Sewage disposal companies are faced with many different demands nowadays which oblige them to make more efficient and effective use of their financial resources. For site definition purposes, a quantitative assessment of performance and hence comparison with other companies is difficult because of inherent features of the system: capital costs are very high and determined in large measure by the cleaning process which is needed; the customers have no freedom of choice and few quality criteria for sewage disposal; also, great freedom of action etc. exists in respect of maintenance of the plant value. On the other hand, self-assessment helps a company to make a qualitative appraisal of the different demands placed on it. Both the strengths of a company and the potentials for further improvement are determined.