The feasibilityty of using noninvasive flowmeters for determining water use was investigated by attempting, and at some sites repeating, instantaneous pipe-flow measurements at 45 water-withdrawal sites by use of four portable noninvasive pipe flowmeters. The flowmeters measure flow in pipes; this flow is related to water use. Because actual water use can differ from the total flow in the pipe, water use is not, in itself, measured by the flowmeters.

The transit-time flowmeter successfully measured flow on 81 of 88 measurement attempts. The time-of-flight flowmeter successfully measured flow on 85 of 93 measurement attempts. One reflective-doppler flowmeter successfully measured flow on 71 of 75 measurement attempts. Another type of reflective-doppler flowmeter, which required air bubbles or paniculate matter in the flow, successfully measured flow on 19 of 92 measurement attempts. Flows at most water-withdrawal sites selected for this study did not include paniculate matter.

At 10 site visits where inline flowmeter measurements were available for comparison and where three of the four selected portable flowmeters were successful, the transit-time flowmeter measurements had a mean log-percent difference from the inline measurements of 2.8 and a standard deviation of 3.7. The time-of-flight flowmeter measurements had a mean log-percent difference of 7.5 and a standard deviation of 7.6. The reflective-doppler flowmeter measurements had a mean log-percent difference of -14 and a standard deviation of 18.

The feasibility of using time totalizers for determining water use was investigated by observing seven vibration time totalizers (VTT's) mounted at five sites. None of the units exhibited adverse effects from the heat, precipitation, or humidity associated with Indiana summers. One VTT was mounted at a public water-supply site where inductive time-totalizer measurements were available for comparison. The VTT agreed within 8 hours of the inductive time totalizer after 2,340 hours of pump operation. There were no mechanical prpblems with the VTT units used in this study.