A method is presented with which the mechanical cleaning effect of flushing disinfectors can be estimated independently of the thermal disinfecting effect of the hot flushing water. This makes it possible to specify the demands to be placed on the disinfecting effect of flushing with water of 85°C or more.

Bacillus stearothermophilus spores suspended in faeces were used as indicators because of their non-sensitivity to the hot-water temperature. Their elimination by flushing could thus be attributed to the mechanical effect of the water and not to the disinfecting effect of the temperature. A simple bacteriological technique was used, and the elimination factor (EF) was calculated as the ratio of the number of micro-organisms in the contamination before and after flushing. By using flushing water below 50°C for 130 s the EF on a bedpan was about 104–106. The effect of flushing with water of the same temperature for only half that time was somewhat weaker and when the temperature was raised to 85 °C after half the flushing time the effect was somewhat stronger.

It can be presumed that the conventional disinfecting phase with hot (85 °C) water for about 45 s in the commonly used flushing units could be substantially shortened and the costs of their use thereby reduced.