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Module 2 Describe the water supply system Session structure Overview System components and description Outputs Challenges Factors to consider Exercise 2

Module 2 Describe the water supply system Overview First task of WSP team Aim: To enable risks to be assessed and managed Involves field investigations and local knowledge Each system assessed on its own Involves documentation, review and update 3

Module 2 Describe the water supply system System components Catchment Treatment Distribution User Filtration Coagulation Clarification Disinfection Water supply and quality Land use Abstraction method and location Networks Service reservoirs Tankers General public Potable 4

Module 2 Describe the water supply system Description also involves Knowing water quality standards Assessing the likely changes to source water quality following changes in weather Describing any interconnectivity of source waters (e.g. 2 wells, 1 aquifer) Gathering information relating to water storage Identifying the operational & managerial staff involved Familiarization with existing documents relating to the supply Etc. 5

pH Turbidity UV254 pH Turbidity UV254 pH Turbidity UV254 pH Coagulant & pH adjustment RAPID MIXFLOCCULATORCLARIFICATIONFILTRATION Tropical forest River catchment 1 Run-off Raw water transfer Users City 1 Water treatment Abstraction from river Distribution system Private connection Supply flow diagram Refer to C1 description Water treatment Output 1 6

Module 2 Describe the water supply system Output 2 – understanding of current water quality Regulatory limit Nitrate concentration leaving works 7

Module 2 Describe the water supply system Outputs 3 Identification of users and uses Intended useIntended users The water supplied is intended for general consumption by ingestion. The water supplied is also for bathing and laundry. (Note that these activities can also result in dermal exposure and inhalation – through showering – of waterborne hazards.) Foodstuffs may be prepared from the water. The organization provides water to the general population. The intended consumers do not include those that are significantly immunocompromised or industries with special water quality needs. These groups are advised to provide additional point-of-use treatment. 8

Module 2 Describe the water supply system Challenges Out of date or no maps Unknown catchment land use Little stakeholder interaction / unknown stakeholders Unknown risks Limited staff time / resources available Out-of-date documentation 9

Module 2 Describe the water supply system Factors to consider Options = photographs, symbols, drawings Use flow direction arrows Cross-reference to other documents e.g. maps, treatment flow diagrams Continually update 10

Module 2 Describe the water supply system Exercise – create a system flow diagram In small groups Use symbols to describe a supply system known to you Describe from catchment to user Add star where information is not known Add banner to cross-reference to other documentation List the most important items to consider Plan how to obtain unknown information 25 minutes 11