WaterSense at Work Section 2.1: Metering and Submetering November 2023


WaterSense
at Work

Water Use Monitoring

2.1 Metering and Submetering

Best Management Practices for
Commercial and Institutional Facilities

*

EPA

WaterSense

November 2023

allons

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WaterSense® is a voluntary partnership program sponsored by the U.S. Environmental
Protection Agency (EPA) that seeks to protect the nation's water supply by transforming
the market for water-efficient products, services, and practices.

WaterSense at Work is a compilation of water efficiency best management practices
intended to help commercial and institutional facility owners and managers from multiple
sectors understand and better manage their water use. It provides guidance to help
establish an effective facility water management program and identify projects and
practices that can reduce facility water use.

An overview of the sections in WaterSense at Work is below. This document, covering
water metering and submetering, is part of Section 2: Water Use Monitoring. The
complete list of best management practices is available at

www.epa.gov/watersense/best-management-practices. WaterSense has also developed
worksheets to assist with water management planning and case studies that highlight
successful water efficiency efforts of building owners and facility managers throughout
the country, available atwww.epa.gov/watersense/commercial-buildings.

• Section 1. Getting Started With Water Management

• Section 2. Water Use Monitoring

• Section 3. Sanitary Fixtures and Equipment

• Section 4. Commercial Kitchen Equipment

• Section 5. Outdoor Water Use

• Section 6. Mechanical Systems

• Section 7. Laboratory and Medical Equipment

• Section 8. Onsite Alternative Water Sources

EPA 832-F-23-003
Office of Water

U.S. Environmental Protection Agency
November 2023

This document is one section from WaterSense at Work: Best Management Practices for Commercial and
Institutional Facilities (EPA-832-F-23-003). Other sections can be downloaded from

www.epa.gov/watersense/hest-management-practices. Sections will be reviewed and periodically updated
to reflect new information. The work was supported under contract 68HERC20D0026 with Eastern Research
Group, Inc. (ERG).

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Water Use Monitoring
Metering and Submetering

Overview

An important rule in water management
is that you can't manage what you don't
measure. Tracking a facility's total
water use, as well as specific end uses,
is key to successful commercial and
institutional facility water efficiency
efforts. Meters typically measure the
amount of water being supplied to a
campus or facility, while submeters
measure usage for tenant spaces or
specific activities, such as cooling
tower, process, or landscape water
use. Accurately measuring water use
can help facility owners and operators
identify areas for targeted reductions
and track progress from water efficiency upgrades. Submeters can also help identify leaks
and indicate when equipment is malfunctioning.

Meters and submeters can be integrated into a centralized building management system,
making it easy to track usage and implement a water management plan (refer to
WaterSense at Work Section 1.2: Water Management Planning at

www.epa.gov/watersense/best-management-practices for more information). These
systems are capable of electronically storing data from meters and submeters, reporting
hourly, daily, monthly, and annual water use. They can also trigger alerts when leaks or
other operational anomalies are detected.

Metering

For the purposes of this section, the term "metering" refers to the use of water meters
owned and managed by a utility to measure the total volume of water supplied to a
campus or facility. Meters measure and record usage data periodically for use in
customer billing and are typically associated with a single utility account.

Understanding Current Meter Infrastructure and Capabilities

A good first step in developing a water management program is understanding the water
meter infrastructure in place at a facility. Water meters supplied by a facility's water utility

WaterSense

Water meter box cover

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can typically be characterized as either a conventional (i.e., standard) water meter or an
advanced meter.

Conventional water meters require data to be retrieved by the utility on a periodic basis—
typically monthly or quarterly—for billing purposes. This infrequency of data collection
makes it more challenging for facility owners and operators to monitor water use and
respond quickly to problems.

Advanced water meters record and transmit data automatically. Advanced meters record
consumption data at least hourly and provide for daily—or more frequent—transmittal of
data to a central collection point.1 Advanced meters can provide detailed, real-time water
use measurements that can allow problematic trends and anomalies to be quickly
identified. While often used interchangeably with "advanced metering," the term "smart
meter" typically refers to a specific subset of advanced meters that is capable of
communicating readings to utilities for processing and analysis and sending billing and
consumption data back to the customer. Smart meters also typically provide additional
functions such as remote connect/disconnect, tamper detection, and outage monitoring.

All water conveyed to a facility should be metered, regardless of the source. Even if a
facility's water is supplied solely by an alternative source (e.g., municipally supplied
reclaimed water), a meter should still be installed to track and manage water use. If
multiple sources of water are supplied to a facility, each source should be metered
separately.

There may also be benefits in installing sewer meters or sewer deduct meters. Some
wastewater utilities offer a sewer credit or deduction based on water that does not enter
the sanitary sewage system. Typically, sewer usage is not separately metered at the
facility level. Therefore, most utilities estimate sewer charges based on the metered water
usage. This arrangement assumes that all the water that enters the property via the source
water meter leaves the property by the sanitary sewer system. In practice, however, some
of the water that is delivered to the property may not leave the property (e.g., landscape
irrigation water) or may not leave the property through the sewer system (e.g., evaporated
cooling tower water). Other examples include swimming pool water and water used in the
manufacturing or processing of goods. Installing deduct meters on activities such as
these can reduce sewer charges from participating utilities. Facility owners and operators
should reach out to their local utility providers to determine if a sewer deduction is offered
and to understand any metering and reporting requirements.

Although meter installation and management typically fall within the purview of the utility
rather than the customer, having a suitable meter and ensuring that it is properly
functioning are critical to accurate water measurement. There are many types and sizes of
meters intended for different uses, so it is important that your facility is properly equipped

1 U.S. Department of Energy (DOE), Federal Energy Management Program (FEMP). October 2022. Federal
Metering Guidance. www.energy.gov/femp/articLes/federaL-metering-guidance-energy-act-2Q2Q-sec-1QQ2g.

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with an appropriate one. Improper sizing or type can cause problems for the building. For
example, an undersized water meter can cause excessive pressure loss, reduced flow,
and noise. Oversized meters are not economical and do not accurately measure minimal
flow rates.2 In addition, many utilities charge customers a fixed fee based on the size of
the installed meter, so it is important to ensure that a facility's water meter is not
oversized. All utility-grade water meters manufactured and installed for domestic water
service by a water utility in the United States must comply with American Waterworks
Association (AWWA) standards.

Accessing and Utilizing Meter Data

If a facility is only equipped with a conventional water meter, facility owners and operators
can still monitor periodic consumption and cost data to:

• Verify utility bills;

• Compare utility rates;

• Manage budgets by assessing the impact of utility price fluctuations; and

• Identify long-term trends or anomalies such as sizeable leaks.

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What is Advanced Metering Infrastructure?

Advanced metering infrastructure (AMI) refers
to integrated systems that measure, collect,
and analyze energy and water usage data.
AMI includes hardware (e.g., meters, sensors,
alarms, displays), software, and
communications infrastructure. In addition to
the water meter, AMI hardware may also
include the following:

• Meter interface units (Mills), which
serve as the gateway between meters
and the data communications
network, transmitting the onsite data
and analytics to an information
management system. MIUs typically
consist of a battery and a computer
chip or radio transmitter.

• Sensors, including water quality
monitors, pressure sensors,
temperature sensors, and other types.
Alongwith consumption data, some
of this information may be available
within a customer portal.

• Remotely controlled valves, which
can be used to shut off or turn on
water service for customers.

Find out more about AMI within EPA's Using
Advanced Metering Infrastructure in a Water
Quality Surveillance and Response System at
www.epa.gov/sites/default/files/2021-
03/docu me nts/s rs_a m i_gu ida nce_20210223_
508_complete.pdf.

Facilities equipped with conventional
meters should consider installing
submeters, as described later in this
section, or other water use monitoring
devices such as data loggers. Data loggers
are portable compact devices that can be
used to retrieve and evaluate data more
regularly to supplement utility-managed
water meters. They are generally battery-
operated, stand-alone tools containing a
microprocessor, memory, and sensors for
measuring and recording one or more
variables overtime. Data loggers have the
advantages of being relatively affordable
and easy to install as a retrofit to existing
meters to directly collect data. Some
companies offer companion software to
help with data visualization and trend
analysis.

Advanced water meters—which are part of
advanced metering infrastructure (AMI)
operated by many water utilities—allow for
data collection to occur more frequently
and effortlessly, facilitating the
transformation of meter readings into
actionable data. Data acquired from
advanced meters are sent via wired or
wireless communication to a remote
database. Facility owners or other users
can subsequently access data through a
customer portal or online platform. If a
water utility has already installed advanced
or smart meters at the facility, facility
owners and operators should work with the utility to gain access to the customer portal
and begin monitoring water consumption more regularly. If a customer portal does not
exist, some water utilities may still be willing to work with commercial customers to
provide interval water consumption data. Some utilities also offer leak detection services
that are generated through advanced water meters.

The Energy Act of 2020 requires that all federal buildings be metered using advanced
meters or advanced metering devices where practicable (42 U.S.C. § 8253(e)). Additional

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information can be found in the Federal Energy Management Program's (FEMP's) Federal
Metering Guidance.3

Reviewing and understanding the data collected and communicated through AMI may
prevent the need for submetering within a facility. If the water utility does not have
advanced or smart meters installed, consider adding submeters. For more information
about using AMI to assist with water management, see WaterSense's AMI guide,
Improving Water Management Using Advanced Metering Infrastructure Data: A Guide for
Facility Managers at www.epa.gov/watersense/advanced-metering-infrastructure.

Submetering

For the purposes of this chapter, the
term "submetering" refers to the use of
facility-owned water metering
equipment to measure a subset of total
water use within individual buildings on
a campus, tenant spaces, or specific
water-intensive activities. Submeters
allow facility owners and operators to
track water usage more precisely. As
opposed to meters, which primarily
collect billing data for utilities,
submeters are designed with water
efficiency and operational improvement
in mind. In most cases, submeters do
not require separate utility accounts, and therefore should not result in any meter
connection fees or ongoing meter charges from the water utility. A facility can install and
monitor submeters on its own to understand and manage its water use.

Benefits of Submetering

Since utility-owned meters typically only measure the total volume of water supplied to a
property, submeters are often needed to monitor specific water-intensive buildings and
activities {e.g., irrigation, cooling). Submetering provides facility owners and operators
with information that can be used to optimize building and equipment operations. Recent
advances in metering technologies and information systems have improved functionality
and decreased costs, allowing real-time usage data to be collected in a more cost-
effective manner. If properly monitored and managed, these data can be used to:

• Improve equipment operations and reliability.

• Quickly identify and respond to leaks and equipment malfunctions.

3 DOE, FEMP, op. cit.

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• Prolong equipment life (and subsequently reduce capital investments).

• Properly allocate costs to tenants.

• Identify water efficiency improvement opportunities.

• Measure and verify water efficiency improvement projects.

• Benchmark building water use.

• Support efforts to obtain green building certifications.

The activities listed above can reduce water use, reduce costs for water and wastewater,
and improve overall building operations.

As with meters, submeters and associated infrastructure can provide for periodic and
automatic data retrieval. Data can be sent to a remote database for analysis and
translation into actionable recommendations.

Determining What to Submeter

Facility owners and operators should
consider installing separate submeters
to measure specific end uses that are
permanently plumbed, as indicated in
Table 1 on the next page. For more
information and additional
recommendations on metering and
submetering, review the U.S. Green
Building Council's LEED® rating
systems and the International Green
Construction Code® (IgCC®).4 5'6

Building owners and property managers
intending to use submeters to bill
tenants for water usage should be sure Submeter used to monitor reverse osmosis system
to understand state and local
regulations. Whether or not

4 U.S. Green Building Council (USGBC). LEED Operations ana Maintenance (O+M): Existing
Buildings. Version 4. Water Metering Credit, www.usgbc.org/credits/existing~huildings-retail-
existing-huildings-schools-existing-huildings-hospitality?return=/credits/Existing%20Buildings/v4.

5 USGBC. LEED Building Design and Construction (BD+C): New Construction. Version 4 and
Version 4.1. Water Metering Credit, www.usgbc.org/credits/new-construction-core-and-shell-
sehools-new-construction-retail-new-construction-data-
1?return=/credits/New%20Construction/v4.1.

6 International Code Council. 2021 International Green Construction Code.

https://codes.iccsafe.org/content/IGCC2021 P2/preface.

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submetering is permitted and specific requirements related to tenant billing can vary
depending on the locality.7

Table 1. Submetering Recommendations

Submeter Application

Recommendation

Tenant Spaces

Meter all tenant spaces individually.

Cooling Towers

Meter cooling tower make-up water and blowdown water supply
lines. A single make-up meter and a single blowdown meter can
record flows for multiple cooling towers if they are controlled with the
same system. Separately controlled cooling towers should have
separate make-up and blowdown water meters.

Heating, Ventilating,
and Air Conditioning
(HVAC) Systems

Individually or collectively meter HVAC systems with aggregate
annual water use of 100,000 gallons (379 kiloliters) or more or if the
facility has 50,000 square feet (4,600 square meters) or more of
conditioned space. Metered systems should include evaporative
coolers, humidifiers, mist cooling devices, and recirculating water
systems with a water connection, such as chilled water, hot water,
and dual temperature systems.

Steam Boilers

Meter the make-up water supply line to steam boilers with a rating of
500,000 British thermal units (Btus) per hour or greater. A single
make-up meter can record flows for multiple boilers.

Single-Pass Cooling
Systems

Meter any systems or equipment that use single-pass cooling water
and do not use a chilled water system or closed loop recirculation.

Irrigation

Meter irrigation systems that are automatically controlled.

Roof Spray Systems

Meter roof spray systems for irrigating vegetated roofs or thermal
conditioning.

Ornamental Water
Features

Meter make-up water supply lines for ornamental water features with
a permanently installed water supply.

Pools and Spas

Meter make-up water supply lines for indoor and outdoor pools and
spas.

Industrial Processes

Individually meter industrial processes consuming more than 1,000
gallons (3,800 liters) of water per day on average.

Alternative Water
Sources

Meter water use from alternative water sources, such as gray water,
rainwater, air handler or boiler condensate, or other sources
discussed in WaterSense at Work Section 8: Onsite Alternative Water
Sources at www.epa.gov/watersense/best-management-practices.

Other Processes

Meter any other process with a projected water use of 1,000 gallons
(3,800 liters) or more per day or 100,000 gallons (379 kiloliters) or
more per year.

7 National Conference of State Legislatures. January 15, 2016. Utility Submetering.
www.ncsl.org/energy/utility-suhmetering.

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Selecting Submeters

While the basic function of all water meters is to convert the physical flow of water into a
measurement of volume, a wide variety of meter designs and sizes are available in the
market. It is important to choose a meter that is suitable for the intended use. Submeters
that are installed for water management purposes and not used for revenue purposes are
not subject to AWWA standards.

In selecting the appropriate submeter size, it is critical to understand the building's size,
function, fixture types, usage occupancy, and peak population. These factors determine
the minimum and maximum flow rates and will assist in the selection of a properly sized
water meter. AWWA Manual M22, Sizing Water Service Lines and Meters, provides
additional guidelines for selecting and sizing utility-owned and installed water meters.8
Although this manual is intended primarily to inform the selection of utility-scale meters, it
may also be helpful in selecting and sizing submeters.

The appropriate meter type can be determined based on the intended use and flow rate.
Common meter technologies include the following:

• Positive displacement meters. Positive displacement meters directly measure
water volume by evaluating the rate at which a fluid mechanically displaces a
chamber. They are best suited for small commercial or institutional applications
because they have high accuracy rates at low flows and can precisely measure
peak flows.

• Velocity meters. Velocity meters such as turbine and propeller meters measure
water velocity and convert the measurement into volume. They are most
appropriate for continuous, high-flow applications and can be inaccurate at low
flows. These types of meters are not usually recommended for commercial,
institutional, or residential buildings because water flows are in constant
fluctuation, with very low minimum flow rates.

• Compound meters. Compound
meters integrate a positive
displacement chamber for low flows
and a turbine chamber for high flows.

They are good for large commercial or
institutional facilities because they
accurately measure across a range of
low flows and high flows.

• Electronic meters. Electronic meters
include electromagnetic meters and
ultrasonic flow meters.

8 AWWA. 2014. Sizing Water Service Lines and Meters (AWWA Manual M22, Third Edition).

Compound meter for reading both high and
low flows

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Electromagnetic meters use magnetic fields to induce an electrical current that is
proportional to the water flow rate. Ultrasonic flow meters—sometimes known as
acoustic flow meters—use ultrasonic acoustic vibrations to calculate flow rate
based on transit time or frequency shift. Electronic meters can be installed in-line
or clamped onto the exterior of a pipe and can be used in most commercial
applications regardless of the type of flow. They are ideal for measuring wastewater
or corrosive liquids without damage to sensors. Clamp-on models are non-
intrusive, low-maintenance, and do not cause a pressure drop in the water supply.
Portable models can be used to spot-check flow rates throughout a facility during a
water assessment or routine monitoring.

• Differential pressure meters. Differential pressure meters, including Venturi
meters and orifice plate meters, work by restricting flow into the meter and
measuring the difference in pressure between the inlet and outlet. Differential
pressure meters are commonly found in large water distribution systems, since
they are ideal for applications with high-flow and low-flow variation. They are
typically less expensive than other types of meters but require sufficient space.

When planning to submeter hot water use, consider selecting a meter intended for that
application.

Pacific Northwest National Laboratory's Water Metering Best Practices guide includes a
summary table comparing the characteristics of various metering technologies including
cost, flow range, meter size, typical applications, and other attributes.9

Some commercial vendors offer water monitoring programs or devices that are available
either in addition to or instead of water meters and submeters. These devices can be
connected to existing water meters or installed within the water line to help monitor water
usage and flow in real time. These devices can collect and store water use data and assist
facility owners and operators in tracking water use on a more regular basis than is
permitted through monthly utility bills. Many companies also offer a dashboard or other
management software to assist in analyzing water use trends, recommending areas to
improve efficiency, and generating reports. Further, these devices can be customized to
send alerts during periods of high or unexpected water use, during continuous flow
events, or when leaks are otherwise suspected. See WaterSense at Work Section 2.2:

Leak Detection and Repair at www.epa.gov/watersense/best-management-practices for
more information.

Installing and Maintaining Submeters

Following is a list of installation and maintenance best practices to ensure optimal
submeter operation:

9 Pacific Northwest National Laboratory. February 2022. Water Metering Best Practices. Prepared for DOE.
Table 1. www.pnnl.gov/main/publications/external/technical reports/PNN L-32074.pdf.

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• When installing a submeter, follow the manufacturer's instructions. Improper
installation can lead to metering inaccuracies.

• Ensure submeters are installed downstream of (after) the main water utility meter
so as not to affect utility-owned piping or the utility's ability to measure a facility's
total water use.

• Install submeters in an accessible location to allow for reading and repair. In
addition, ensure that the submeter location is protected from potential damage.

• To ensure uniform flow entering the submeter, do not install the submeter near
pipe bends. In general, place the submeter in a location with a straight length of
pipe equivalent to at least 10 times the pipe diameter downstream of the meter and
five times the pipe diameter upstream of the submeter.10

• Create a map indicating the location of all water supply meters and submeters to
be included in the facility water management plan.

• Include a strainer on all meters and submeters. Debris and sediment can enter a
meter and have an adverse effect on accurate measurement. An inline strainer on
the meter's inlet will collect debris and sediment and prevent it from entering the
meter body.11

• Since meters deteriorate with age, test them for accuracy and calibrate them on a
regular basis. AWWA recommends that utility-owned meters be tested, on average,
as follows:12

o Meter sizes 5/8 to 1 inch: Every 10 years
o Meter sizes 1 to 4 inches: Every five years
o Meter sizes 4 inches and larger: Every year

• Inspect and calibrate submeters according to manufacturer recommendations, or
more frequently, depending upon the type and size of the meter and its application.

Water Use Tracking and Integration Into the Water Management
Plan

Facility owners and operators should consider installing a water meter data management
system with remote communication capabilities that provides instant feedback on all
metered water use in a central location. This type of system makes it easier for facility
owners and operators to identify leaks or other abnormalities and better understand and
manage water use at the facility.

10 AWWA 2012, op. cit.

11 Ibid.

12 Georgia Environmental Protection Division. August 2007. Water Meter Calibration, Repair, and
Replacement Program. Page 7. www1.gadnr.org/cws/Documents/Meter Repair Replacement.pdf.

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A variety of programs and software are available to help analyze and visualize time-interval
water use data, including ENERGY STAR® Portfolio Manager®. Portfolio Manager is a free
interactive tool for managing the energy, water, waste, and greenhouse gas emissions of
any building type. The tool allows users to enter meter-level data based on monthly or
annual billing cycle. Once data is input into Portfolio Manager, there are tools to
understand metrics, monitor trends, and generate reports.

If the facility is not integrating metering data into a centralized data system, consider the
following best practices;

• Assign responsibility to track water use at least
monthly.

• Ensure that staff understand how to read the
meters and record data properly. Pay special
attention to the units that the meter uses—
gallons, cubic feet, and hundred cubic feet are
common units for water meters. Also, ensure
that staff record the numerical values properly.

Meters often include one or more trailing zeros
that must be added after the numerical dial
reading.

• Plot total water use and submetered data
monthly and examine data for unexplained
fluctuations.

• Evaluate trends and investigate and resolve any unexpected deviations in water
use.

Additional Resources

American Waterworks Association (AWWA). 2012. Water Meters—Selection, Installation,
Testing, and Maintenance (AWWA Manual M6, Fifth Edition).

AWWA. 2014. Sizing Water Service Lines and Meters (AWWA Manual M22, Third Edition).

U.S. Department of Energy (DOE), Federal Energy Management Program (FEMP). October
2022. Federal Metering Guidance, www.energy.gov/femp/articles/federal-metering-
guidance-energy-act-2Q2Q-sec-10Q2g.

DOE, FEMP. Water Metering Resources, www.energy.gov/femp/water-metering-
resources.

EPA's WaterSense program. September 2022. Improving Water Management Using
Advanced Metering Infrastructure: A Guide for Facility Managers.

www.epa.gov/watersense/advanced-metering-infrastructure.

This meter reads 201,670 cubic feet

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National Conference of State Legislatures. January 15, 2016. Utility Submetering.
www.ncsl.org/energy/utility-submetering.

National Science and Technology Council. October 2011. Submetering of Building Energy
and Water Usage: Analysis and Recommendations of the Subcommittee on Buildings
Technology Research and Development.

https://sftool.gov/Content/attachments/submetering of building energy and water usa
ge.pdf.

Pacific Northwest National Laboratory (PNNL). March 1, 2015. Metering Best Practices: A
Guide to Achieving Utility Resource Efficiency, Release 3.0. Prepared for DOE.
www.wbdg.org/ffc/doe/national-laboratory-criteria/metering-best-practices.

PNNL. February 2022. Water Metering Best Practices. Prepared for DOE.
www.pnnl.gov/main/publications/external/technical reports/PNNL-32074.pdf.

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Disclaimer

This document was prepared as an account of work sponsored by the United States Government.
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and opinions of authors expressed herein do not necessarily state or reflect those of the United
States Government nor any agency thereof.

v>EPA

United States Environmental Protection Agency
(4204M)

EPA 832-F-23-003
November 2023
www.epa.gov/watersense
(866) WTR-SENS (987-7367)

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