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

3. 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

4. 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

5. 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.

6. Abstraction from river
Supply flow diagram
Tropical forest
River catchment 1
Run-off
Raw water transfer
Users
City 1
Water treatment
Abstraction from river
Distribution system
Private connection pH
Turbidity
UV254
Coagulant
& pH adjustment
RAPID MIX
FLOCCULATOR
CLARIFICATION
FILTRATION
Output 1
Water treatment
Flow diagrams/schematics need to be sufficiently detailed to identify hazards and assess the risks. It is often useful to develop an overall map of the system (as shown above), along with detailed maps/schematics for the different water supply components.
Diagram credit: Simon Parsson, Cranfield University
Refer to C1 description

7. Module 2 Describe the water supply system
Output 2 – understanding of current water quality
Regulatory limit
Nitrate concentration leaving works
Picture credit: Simon Parsson, Cranfield University

8. Module 2 Describe the water supply system
Outputs 3 Identification of users and uses
Intended use
Intended 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.

9. 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

10. 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

11. 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