Abstract. Water resources in Poland continue to be under stress despite systematic efforts to safeguard ground and surface water quality and quantity. Groundwater protection from nitrate pollution of human origin requires the development of sewerage systems. Such investments are often financed from public funds that must be formally appraised. The appraisal should be done by a comparison of benefits and costs of investment measures – not only financial but also environmental and social. A significant challenge is the monetization of the effects on the environment. In this paper we use non-market valuation to examine residents' preferences and estimate their willingness to pay for improving drinking water quality. This paper also contributes to the narrow literature on valuation of benefits of measures for groundwater quality improvement by presenting an application of the choice experiment method in the Czestochowa Region of Poland. To the best of our knowledge this is the first study estimating the value of benefits of the groundwater quality improvement in Poland.