Systematic oversizing of service lines and water meters

Abstract

Sizing service lines and water meters for buildings is a common exercise with important implications for utilities and consumers. Selecting the diameter of a service line requires designers to balance economics and performance. Smalldiameter pipes may minimize cost but impair service with high head loss; larger pipes may ensure adequate pressure but increase the cost of the premise plumbing system. The water meter must also be sized to perform reliably and accurately while measuring both high and low flows. In this investigation, flow data from 43 buildings fitted with water-conserving fixtures were collected at 10-s logging intervals for 2 weeks. It was found that 37 of the 43 sites would likely have benefited from a smaller water meter. Of the 37 sites, 29 could likely have also been fitted with a smaller service line and not violated a 10-ft/s water-velocity limit that some building codes impose. K E Y W O R D Splumbing design, premise plumbing, water meter sizing

Comparing Actual and Designed Water Demand in Australian Multilevel Residential Buildings

“…Most plumbing standards used to predict peak flow rates for plumbing systems are built on the research conducted by Hunter (1940). Hunter employed a probabilistic approach, recognizing the use for plumbing fixtures followed a binomial distribution, where a fixture is either in use (busy) or off (idle) (Douglas et al 2019). Through monitoring conducted for two hotel buildings during congested usage periods, the duration of use (t) and time between successive uses (T) was observed to determine a specific fixture's probability of use (p).…”

“…It is now recognized by the plumbing industry that the approach used in most international plumbing codes to predict peak flow rates leads to significant overestimation (Bleys et al 2012;Douglas et al 2019;Jack et al 2017;Mayer et al 2019;Tindall and Pendle 2015). A key reason is the widespread adoption of water-efficient fixtures (Hobbs et al 2019).…”

“…Considering that some specific plumbing hardware and fixtures are known to have optimal velocity ranges for effective operations, the overestimation of peak flow and the peak-flowdriven design philosophy implies that some hydraulic components used to control and regulate plumbing systems may rarely operate within the manufacturer-specified hydraulic range. Douglas et al (2019) indicate an upper-limit design philosophy as a potential contributor to the oversizing of water service lines and water meters that results in poor performance and reduced accuracy. In addition, this design practice may be a significant contributor to water quality issues and premature failures (Farooqi et al 2009) seen in many plumbing systems.…”

“…A 10-s logging interval was selected to permit direct comparison between previous studies that used the same logging frequencies (Douglas et al 2019;Mayer et al 2019).…”

“…Typically, peak flow rates are estimated through the application of plumbing standards. However, several recent studies have demonstrated that methodology stipulated within international plumbing codes can significantly overestimate the actual peak hydraulic demand in residential apartments and mixed-use buildings (Bleys et al 2012;Douglas et al 2019;Jack et al 2017;Mayer et al 2019;Tindall and Pendle 2015). Overestimation of peak demands leads to oversized plumbing systems that drive up construction costs, elevate energy consumption, degrade water quality, and can increase the risk of premature failure of plumbing hardware and fixtures (Douglas et al 2019).…”