Rehabilitating water treatment works after an emergency
Technical note 6 on drinking-water, sanitation and hygiene in emergencies
Step 1: Assess the situation
In urban areas, the population may be entirely reliant on the public water supply system for their drinking-water. Modern water treatment works rely on the inputs of skilled operators as well as supplies of chemicals, electricity and machinery. A disaster can cause extensive damage to the works leading to a reduced or even a total loss of output. This technical note identifies the first steps to take towards rehabilitating a water treatment works after an emergency. Details of the rehabilitation of smaller systems are given in Technical Note 4.
Steps for rehabilitation
In an emergency, the primary goal of rehabilitating a water treatment works is to maximize the quantity of water produced. This is followed by the gradual, step-by-step improvement in water quality. Most water treatment works are connected to a piped distribution system. This, too, needs to be rehabilitated if the treated water is to reach the consumer. Details of the rehabilitation of distribution systems are given in Technical Note 4.
Assess the situation
Identify key workers
Identify local water treatment operators who understand the system. They can provide knowledge of the works and the sources of supply. Often, however, operators do not fully understand the treatment process, so try to identify professional engineers, scientists and managers who do. Note that you may have to pay operators and managers if the emergency has interrupted their salary payments.
Understand the process
In order to rehabilitate the water treatment plant it is important to understand how it works. Individual plants will vary in design, but most are based on a sequence of processes that fit together to improve the quality of water in incremental steps. Figure 6.3 shows the principal processes. Not all processes shown will operate in every case. In some cases the order in which they take place will differ.
Assess the condition of the plant
The condition of each plant component will need to be assessed. Identify which components are working, which could be repaired and which will have to be replaced. Repair and renovation is generally quicker than replacement, particularly if skilled workers are available locally. Be aware that damaged components may not necessarily be related to the disaster. Chronic underfunding and lack of skilled workers is a common problem in the water industry, so treatment plants frequently do not function correctly, not only during emergencies.