The water supply for population existentially – economic needs use surface water or underground water. As a source, small water supply stations mostly use the underground water, with increased level of iron and manganese. Treatment of such water can be done by conventional methods based on filtration through a bed of gravel or by modern methods, eg. membrane separation (microfiltration, nanofiltration, ultrafiltration, reverse osmosis). Each technology generates specific costs, and therefore a comparative analysis of the costs of classic and membrane technologies has been made for water treatment station with an average efficiency 571 m3 • d–1. Investment and operational costs for selected devices were calculated (assuming the operation time of 30 years) – it has been found that these are comparable for both technologies. The difference amounts to 7.5% and 3% in favor of the classic technology. In the case of construction of a new station classic technology cost is higher than membranes because it requires new building. It is expected that with the increasing popularity of membrane technologies the costs of their use will gradually decrease.