Commercial Sizing Guide
For the Estimating of Flow Rates and Water Usage

Engineering Reference of Flow

You will find a listing of various water using fixtures and how to estimate the probable demand in residential properties, office buildings, schools, motels and hotels, shopping centers, and many other customers. In order to properly select water conditioning equipment, it is essential to determine flow demands. The recording of actual installations by the use of special meters and recording charts enables us to use the information as an excellent reference tool.*

The following graphs and data are the result of such research conducted by the AWWA.

• Hotels and Motels
  Hotels and motels are subject to wide fluctuations in water use, with peak periods of short duration. The example of a 216 room hotel had a maximum demand of 150 GPM, or 0.7 GPM/unit, which occurred at one time during the 24 hour period. The graph below represents the result of a recorded survey on a Texas hotel.

  

• Schools
  Flush valves with high flow requirements are normally used for sanitary purposes, and schools usually operate with uniform recess periods, both of which produce extreme water-flow-rate demands. Test results from a South Texas modern high school with 1390 students demonstrated the need to properly size equipment for these types of applications. In this particular application flows of 150 GPM were common, with peak demands reaching 210 GPM on many occasions.
• Apartments
  Apartments, like hotels have wide variations in flow rates as shown below. The survey conducted illustrates the flows throughout a one week period.

  *Utility engineers have used a wide variety of methods to estimate a customers peak water demand, which range from a rule of thumb procedure to detailed criteria. The information here has been taken from field experiments, utility surveys, technical publications, and hydraulic design methods, all of which are assembled into a condensed explanation of customer demand and how to determine the maximum flows that can be expected.

The majority of the contents within this publication have been extracted from the American Water Works Association (AWWA) Manual M-22. In determining demands of commercial applications, professional engineering information and on site experience are essential in final analysis of determining probable flows. The AWWA manual lends this design experience to efficiently calculate flow demands in commercial applications.