## 2 The Literature Review  
The results of the tests of selected indicators of specific water consumption \(W_{w}\) are given in Table 1. \begin{table}
\begin{tabular}{l c c c} \hline \hline  & \multicolumn{3}{c}{**Unit water Consumption Indices**} \\ \cline{2-4}
**Production, Water Intake Directions** & \multicolumn{3}{c}{**(m\({}^{3}\)/mg of Product)**} & **Source** \\ \cline{2-4}  & **Index Range \({}^{*}\)** & **Numerical Value** & \\ \hline \multicolumn{4}{l}{Tomato juice thickening in rotary evaporators} \\ \multicolumn{4}{l}{-} & AC 100 (35.2 kg/(m\({}^{2}\)-h)) & \(A\) & 101.1 & [7] \\ \multicolumn{4}{l}{-} & AC 200 (40.0 kg/(m\({}^{2}\)-h)) & \(A\) & 85.3 & \\ \multicolumn{4}{l}{-} & PR 16 (31.8 kg/(m\({}^{2}\)-h)) & & \\ \hline \multicolumn{4}{l}{Fruit washing} \\ \multicolumn{4}{l}{Vegetable washing} \\ \multicolumn{4}{l}{Vegetable peeling} \\ \multicolumn{4}{l}{Vegetable peeling} \\ \multicolumn{4}{l}{Blanching} \\ \multicolumn{4}{l}{Refrigerating} \\ \multicolumn{4}{l}{Marmalades, preserves} \\ \multicolumn{4}{l}{Fruit juices} \\ \multicolumn{4}{l}{Retort fruit preserves} \\ \multicolumn{4}{l}{Retort vegetable preserves} \\ \multicolumn{4}{l}{Salad preserves} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Water consumption index per product unit in fruit and vegetable industry plants. The presented indices are diversified, which results from both the differences in the technical equipment of the plants and the diversity of methods of determination of the said indices [20]. The indices may be data intended for the design of new plants or estimations of the future demand for water. The plant unit water consumption indices \(W_{w}\) contribute the most information. Admittedly, the literature partially specifies the variability ranges of plant unit water consumption indices but does not list many factors that could affect their numerical values. Method basics with this scope can be found in publications [21; 22]. Publication [22] presents the general characteristics of sixteen production plants. Daily water consumption in the summer-autumn period ranged from 55.2 to 5431.8 m\({}^{3}\). Units of water consumption in the analyzed plants differed more than sevenfold. The following questions can be posed in this context:  
* How can the variability of water consumption by plants in this industry be explained? * How can the optimum water consumption in a given plant be determined? In order to respond to the first question, the determining factors and strength of their impact on water consumption \(A_{w}\) and, subsequently, on the values of unit consumption indices \(W_{w}\), must be determined. The authors of publication [22] presented exemplary groups of factors (independent variables) that affect the consumption of water, covering the scope of the plant index, Table 2. \begin{table}
\begin{tabular}{c c c c} \hline \hline Group of Factors & Meaning, Physical Sense & Applied Markings \\ \hline I & Value generally characterizing the plant & \(V_{1}\), \\ \hline II & Elements of the structure of installed power of the plants & \(P_{1}\), \\ \hline III & Structure of daily production & \(Z_{1},Z_{2},Z_{3}\) \\ \hline IV & Level of technical and technological equipment and & \(K_{2}\) \\  & production organization & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Factors affecting water consumption in production plants.