Overview
How do we, as operators, control the distribution of water? How do we know if our water distribution system is working properly? What factors impact on the quality of our water supplies? How do we report on our work?
Do a workplace project, or use this case study to respond to the impacts of bushfires in a catchment. The learning tasks take you through monitoring sites, water quality testing, using a SCADA system and discussing relevant issues.
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Water distribution systems include all the physical things that are required to get the water from the source to the customers. This includes the water itself in reservoirs, lakes, rivers, dams and bores, and the hardware - pipes, pumps, valves and fittings. This is called a ‘reticulation system’.
Water quality needs to be monitored to maintain community health. Operators regularly monitor water quality to ensure that it meets the standards set out in the Australian Drinking Water Guidelines.
Many factors can affect water quality. Some are predictable, such as the source of the water and its location. Other factors are less predictable, such as bushfires, weather conditions and algal bloom infestations. Each of these factors affects the kinds of tests that are carried out.
Some tests are widely used and likely to take place in every water authority. These include tests for turbidity, pH, E-coli and electrical conductivity. Other tests are more specific to particular locations or incidents, such as tests for iron and manganese content.
Monitoring and operation of water distribution systems has traditionally been carried out manually through field work and at the treatment plant. These days, much of the monitoring and operation is carried out by Supervisory Control and Data Acquisition systems – known as SCADA.
Controlling the water distribution system is usually carried out by adjusting flows and volumes within the system. Adjustments to valves are made either manually or by using SCADA, and are made depending on water usage.
Water distribution systems are usually designed to allow water to be diverted so that repairs can be carried out or for flows in the system to be reversed. Storage levels are monitored and water is often pumped from one storage to another.
The water pressure in household taps comes from the storage being higher in the catchment. Operators monitor pressure at various points in the distribution system. Customers report faults such as loss of pressure or dirty water to Water Authority staff.
Information is collected from the water distribution system in a systematic way. This might take the form of pump hours, levels in tanks, or flow rates and pressures at various points. Data concerning water quality is also collected as a result of testing. All of this information is compiled into reports that are collected and filed by the Water Authority as required by relevant legislation.
Information is also collected concerning condition of various components of the reticulation scheme. This may take the form of recording the hours pumps have run, or a systematic survey of valve condition. Information collected in this way may form the basis for maintenance schedules for various components. Any faults found in components as a result of surveys are reported and will result in maintenance or replacement of the component.
