduce harmful habits [50]. In addition to the well-known factors influencing the consumer's choice in favor of PET packaging, such as its low cost and its practical use [51], in the Province of Lecce, there may be other possible explanations regarding the high consumption of PET-bottled water. First of all, the perception of the quality and safety of tap water seemed to be an important factor that influenced the choice of consumers regarding the supply of drinking water. Indeed, most of respondents consider nasty or unsafe water supplied by public network and this resulted in a lower consumption of tap water and higher consumption of PET-bottled water.
This relation between bad quality perception and consumption of tap water has been confirmed too by Tosun et al. [49], in Germany. In addition, the poor quality of groundwater available in the Salento peninsula, which feeds the local public aqueduct [37], could condition the perception of tap water safety and, consequently, the consumers' preference for mineral bottled water. Probably, citizens are not informed about the real quality of tap water and their choice is on the basis of what they perceived as healthier.
Some geographical features also linked to sociocultural factors could influence the choice of drinking water typology. In fact, people living in bigger city as Lecce, consumed less tap water than people living in other areas of the province. This aspect should be investigated through further research in other metropolitan areas to verify whether this trend is typical of large cities.
Age could also influence the type of drinking water. The younger age group consumed tap water in greater quantities and would seem more sensitive to environmental problems probably because they were more involved in school messages regarding waste reduction, with particular reference to plastic waste.
An important concern regarding the PET-bottled water consumption is that, if not properly disposed, the plastic bottles may have a significant environmental impact, especially for the sea. This aspect is particularly relevant for the Province of Lecce, which extends for over 280 km of beaches and coastlines. Moreover, Salento peninsula has become, in the last 10 years, one of the most popular destinations, particularly for foreign tourists, which presumably involves an increase in the production of plastic waste especially close to the coast and in the summer months. At this purpose changing the global habits towards a sustainable choice, such as buying glass packaging or drinking public supply water, may be useful for the reduction of marine plastic pollution.
Consumers should be better informed about drinking water in order to make the right and informed choice between tap and bottled water. Information conveyed to citizens about the good quality of water supplied by public network should be combined with information about environmental impacts of plastic packaging especially in areas where plastic recycling is low. Providing the right information is a good strategy to induce people to adopt conscious, conscientious, and eco-friendly habits [46].
Actually, a negative impact on human health caused by the overuse of plastics bottles has been demonstrated [52][53][54]. Therefore, the awareness of the impacts produced by plastic, at human and environmental level, should bring people to adopt lifestyle choices in line with circular economy, limiting single-use plastic and promoting action to reduce, reuse, and lastly recycle the packaging.
These recommendations are included in the European Directive 2018/851 [55]. It indicates a waste management, based on an operational hierarchy, which gives top priority to prevention with respect to wastes disposal, by including all those processes aimed to reduce the amount of waste production, negative pressures on human health and the environment, and lastly toxic chemical compounds in products. In this perspective, efforts should be focused on promoting virtuous behaviors and increasing responsibility, encouraging the use of alternative supplies as well as the reusability and recyclability of packaging, rather than their production from raw material. Moreover, in order to induce a shift towards tap water, the EU commissions proposed: to improve access to water, upgrade drinking water standards, and increase the transparency of benefits of tap water [48].

Conclusions
Our results highlighted that: • the consumption of PET bottled water in Salento was very high, much higher than the Italian and European average; this situation leads to concern both for public health and the environment; • the perception of poor quality of tap water appeared to be decisive in the choice of consumers regarding the type of drinking water; • the younger age group consumed more tap water than the adult age groups; • in the area of the main town of the province (Lecce), a city with about 100,000 inhabitants, people consumed less tap water than in the smaller towns; • the cultural level of citizens did not seem to affect their choice.
These results lead us to affirm that effective communication strategies must be developed in order to promote the consumption of tap water and implement good practice of circular economy. These strategies must take into account the age of the population less sensitive to the problem, the perception regarding the quality of tap water, and the different social contexts to which they are addressed (i.e., population living in large cities or small municipalities), ensuring at the same time the best quality and safety of water supplied through public aqueduct.