Audit Methodology - Chapter 1: System Components
- Description of facility and scope of study
- Elements of a water distribution system
- Basic procedures
- Additional procedures required for water audit
Description of facility and scope of study
Regardless of whether the audit is done by consultants or in-house resources, effective use of existing information ensures rapid progress in completing the task. All relevant descriptive statements, plans, and tabulations about the physical and geographical characteristics, including details of buildings, should be collected often from various sources.
If possible, a reference on the source of supply and natural quality of water should be included. Both the age of the building distribution system and of the municipal infrastructure connections need to be determined. Some summary remark on water usage might also be made at this point.
The objective of a water audit is to identify each facet of the water distribution system and thus define the system as a whole such that
- areas of the facility with hot and cold water supplies are identified
- measured and unmeasured water supplies are accounted for
- all points in the system where water can be extracted are identified
- distribution system design details are defined
Such investigation should provide enough information to set specific objectives for a water efficiency program, such as:
- a definition of the water distribution system and an outline of procedures for conducting a comprehensive inventory
- assembly of a comprehensive inventory, including descriptions, of all water use operations at the facility
- outline of procedures to account for all water used at the facility
- outline of procedures for developing a list of potential water reduction techniques that could be applied to specific operations, areas, or the facility as a whole
- outline of procedures to design and implement a water efficiency program at the facility
Elements of a water distribution system
The elements of a facility's water distribution system that are considered necessary for the system definition may be grouped in four broad categories:
Relevant information on the various categories may be obtained from plumbing plans, previous reports, publications, etc.
Site inspections and discussions with area personnel allow for a true understanding of the water-using activities at the facility.
Specific steps that may be used to define the system at the facility include
- a visual inspection of the facility
- a review of base maps of buildings(s)
- an inspection of plumbing drawings and transferral of key information to the base maps
- an extensive site investigation to verify information
During the investigation, an unbalanced water flow account might be encountered that may indicate leaks or losses. In addition, insufficient pressure or supply in system areas might indicate that pipe sizes and capacities should be examined. Sensitive operations may require the installation of flow meters to measure the delivery of desired flows in a particular locality.
Circumstances cited above may warrant the identification of detailed design components such as
- water supply pipe sizes
- joints and splits
- elbow turns
- any other component beyond standard plumbing
An area site plan is to be prepared with all of the facility's water meters shown, along with a schematic representation of the meters in use, depicting installations and buildings served. Plans of each section of the facility should show the major water distribution system elements. A description of the meters shown on the schematic drawing is required, complete with supply source, meter reading intervals, and purpose of metering.
Additional procedures required for water audit
There might be several other elements of the water distribution system at a facility (in addition to supply lines, meters, and use points) that need to be identified as part of the audit:
- Fire hoses, located throughout the facility, do not actually use water and therefore are not likely to be identified. These could be located during further site investigations.
- Water supply pipe sizes are determined by inspection (with reference to the plumbing drawings), since many of the water pipes at the facility may be exposed.
- Valves, joints, and elbow turns that are not identified could also be located by site investigation with the plumbing drawings used as reference.
For the water audit, the drawings of the water distribution system should be completed to include all of the above.
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