operation costs, i. e. the human resources required for operating the system as a whole;
maintenance costs, determined by the number of control units and their individual costs;
depreciation costs, which reflect the age, wear and tear of the infrastructure.
Improving service levels will automatically entail increase in management ability or upgrading of the infrastructure or both. So an acceptable trade-off should be found between investments and management ability to achieve a certain service level, assuming service level to be one of the management goals.
Clearly defined service level agreements and effective accountability systems are the basic requirements for a reliable and effective service. In this way a direct relationship is established between demand, level and cost of service on the one hand, and payment for services on the other. To minimize cost variations, hence the service charges, proper planning of service cost is essential. In this context, a reliable asset management plan is an indispensable tool.
5. Challenges for the future
At the beginning of the twenty-first century, conjunctive use of surface and groundwater is coming under pressure on a number of fronts. The expected demand for water exceeds available resources, plans fall short of targets, population is increasing, though growth rates are slowing down, and economic crises coupled with environmental concerns further complicate and exacerbate efforts under way to tackle these problems.