To achieve their sustainability targets, industries need to deploy assessment methods to evaluate their water use in terms of water availability and pollution of local water resources (Willet et al 2019). The interconnections between sustainability, industrial water use, and assessment methods is captured by the concept of ‘Sustainable Systems Indicators’ (SSIs) proposed by Veleva et al. (2001). The OECD classification of assessment methods (OECD, 2009) which is the most suitable since it is the closest to practice within industry, is comprised of six categories: 1) Key Performance Indicators, 2) Socially Responsible Investment Indices, 3) Composite Indices, 4) Material and Energy Flow Analysis, 5) Environmental Accounting, 6) Life Cycle Analysis. WF assessment falls into the category of Material and Energy Flow Analysis method, which has the largest percentage of use of SSI at 42% compared to the other methods. The underlying concepts of mass/energy balancing are suitable for SSIs because they can be used over any scale and can therefore be applied outside the immediate boundaries of the industrial system (Willet et al 2019).
Initially, WF was focused on crops and national consumption (Hoekstra and Hung 2002). Hoekstra and Chapagain (2007, 2008) improved the national WF accounts by considering all forms of consumption and trade, including animal and industrial products and municipal water uses. After 2008, the scope broadened, whereby also increasing attention on manufacturing within certain geographic areas expanded the WFs in the context of the limited water availability per area (Hoekstra 2017).
Water footprint in the context of sustainability assessment has been introduced through six widely recognised methods i.e., i) water footprint by Hoekstra (Chapagain & Hoekstra 2004); ii) ISO 14046 water footprint following an impact assessment approach with water input output analysis; iii) stress weighted approach by Brent (Brent 2004) comparing the use of different types of resources through a distance-to-target normalization, iv) swiss ecological scarcity method (Frischknecht et al. 2009) proposing a set of ‘eco-factors’ to assess freshwater resource use; v) life cycle inventory by Owens (Owens 2001) suggesting a set of indicators among different types of freshwater uses in terms of water quantity and quality ; vi) impact assessment of freshwater consumption according to Pfister et al. (2009) assessing freshwater consumption on midpoint and endpoint level, focusing only on freshwater consumption. All methods are based on the same water type concept proposed by Hoekstra et al (2009), which follows a volumetric approach (i.e., assessment of the volume of water associated with a particular production activity). This methodology could provide a baseline for inventorying water use data, however further differentiation is needed for impact assessment, customized to the characteristics and needs of the study area and the system boundaries (Sala et al. 2013).
Water footprint (WF), according to Hoektra et al (2009), is a multidimensional indicator of volumetric water use and pollution, measuring the amount of water used to produce goods and services. It can refer to a process, a product, an entire company, a sector, a community, even a nation. The WF of an industry is defined as the total volume of fresh water used, directly and indirectly, to produce its products and services. It consists of Operational WF, focusing on the industrial processes i.e. manufacturing & packaging, and of Supply Chain WF, focusing on the raw materials used in the production line (Gerbens-Leenes and Hoekstra 2008). Both direct and indirect water use are included in the indicator, representing water consumption and pollution throughout the full production cycle from the supply chain to the end-user (Hoekstra et al. 2009).
Despite the wide importance of WF as a water sustainability indicator in industry, very limited studies have been conducted to assess the indicator for industrial plants. The majority of scientific studies, corporate and international reports account and report water consumption and wastewater generation data and volumes. Therefore, they are mainly focused on water consumption and wastewater production data and rates in different industrial branches as well as some WF assessment studies available in international literature.
Water consumption for the manufacturing and power generation industries constitutes over 70% of total industrial water consumption in most European countries, mainly consumed for cooling purposes. Power generation industry has the largest water consumption ranging from 52.2% (Latvia) to 99.4% (Cyprus) of total industrial water needs. In most countries, petrochemical and chemical industries consume the largest amounts of water compared to other manufacturing industries and the average consumption ranges from 0.2 m3/inhabitant in Cyprus and Malta to 205.8 m3/inhabitant in Finland (Eurostat 2020).
Currently, water demand in manufacturing industries accounts for 22% of global freshwater withdrawal, and in some countries industrial water consumption exceeds water needs in agriculture (Sachidananda et al. 2020). Typical water consumption per inhabitant in EU countries for food & beverage industry ranges from 1.7 m3/inhabitant in to 15.8 m3/inhabitant, for textiles industry from 1.7 m3/inhabitant to 15.8 m3/inhabitant, for pulp and paper industry from 1.7 m3/inhabitant to 15.8 m3/inhabitant and for refined petroleum products, chemicals and chemical products ranges from 0.2 m3/inhabitant to 205.8 m3/inhabitant (Eurostat 2020).
Focusing on breweries, cement production and cosmetics units, which are characterized as water intense branches within the manufacturing industries, very limited studies on WF are available in literature, probably due to the restrained availability of data from industrial units (Hosseinian and Nezamoleslami 2018; Gerbens-Leenes et al. 2018). Nevertheless, many studies report water consumption and wastewater generation data for the selected branches, based on which a preliminary evaluation of water use can be performed.
Data on water consumption in the brewing processes retrieved from literature are reported in Table 1. Data for craft beer (Morgan et al. 2021) are not included, due to the brewery capacity, the non-inclusion of packaging process and the non-existence of filtration process. Beer is expressed to hL, a common measurement unit in the branch. Breweries consume large amount of water in their production processes, so proper monitoring and identification of water intense processes are crucial for the implementation of strategic actions for water savings. World Bank (2007) and the Government of Canada (Environment Canada 1997) propose that a water consumption rate of 4 to 6 hL water / hL beer is optimal for sustainable water consumption in breweries.
Table 1
Water consumption rates in beer production (normalized to hL water / hL beer, so as to be comparable)
Water Consumption Rates (hL water / hL beer) | Literature Source |
4–10 | Fillaudeau, Blanpain-Avet and Daufin 2005 |
4–10 | Hannover 2002 |
4–11 | Perry and De Villiers 2003 |
4.90–12.64 | Kunze 2004 |
6 | Taylor 2018 |
4.73 | van der Merwe and Friend 2002 |
5–6 | Perry and De Villiers 2003 |
5.5–8.8 | Ramukhwatho et al. 2016 |
Concerning wastewater generation from breweries, limited data are available and are presented in Table 2.
Table 2
Wastewater consumption rates in beer production
Wastewater Production Rates (hL wastewater / hL beer) | Literature Source |
1.3–1.8 | Olajire 2012 |
1.9–11.50 | Reed 2006 |
5.5–9.7 | Briggs et al. 2004 |
For cement production industry, two WF assessment studies are available, estimating both direct (production processes) and virtual (energy consumption and transportation) WF. According to Hosseinian and Nezamoleslami (2018) the direct operational WF was estimated at 0.17 L / kg cement and the virtual WF at 1.95 L / kg cement for a plant in Iran. Gerbens-Leenes et al. (2018) estimated the WF of cement using data from the Ecoinvent database, resulting to 0.68 L / kg cement for the total operational blue WF of Portland cement, higher than both the above value and the average of Table 3, and to 210 L / kg cement for grey WF, counting for mercury as a primary pollutant. Finally, in many corporate sustainability reports and research articles, water consumption rates reported for cement manufacturing plants range from 0.14 to 1.28 L / kg cement (Table 3).
Table 3
Water consumption rates in cement production (normalized to L / kg cement)
Water Consumption Rates (L water / kg cement) | Literature Source |
0.229, 0.232 | Cemex (2019, 2018) |
0.17, 0.14, 0.24, 0.260 | Lafarge (2019, 2018, 2012) |
0.267 | Heidelberg Cement (2019). |
0.36 | China Resources Cement (2019) |
0.264, 0.274, 0.413, 0.408 | Cement Argos (2019, 2018, 2017, 2016) |
0.185, 0.281, 0.260, 0.3, 0.360 | Holcim (2014, 2013, 2012, 2010) |
0.521, 1.028, 0.537 | Marceau et al. (2006) |
0.195 | Hydraulic Binder Industries Union (2002). |
Cosmetics can be divided into two main categories; synthetic cosmetics, in which ingredients have been developed in a lab, and natural cosmetics, which contain at least 95% of natural ingredients. Water is the main ingredient of most cosmetics products and usually water is the main ingredient, accounting for more than 2/3 of the volume of a formula (Cosmetics Business 2019).
Cosmetics industries are already investing on water sustainability in the manufacturing and end-use phases of their products. L'Oréal achieved 60% reduction of water consumption in 2020, compared to 2005, and enabled consumers to reduce water consumption by 25% when using the product, compared to 2016, through changing the formulas to optimize water consumption and recycling and reuse application within the manufacturing sites (L'Oréal 2019, 2020). Also, Unilever reduced the WF of its products by 47% the last 10 years, investing also in new hair products that could save 460 l of water per bottle of conditioner (Unilever 2020).
Concerning natural cosmetics, only one WF assessment study is available, estimating both direct WF from the production processes and virtual WF from energy consumption and transportation (Francke and Castro 2013). Blue, Green and Grey WF were assessed for the whole product cycle, from the supply chain to the end user, for a 450g Macadamia soap, with data from Ecoinvent being combined with real water consumption measurements. Many studies have been conducted showcasing sustainability practices, nevertheless neither water consumption and wastewater generation data nor metrics for natural cosmetics plants are available, only tendencies in water use between the years (Bom et al. 2019; Kolling et al. 2022; Secchi et al. 2016; Aguiar et al. 2022).