The per capita expenditure of water and sewerage administrations (WSAs) is an important indicator of their performance and characteristics. In this context, the effects of four parameters were investigated on the per capita expenditure of WSAs of thirty MMs in Türkiye. These parameters were determined as the service time, region, population size and budget of metropolitan municipalities (MMs). According to the results of the study, the WSAs with serving longer time and of high budget MMs had higher per capita expenditures than the others. Moreover, for the region parameter, it was determined that the per capita expenditure of the WSAs was the lowest in the Southeastern Anatolia Region while being the highest in the Marmara Region. A positive correlation was detected between the population size and per capita expenditures of WSAs. Moreover, it was assessed how much of the MMs budget was allocated to the budgets of WSAs for understanding differences among the regions. It was found that similar ratios, approximately 40% of the budgets of the MMs in the other regions except for those in the Black Sea and Central Anatolia Regions were allocated to the budgets of WSAs. On the other hand, a higher percentage of the budgets of Black Sea MMs was allocated to the budgets of the WSAs while allocating a lower percentage of the budgets of Central Anatolia MMs. According to the results, it was proposed that all WSAs should prepare master plans for at least 30 or 40 years to optimize their per capita expenditures and establish a balance between their capital and operating and maintenance costs.