The drinking water network system of Fővárosi Vízművek Zrt. is characterised by a large network, low flow rates, suboptimal zone designs and the resulting high residence times. The well capacities of Budapest Waterworks are no longer sufficient to ensure consumption needs in the case of extremely low water levels. The increasing trend in the frequency and duration of small water periods also entails quality risks for drinking water. An additional water quality risk is associated with more than 4600 lead input lines on the distribution network. In order to maintain water quality at an appropriate level, the project includes the following elements: — improved transformation and modification of the network from a hydraulic and water quality point of view (rationalisation of large-diameter lines, rationalisation of distribution network) — replacement of lead-based access lines — increasing the filter surface of wells and developing wells.