Presentations & Publications

Derivation and Use of the Pump Energy Intensity Equation for Water System Energy Analysis

Rob Sowby and Kai Krieger

Energy intensity—an expression normalizing pump energy use by water volume—is becoming a more commonly used key performance indicator as water utilities seek to analyze and optimize their energy use. Its theoretical basis, however, has not been well documented. Beginning with Newton’s second law, we derive the pump power equation and the pump energy intensity equation, provide specific values for engineering reference, and discuss applications. In a perfectly efficient system pumping water, the minimum energy intensity is 0.00272 kWh/m3 per meter of head or 3.14 kWh/Mgal per foot of head.

Practical Experience with the Modified Philip–Dunne Infiltrometer Test

June 2023 | Rob Sowby, Dan Jones, and Kayson Shurtz

The modified Philip–Dunne (MPD) infiltrometer test has been promoted as an efficient option for field measurement if hydraulic conductivity, particularly in rain gardens and other green stormwater infrastructure. However, the literature misses some details on its performance in practice. Based on our experiences building our own equipment, executing the test in various field conditions, and determining hydraulic conductivity for the purposes of engineering design, we describe some limitations for other users to consider and improve upon.
Journal of Sustainable Water in the Built Environment

Insights into Efficient Irrigation of Urban Landscapes: Analysis Using Remote Sensing, Parcel Data, Water Use, and Tiered Rates

2022 | Kayson M. Shurtz, Emily Dicataldo, Robert B. Sowby, and Gustavious P. Williams (BYU)

To understand how landscape irrigation can be better managed, we selected two urban irrigation systems in northern Utah, USA, and analyzed relationships among water use, irrigated area, plant health (based on the Normalized Difference Vegetation Index), and water rate structures across thousands of parcels. Our approach combined remote sensing with 4-band imagery and on-site measurements from water meters. We present five key findings that can lead to more efficient irrigation practices.


A Practical Statistical Method to Differentiate Inflow and Infiltration in Sanitary Sewer Systems

2022 | Robert B. Sowby and Daniel R. Jones

Municipal sanitary sewer systems receive unwanted inflow and infiltration (I/I) that adversely impact their sizing, economics, and operation. Here, a practical regression model of daily sewer flow is developed with discrete terms for sanitary flow, groundwater infiltration, direct inflow, and delayed inflow to help practitioners characterize I/I and improve sewer system performance.

Journal of Environmental Engineering (ASCE)

Considerations for Studying the Impacts of COVID-19 and Other Complex Hazards on Drinking Water Systems

2021 | Robert B. Sowby and Nathan T. Lunstad

The COVID-19 pandemic has affected public drinking water systems in unprecedented ways due to protracted disruptions in supply chains, customer demand patterns, staffing, and revenue. This paper lays out key questions for study the effects and making water systems and other infrastructure more resilient to these types of complex hazards.

Journal of Infrastructure Systems

The 3 A’s of Hydraulic Modeling

2021 | Robert B. Sowby

Hydraulic modeling is the backbone of water system engineering. Understanding “the 3 A’s of hydraulic modeling”—Accuracy, Applicability, and Accessibility—will help you get the most out this important tool.

The Flow Winter 2021, 15–17

Leading-Digit Patterns from Smart Water Meters

November 2020 | Robert B. Sowby and Daniel R. Jones

This study examines leading digits (i.e., first non-zero digits, 1–9) in hourly smart meter readings from a western U.S. water utility. The readings tend toward values that start with 1. This suggests that water use by individual customers should follow a particular pattern of leading digits and that deviation from the pattern may indicate data errors or abnormal water use.

Emergency Preparedness after COVID-19: A Review of Policy Statements in the U.S. Water Sector

May 2020 | Robert B. Sowby

Although COVID-19 has impacted water and wastewater utilities in new and profound ways, they must still provide their vital services despite the disruptions. In the midst of the crisis, several U.S. policies are reviewed here. Utilities should reflect on their COVID-19 experience, learn from it, and apply their newfound perspective to strengthen future emergency preparedness.


Utilities Policy

High-Resolution Energy Intensity Modeling to Improve Water Distribution System Performance

2020 | Robert B. Sowby and Steven J. Burian (Univ. Utah)

Water distribution systems can improve their sustainability by implementing the most energy-efficient scheme for water delivery, but this is difficult to determine for complex systems. A method proposed here combines facility-level energy intensity data with hydraulic simulations to map the flow of energy through the water distribution system and quantify the response of local energy intensities to proposed  modifications.

Journal of Sustainable Water in the Built Environment

Water Is a Finite Resource, with Hidden Energy Savings Floating Just Below the Surface

August 2019 | Matt Jensen (Cascade Energy), Rob Sowby, and Chellie Jensen (Idaho Power)

Municipal water systems are major energy users where savings float just below the surface. This paper summarizes an effective strategic energy management (SEM) approach—combining industrial energy efficiency, water resources engineering, and people-centered action—to capture those hidden energy savings.

ACEEE Summer Study on Energy Efficiency in Industry

Energy Management Program Leads to Operational Improvements

May 2019 | Robert B. Sowby, Steven C. Jones, Sam Christiansen (North Salt Lake), and Matt Jensen (Cascade Energy)

The City of North Salt Lake, Utah, reduced its water system’s energy use by 25% during a strategic energy management (SEM) program focused on no-cost opportunities. Pressures and water quality also improved as the water system staff embraced energy-efficient operations.


Discussion of “Leakage Control and Energy Recovery Using Variable Speed Pumps as Turbines”

June 2019 | Robert B. Sowby

This discussion responds to a study by others and highlights important assumptions and considerations for recovering energy in water distribution systems.

Journal of Water Resources Planning and Management (ASCE)

Data Challenges and Solutions in Energy‐for‐Water: Experience From Two Recent Studies

February 2019 | Robert B. Sowby, Steven J. Burian, (U. Utah), Christopher M. Chini (U. Illinois), and Ashlynn S. Stillwell (U. Illinois)

Two independent, simultaneous, and remarkably similar studies highlight the need for better data management in the water–energy nexus.

Journal – American Water Works Association

Conformance of Public Water Use Data to Benford’s Law

December 2018 | Robert B. Sowby

Water use data are essential to managing public water systems, but because most of such data in the United States are self‐reported, it is difficult to assess their accuracy. Benford’s law, which gives the expected frequency of leading digits in numerical data, could serve as one validation tool. This analysis tests whether Benford’s law applies to observations of potable water use by US public water systems. Almost all were found to conform to Benford’s law. This finding could serve as a quality check for historical water use data as well as projections.

A poster is also available.

Journal – American Water Works Association 110 (12)

Four Energy Metrics for Public Water Systems

October 2018 | Robert B. Sowby

Going beyond wire-to-water efficiency, this paper introduces important metrics for managing your water system’s energy use. These indicators address energy efficiency at the equipment, facility, and system levels with considerations for water loss, demand charges, cost of electricity, non-hydraulic loads, and changes over time. You’re probably already collecting the data you need for these metrics; now it’s time to apply them and improve.

American Public Works Association, Utah Chapter, 2018 Fall Conference

Correlation of Energy Management Policies with Lower Energy Use in Public Water Systems

November 2018 | Robert B. Sowby

This research shows that water utilities with documented energy management policies, plans, or programs will use, on average, 30% less energy than comparable water utilities without such policies, even after considering the water system’s size, water sources, and climate setting. This finding reinforces the value of voluntary, internal policies in making water systems more sustainable.

ASCE Journal of Water Resources Planning and Management

Comparison of Operational Energy Requirements in Publicly and Privately Owned U.S. Water Utilities

October 2018 | Robert B. Sowby

Economic theory predicts that privately owned water utilities should use less energy than their public counterparts. However, no statistically significant difference was found. This finding suggests that energy management policies and practices should regard both types similarly.

Utilities Policy

Statistical Model and Benchmarking Procedure for Energy Use by US Public Water Systems

2018 | Robert B. Sowby and Steven J. Burian (University of Utah)

This work introduces a statistical model to estimate a water system’s energy use as a function of its size, water source type, and climate setting. By considering such factors, the method enables more equitable comparisons of energy use among diverse water systems.

Journal of Sustainable Water in the Built Environment (ASCE)

New Techniques to Analyze Energy Use and Inform Sustainable Planning, Design, and Operation of Public Water Systems

May 2018 | Robert B. Sowby

This work offers three original contributions to help water systems manage their energy use and operate more sustainably: 1) a panel survey of annual, utility-scale energy intensities for over 100 U.S. water utilities; 2) a statistical model that predicts a water system’s energy use as a function of a few accessible variables and facilitates energy benchmarking; and 3) a high-resolution method to model energy use within a water distribution network to inform energy management decisions at multiple scales.

Doctoral Dissertation, University of Utah

Discussion of “Systems Analysis and Optimization of Local Water Supplies in Los Angeles”

July 2018 | Robert B. Sowby

This discussion estimates the energy and carbon savings that follow from a previous analysis of water management scenarios in the Los Angeles area and comments on the implications for further work.

Journal of Water Resources Planning and Management (ASCE)

Jordan Valley Water Redefines Sustainable Water Supply Through Energy Management

October 2017 | Robert B. Sowby, Steven C. Jones, Alan E. Packard (JVWCD), and Todd R. Schultz (JVWCD)

A major Utah water district reduced its energy footprint by 19% after a two-year energy management program. The district implemented both technical and organizational change in pursuing its vision to provide a more sustainable water supply.

Journal – American Water Works Association 109 (10)

Let’s Think Outside the Box. Wait … What’s IN the box? — An Exploration of Water System Energy Efficiency

August 2017 | Layne McWilliams (Cascade Energy), Steve Jones, and Raenee Bugarske (Rocky Mountain Power)

Water systems present a large opportunity for efficiency programs, but efforts to date have largely missed the mark. In reality, the key to conservation lies in understanding the flow of water and energy within the entire network. This paper describes how to “unwrap the box” to expose inefficiencies.

2017 ACEEE Summer Study on Energy Efficiency in Industry

Survey of Energy Requirements for Public Water Supply in the United States

July 2017 | Robert B. Sowby and Steven J. Burian (University of Utah)

National studies on drinking water systems’ energy requirements are sparse, and only limited empirical data have been available. This study adds considerable spatial and temporal detail to better characterize the requirements of 109 water systems in the continental United States.

Journal – American Water Works Association 109 (7): E320–E330

Hydraulic Modeling Finds, Fixes Chlorine Residual Gaps

June 2017 | Kayson M. Shurtz, Steven C. Jones, Robert B. Sowby, Daniel 'K' Woodbury (Riverton City), and D. Scott Hill (Riverton City)

After switching from wells to surface water, Riverton, Utah, experienced elevated levels of adenosine triphosphate in its water system. Hydraulic modeling helped solve the problem.

Opflow 43 (6): 28–30

Saratoga Springs: A Case Study of Installing Secondary Water Meters

2016 | Gordon Miner (Saratoga Springs) and Steve Jones

In 2012, when Saratoga Springs found that residents were using more than twice as much water as the system was designed for, the city decided to install meters on every connection. Although the process had its share of issues and complications, the results have been dramatic. Even before the metered usage showed up on the bill, the water use dropped significantly. By the time a rate restructuring took place and the usage actually affected the bill, most residents were already using the right amount of water.

American Water Works Association, Intermountain Section, Annual Conference

Web Applications to Support Municipal Water Works

2016 | Nathan Swain (Aquaveo) and Steve Jones

The interactive and intuitive nature of web apps makes them an excellent medium for creating decision support tools that harness cutting-edge modeling techniques and promote the work of engineers. We demonstrate how Tethys Platform has been applied to develop a web app that uses EPANET to simulate, visualize, and optimize water distribution systems. We discuss the pros and cons of using web apps to support municipal water works and illustrate with lessons we have learned while developing the EPANET app.

Download original presentation and videos

American Water Works Association

Energy Management in the Water Sector: A Major Sustainability Opportunity

2016 | Robert B. Sowby

Energy management in the water sector is an untapped sustainability opportunity with financial, environmental, and social benefits. Research and case studies demonstrate that energy reductions of 10% to 30% are typical for water utilities that pursue efficiency. Such solutions are cost-effective, prompt, and synergistic.

The 1st International Electronic Conference on Water Sciences

City of West Jordan Storm Drain Master Plan Dynamic Model

2015 | Joseph G. Hawkes

This presentation shows the benefits and constraints of dynamic storm drain modeling. Using West Jordan, Utah, as a case study, it describes model requirements, data, automated delineation with high-resolution LiDAR, model compilation, and problem solving.

American Public Works Association, Utah Chapter, Fall Conference

Dam Break Inundation Area Modeling and Mapping for an Emergency Action Plan

2015 | Benjamin D. Miner

The dam is failing. Now what? Emergency planning for dam breaks requires inundation maps to show what areas will be affected. This presentation describes regulations, methods, and models for preparing inundation maps in the context of Emergency Action Plans.

American Public Works Association, Utah Chapter, Fall Conference

Energy Intensity of Utah Water Utilities: Results of a 2015 Study

2015 | Robert B. Sowby

Water services require significant amounts of energy, and energy is typically a water utility’s largest controllable cost. While good data exist for other states, Utah’s position is relatively unknown. A 2015 study, the first of its kind in Utah, collected and analyzed energy data from dozens of water and wastewater utilities throughout the state. This presentation summarizes the study’s results and discusses some of the data issues encountered during the study.

American Water Works Association, Intermountain Section, Annual Conference

Compliance Strategies for High Levels of Arsenic, Nitrates, and Other Constituents in Groundwater

2015 | Benjamin D. Miner

Groundwater is a major source of safe and clean drinking water for most public water systems. However, many otherwise great sources are plagued with high levels of arsenic, nitrates, or other constituents regulated by primary drinking water standards. This presentation addresses sampling and treatment strategies, with discussion of the relative complexity and costs of implementation. Case studies are also discussed.

American Water Works Association, Intermountain Section, Annual Conference

Well Reconditioning

2015 | William S. Bigelow

Over time, water wells wear out. Sand production, biofouling, casing failures, and decreased yield are common problems. Reconditioning can restore a well to its original performance for much less than drilling a new well.

American Water Works Association, Intermountain Section, Annual Conference

Logan, Utah: A Case Study in Water and Energy Efficiency

2015 | Steven C. Jones, Paul W. Lindhardt, and Robert B. Sowby

Logan City, Utah, optimized its water system for both water and energy efficiency. Results include 32% energy savings, 17% water use reduction, and 40% fewer mainline breaks.

Journal - American Water Works Association 107 (8): 72–75

Quantifying Energy Use in the U.S. Public Water Industry: A Summary

2014 | Steven C. Jones and Robert B. Sowby

This article summarizes previous and recent research on the energy requirements of public water and wastewater services in the United States and briefly discusses some tools and resources for engineers working in this field. The intent is to inform industry professionals in order to better manage both water and energy resources.

Currents (Environmental & Water Resources Institute, American Society of Civil Engineers) 16 (4): 6–9

Individual Booster Pumps: Low Pressure Solution or Compliance Problem

2014 | Benjamin D. Miner

When a homeowner wants more pressure than a public water system can provide, an individual booster pump may be an option. This presentation describes the problems, solutions, risks, and regulations surrounding individual home booster pumps.

American Water Works Association, Intermountain Section, Annual Conference

Deep Drilling for Groundwater Yields Rewards

2014 | David E. Hansen

The Central Utah Water Conservancy District took a unique approach to discover new water for a growing population, with better-than-expected results. This is believed to be the largest single groundwater development project undertaken in Utah.

Water Online

Water System Optimization: Aligning Energy Efficiency, System Performance, and Water Quality

June 2014 | Steven C. Jones and Robert B. Sowby

Operational improvements identified through an optimization study can bring the system into a balance that achieves cost savings through energy efficiency, greater system performance and reliability, and improved water quality—with no capital expenses.

Journal – American Water Works Association 106 (6): 66–71

Master Planning Your Water System: Five Benefits and a Case Study

May 2014 | Steven C. Jones and Robert B. Sowby

Water, wastewater, and stormwater systems are vital to keep cities functioning. The public relies on them to supply clean water, remove waste, and prevent flooding. Master planning can help system managers provide these critical services more reliably.

Water Environment & Technology 26 (5): 30–32

Sandy City Storm Drain Model Update

January 2014 | Joseph G. Hawkes

This presentation describes the development of a new SWMM storm drain model for Sandy City, Utah. The project updated a previous model that overpredicted flows and didn’t accurately represent subbasins. Of note was the batch calculation of composite subbasin attributes.

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