national multiple family submetering and allocation billing program ...

The final project database was built by combining the individual databases from each
participating study site. Care was taken to preserve anonymity of individual respondents and
properties by not including any names or addresses. All survey responses were included in the
database. The final database was used by the project team to develop the causal water use
models.
Refining Historic Water Consumption
Before any data analysis could proceed, the gross historic billing data were refined. This
process required three steps: meter aggregation, consumption standardization, and the separation
of seasonal and non-seasonal consumption.
Meter Aggregation
The first step in refinement was meter aggregation, as there can and frequently are
multiple water billing accounts servicing one property. For all of the participating utilities, all
accounts that had the same property name and/or address were grouped together under one
property identification number, or PROPID. This facilitated the aggregation of water use from
multiple accounts serving a single property into a single annual volume.
Consumption Standardization
To facilitate data analysis, a single table in the project database was constructed that
contains the historic water consumption data for all properties identified through the postcard
survey. To this end, each individual utility’s database was queried for all water consumption
data available from 1999 to 2002. Different utilities bill in different units (ccf or kgal) and can
also have different billing periods (monthly or bimonthly). Thus, before being added to the final
table, all data were standardized to similar monthly consumption periods based on read dates and
the data were standardized to units of thousand gallons (kgal).
Separation of Seasonal and Non-Seasonal Demands
Where no separate irrigation meter was present, historic consumption data were separated
into seasonal and non-seasonal (outdoor and indoor) components using an estimation
methodology. The goal was to separate indoor water use from all other non-indoor demands
using all available information about each property. Obviously, more information was available
for properties that completed the manager survey than from those that just completed the
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