Water meters for all customers are sized by PAWSD based upon a fixture count of the building. Although there may be a tendency to choose a meter that is larger than needed in order to conservatively estimate and accomodate water demand, accurate meter sizing is important for a host of reasons:
Properly sized meters have a lower failure rate.
Smaller meters require less maintenance than larger meters, in turn reducing the cost of water shut-offs and repair.
Smaller meters have a lower Capital Investment/Water Resource Fee and basic service charge.
Smaller meters encourage water conserving fixtures and practices.
The American Water Works Association (AWWA) recommends defining water demand using a flow recorder or manual fixture value calculations. Fixture values are provided by the Uniform Plumbing Code. The PAWSD Board of Directors has adopted the fixture count methodology. Fixture counts and Equivalent Units are determined by the following steps:
What fixtures are present?
What are their values given by the Uniform Plumbing Code (UPC) or the International Plumbing Code (IPC)? For example, a bathroom sink has a count of 1, and a dishwasher has a count of 4. Values vary depending upon the intended use of the fixture: will it be used generally throughout the day, or used very heavily for a short period of time, such as a toilet in a theater during intermission?
Are there fixtures not included in the first UPC table? If so, use the gallons per minute demand of each of these fixtures to assign it a fixture count. This can be done using a second UPC table.
The values of all the fixtures are totaled and the meter size that is appropriate for that total fixture count is determined using the AWWA meter design criteria and Uniform Plumbing Code. Once the meter size is known, equivalent units are assigned which mirror the hydraulic ratio of that particular meter size to the base line 1” meter size.
The result of these steps is an industry standard-based methodology for calculating Equivalent Units that reflects true demand.
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