The article has analytical and conceptual character. It contains a detailed analysis of the scope of cadastral information on waters based on actual data from the regional databases, which are established in four logistically major cities in Poland: Warsaw, Krakow, Wroclaw and Szczecin. The authors examine the contents of water cadastre databases in Poland and possibilities of using them in building the 3D cadastre. The concept of using water cadastre as a subsystem of the 3D cadastre presented in the work was carried out using graphical methods of the object-oriented analysis. The authors present a Real Estate Cadastre (REC) model based on synchronisation of the Land Register databases with the water cadastre databases carried out in District Water Management Boards. Modernisation and thematic expansion of Land Register databases, which act in Poland as cadastre, consistent with the presented REC model is a chance to improve the real estate market in Poland.