Summary:

Correct functioning of sewage disposal and treatment systems depends prevalently on the proper design, construction and subsequent proper operation. In designing sewer systems the most important parameter affecting determination of pipe diameters is a reliable sewage volume, frequently determined per 1 inhabitant as a unit sewage outflow in dm³∙M^-1∙d^-1. The investigations were conducted to determine unit sewage outflows from rural sewerage system in Koszyce per year, with respect to individual months and days of the week in 2002-2005. The volume of sewage flowing out of sanitary sewer system in Koszyce was determined on the basis of measurement conducted on the supply canal to the sewage treatment plant in Włostowice. Koszyce municipality is situated in the malopolskie province, proszowicki poviat. Currently the sewer system in the municipality area is utilised by 1673 inhabitants. Sewage is discharged by 280 households. Mean daily sewage outflows (at the rainless weather) during the period of research fluctuated between 58.7 in 2005 and 75.1 dm³∙M^-1∙d^-1 in 2003. During the whole period of investigations mean unit outflow was 67.1 dm³∙M^-1∙d^-1, with standard deviation 11.5 dm³∙M^-1∙d^-1. and irregularity coefficient 1.34. The values of average unit sewage outflows in individual years corresponded to unit values of water consumption in 7 investigated households in Włostowice in 2002-2003. The highest unit sewage outflows in Koszyce occurred in the winter months, while the lowest in the summer months. An analogous tendency occurred for water consumption. Sewage effluents, lower in the summer period, were connected with the use of considerable amounts of running water for additional purposes, such as crop watering, washing of vehicles and keeping farm animals. The analysis of sewage outflow per week revealed that the lowest unit sewage outflows from the sewer system in Koszyce occurred on Fridays (66.0 dm³∙M^-1∙d^-1) and Sundays, whereas the highest were registered on Saturdays (73.2 dm³∙M^-1∙d^-1). It is the scheme confirming the most frequent weekly water consumption distribution. Investigations of unit sewage outflows from rural sewer system in Koszyce corroborated the thesis on a decrease in the actually produced sewage volume in relation to the Guidelines issued in 1978. Unitary sewage outflow did not exceed 100 dm³∙M^-1∙d^-1 during the whole period of investigations.