ABSTRACT
Bajer 2007, Bajer 2013, Pietrucha-Urbanik 2014, Rende 2007, Studziński 2014) but not in every water supply system there is a tank. In such case, same as when there is one tank in the water supply network, we deal with a lack of water volume diversification (Rak 2015, Dąbek 2015). Diversity is also topic of many other research in finance, sports, biology, chemistry, social science (Ball & Crawford 2006, Blanch et al. 2001, Corradini & De Propris 2015, Humphrey et al. 2015, Hong & Herk 1996, Kashcheeva & Tsui 2015, Maj 2015, Mariano et al. 2016, Sterkowicz-Przybycien 2010).
