The drinking water quality of Zalaegerszeg and certain settlements supplied from the eastern water base (Bocfölde, Sárhida, Zalaszentiván, Zalaszentlőrinc, Alibánfa) does not comply with the ammonium content. The water quality parameters set out in Government Decree No 25 October 2012. On the basis of the documents submitted and the test reports, 22 wells provide water supply to the settlements, 16 of which have an ammonium content exceeding the relevant parametric value, and iron and/or manganese content in the wells is contested. The water of the wells is treated in Zalaegerszeg and Zalaszentiván municipal waterworks with outdated iron and manganese decontamination technology, which is not designed for de-ammonium extraction, the operation of which is unsafe and sometimes ammonium and nitrite appear on the network. In case of inadequate ammonium removal, spontaneous nitrification on the network may occur in water with high ammonium content, posing a risk to public health. The main technical elements of the project are: technological development, transfer of Zalaszentiván system to Zalaegerszeg network, development of drinking water transmission line, Egerszeghegy basin, exchange of raw water pipelines. It is also necessary to carry out the reconstruction and development of outdated network elements, but the costs of reconstructing the drinking water network do not exceed 20 % of the total eligible costs of the project.