DEC
PUBLICATION
Division of Water
Water Conservation Manual
For Development of a
Water Conservation Plan
January 1989
Re-printed May 1998
New York State
Department of Environmental Conservation
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DEC
PUBLICATION
Division of Water
Water Conservation Manual
For Development of a
Water Conservation Plan
January 1989
Re-printed May 1998
New York State
Department of Environmental Conservation
PREFACE
This A Water Conservation Manual for Development of a Water
Conservation Plan @ has been printed and distributed by the New York State
Department of Environmental Conservation (NYSDEC), Division of Water.
It is intended to help local water supply systems to comply with state
legislation that requires a water conservation program as a part of any new application to
NYSDEC for a Public Water Supply Permit.
The manual is a Ahow to@ guide that addresses a large number of water
conservation measures such as water metering, the conduct of a system water audit, the
detailed study of water demand, reduction in system water loss, and reduction in system
water demands.
If you have any questions or comments please call the Division of Water's
Bureau of Water Resource Management in NYSDEC at (518) 402-8086. You may also email
your questions or comments to the attention of "Public Water Supply Program" at
[email protected]
i
List of Tables
Table 1. Meter Type and Recommended Applications ............................................................................ 5 Table 2. Percentage of Total Flow Through Domestic Meters at Various Rates ..................................... 6 Table 3. Under-Registration ofMeters According to Age ....................................................................... 6 Table 4. Information Sources for Water Demand Studies...................................................................... 20 Table 5. Leak Losses for Circular Holes Under Different Pressures...................................................... 29 Table 6. Leak Losses for Joints and Cracks Under Different Pressures ................................................. 29 Table 7. Reduction Factors:Water Rate Increase .................................................................................. 39 Table 8. Potential Energy Savings ......................................................................................................... 43 Table 9. Approximate Installation Rate of Retrofit Devices .................................................................. 46 Table 10. Recommended Water Conserving Landscape Criteria for Planned Unit Developments .......... 48
List of Worksheets
Water Metering
Worksheet 1. Sample Meter History Record Form.................................................................................. 8 Worksheet 2. Water Metering............................................................................................................ 9-
Water Supply Audit
Worksheet 3. Total Supply to the System for Calendar Year ................................................................ 12 Worksheet 4. System Water Audit................................................................................................... 15- Worksheet 5. Water Utility Average Variable Costs of Production ...................................................... 18 Worksheet 6. Wastewater Utility Average Variable Costs of Treatment .............................................. 19
Water Demand Forecast
Worksheet 7. Historic Water Demand ............................................................................................. 21- Worksheet 8. Percentage Trends in Water Demand .............................................................................. 24 Worksheet 9. Projection Year Percent Change ...................................................................................... 25 Worksheet 10. Future Year Projections of Water Demand ...................................................................... 26
Leak Detection and Repair
Worksheet 11. Leak Repair Report.................................................................................................... 30- Worksheet 12. Preliminary Planning for Leak Repair Program......................................................... 32- Worksheet 13. Leak Detection Survey Daily Log ................................................................................... 34 Worksheet 14. Leak Detection and Repair Project Summary.................................................................. 35 Worksheet 15. Leak Detection Project Cost Effectiveness ...................................................................... 36
Acknowledgments
This manual was conceived and written in 1989 by William Nechamen of the Bureau of Water Resources (now the Bureau of Water Permits) in the New York State Department of Environmental Conservation.
The appendix on public information and education, published for the first time in the 1998 re-printing, was written in 1993 by William Nechamen of NYSDEC and Jeff Featherstone of the Delaware River Basin Commission.
The 1998 re-printing was composed in WordPerfect (Version 6.1 for Windows) by G. Gordon Behn of the Bureau of Water Permits in NYSDEC.
iii
I. Introduction
In July of 1988, the Governor of New York State signed legislation requiring a water conservation program as a condition of a water supply permit.
To assist local governments in complying with this new requirement, the law directed the New York State Department of Environmental Conservation (DEC) to develop a model water conservation plan which includes beneficial short- and long-range water conservation procedures reflecting local water resource needs and conditions. This manual serves as a model to help advise local officials regarding water conservation techniques which individual suppliers may use to conserve water.
In addition, the Statewide Water Resources Management Strategy, approved in January 1989, recognizes the importance of water conservation and directs DEC to assist local water suppliers with water conservation programs. The strategy cites the delicate balance between water supply and demand. Also, the strategy also notes that, in many areas of the state, demand is catching up with available supplies. Increased water demand and contamination of supplies have placed more stress on existing water resources.
Why Should Municipalities
Conserve Water?
Other than maintaining a supply-demand balance, municipalities conserving water will realize the following benefits^1 :
C increased ability to handle emergencies such as drought mechanical failures, or water contamination;
C variable cost savings in energy and chemicals from reduced production, treatment, and consumption water;
C deferment of expenditures for expansion of water supplies or wastewater treatment facilities by allowing an existing water supplies and/or wastewater treatment systems to serve increasing populations;
C greater efficiency and increased capacity in wastewater treatment facilities;
C improved in-stream flows in source water and related water resources and higher quality in wastewater receiving bodies; and
C alleviation of competing demands for water resources.
How Do Users Benefit
from Conservation?
Water heating costs can be cut by nearly one-third, and water and sewer bills will decrease under conservation programs. Where conservation can postpone or reduce the size of expanding existing facilities or developing new supply sources, water conservation is often the most cost-effective alternative. Even where conservation programs necessitate water rate increases, the average consumer will likely pay less than if the program had not been undertaken
various components of a system=s water demand, as identified in a system water audit. Sectors include interior residential, exterior residential, commercial, industrial, public and unaccounted-for water uses. A dimension is a flow rate corresponding to a specific condition, such as average daily flow, peak daily flow, and peak hourly flow.
Some conservation benefits decrease over time, and the effectiveness of a conservation approach might eventually diminish if additional actions are not taken. In addition, a particular method might achieve significant benefits by itself while adding only marginal additional benefit to those achieved by a method already underway.
II. Information Requirements
Before the components of a conservation program can be determined, it is necessary to compile a water supply audit and water demand evaluation for an individual water system.
A. Water Metering
1. Metering for Information
Meters are prerequisite for other conservation methods, such as water pricing, education and leak detection. Meters provide information about water consumption necessary to identify users with leakage problems, and carry out repair programs that cannot be efficiently carried out without the consumption information only meters can provide. Meters provide water accountability, without which it is not possible to know the results of a conservation effort. The American Water Works Association officially advocates 100 percent metering of water customers.^4
Without meters, customer bills cannot be based on volumes of water used. Once meters are in place, they allow for various water rate structures which can help influence water use. Metered water rates, with timely and understandable billing, provide proven incentives in reducing unnecessary water uses, repairing leaky plumbing, and installing more efficient water-using fixtures. In addition, meters are necessary for efficiently maintaining water systems, accurately assessing demand, and determining appropriate capital expenditures.
2. Metering for Incentive
Metered water rates provide a direct incentive for user based water conservation, because meters allow water utilities to charge for water based on actual usage. Savings are greatest during warm weather months when water is used for landscape irrigation. However, even indoor use during winter months tends to decrease after meter installation and unit billing because building owners are encouraged to fix leaks and use more efficient plumbing and appliances.
Using metered rates as an incentive to conserve requires frequent meter reading and billing to show a clear pattern to the consumer. A quarterly meter reading and billing schedule based on actual water consumption is the minimum recommended.^5 Timely billing is particularly important where seasonal water use is a concern. Large water users should be billed more frequently. Some water utilities around the country have begun more frequent billing of residential accounts.
Experience in New York State has shown a total demand reduction of over 20 percent after first time metering. In Kingston, a universal metering program resulted in reduced peak daily and hourly loads, from 8 MGD in 1957 to 4.3 MGD in 1962 (both years were dry). Average water use went from 5.5 MGD in 1957 to 4.0 MGD between 1960 and 1963. The program resulted in postponement of a water treatment plant expansion and allowed the city to determine unaccounted-for water and to evaluate production costs. In New York City, the Jamaica Water Supply Company recently completed metering 90,000 residential accounts in its Queens service area, and has seen a 20 percent average
usage reduction. In both the Kingston and New York City cases, the new meters were accompanied by regular billing with rates based on water used.
A comprehensive metering program includes source or master meters and service meters, and it considers maintenance and record-keeping needs.
3. Types of Meters
a. Master Meters
Master or source meters measure the water supplied from sources, storage facilities and treatment plants. They are designed for accountability, rather than sale, of water. Obtaining data from master meters is the first step in determining if a system has unaccounted-for water.
All water meters tend to under-register. Master meters, however, can also over-register by as much as 25 percent^6 due to improper setting, sizing or gearing, poor water quality, reading errors, or air or jetting action.
Master meters should be tested for accuracy at least once a year.^7 Tests can be conducted in place with a Pitometer or comparative flow meter. A pitot tube measures The flow rate by comparing differential pressures and converting the square root of the pressure difference to flow units. Under good conditions, accuracy is within 3 percent. Because turbulence decreases accuracy, pitot installations should be made with 10 to 20 pipe diameters of straight pipe from any obstruction.^8
b. Service Meters
Service meters include residential and commercia meters. An efficient water supply system should have a service meter at every service connection, including public facilities which may not directly pay for service. As with master meters, it is important that meters be properly sized and installed, that they be maintained, and that records be kept assisting meter and system maintenance and system planning decisions.
4. Costs and Benefits to the Utility
For a water system not fully metered, a metering program is admittedly costly. Installing, maintaining, and reading meters can represent a significant portion of a utility=s costs.^9 Furthermore, switching to full metering causes revenues to become more uneven as income reflects the ebbs and peaks of annual demand. Depending on the size and type of meters used, and installation conditions and requirements, the cost of metering can range from $50 to over $300 a service, with even higher costs for very large service connections.
In most instances, however, the benefits derived from meters far outweigh their cost. In terms of the water conservation message alone, metering costs of up to $500 per service are likely to be cost effective in the long term due to reductions in peak and average demands.^10 Meters also engender equity in customer charges and the ability to use various pricing policies.
Utilities can find ways to bring the cost of metering down. One way is to use less expensive residential meters made with plastic and periodically replaced rather than repaired and returned to service. Another way is to contract out meter installation to a private firm, rather than the utility installing its own meters.
6. Meter Maintenance
Water meters cannot perform their required function if not properly maintained. All meters slip to varying degrees with passing time. Sand, debris and minerals passing through the measuring element increase the tolerances in the chamber, allowing more water to pass through than is recorded. As meters begin to slip, low flows fail to register, and under-registration continues to increase as the wearing process continues. Up to 23 percent of all water flows in domestic meters can fail to register. Tables 2 and 3 show the average flow rates of domestic services and average under-registration of meters by age.^11
Table 2. Percentage of Total Flow Through Domestic Meters at Various Rates.
Range of Flow Rates Water used in this range of flow rates (In GPM) (As percentage of total water used)
0.00 - 0.25 13. 0.25 - 0.50 3. 0.50 - 1.00 6. 1.00 - 2.00 13. 2.00 - 4.00 43. More than 4 20.
Table 3. Under-Registration of Meters According to Age.
Age of Meters (years)
Inaccurate Meters (per cent)
Minimum Registrable Flow (gpm)
0-9 5 0. 9-19 20 0. 19-29 50 1. More than 29 84 1.
A regular program of meter testing and maintenance will minimize under-registration, resulting in less unaccounted-for water, more stable water revenues to the supplier, and more appropriate price signals for the customer. Master meters and large commercial meters should be tested annually. A program of sample testing of residential meters could help determine an optimal repair or replacement schedule.
The American Water Works Association recommends that meters remain in service until they fail to register within accepted accuracy limits. A residential meter should register between 98.5 percent and 101.5 percent of actual flow at flows between 2 and 15 gallons per minute. At a flow rate of 1/ gpm, 95 percent to 101 percent accuracy is considered appropriate. It may be necessary to remove and test a representative sample of residential meters which includes the range of types, makes and ages and includes meters that may serve regions with different water sources. An initial sample of 5 percent of each group of meters will yield approximate accuracy rates for all residential meters.
Meter testing should be done for at least three flow rates: 1/4, 2, and 15 gallons per minute. A rough estimate of total meter accuracy can be made by multiplying the meter accuracy at each of the
three test flow rates by a percentage of use at that flow by .13, .72 and .15 respectively, then adding the products. The average under-registration should also be used in determining metered water sales for a water system audit. Based on sample findings, a priority schedule should be developed for calibrating, and repairing or replacing as needed all residential meters over a 10-year rotating schedule.
7. Meter Records
An appropriate meter program must include accurate record-keeping. Meter history cards could be kept, or data could be maintained on computers, providing information on meter size, make, type, date of purchase, location, and tests and repairs. A sample form follows on page 8 as Worksheet 1.
8. Advanced Meter Technologies
A common impediment to an appropriate meter reading schedule is the difficulty of gaining access to private residences to read the meters. Estimated readings are often the rule rather than the exception. Once the meter is read, consumers often are hit with a very high water bill to make up for past, unbilled use. At the very least, this causes bad public relations. It also eliminates the price- related feedback on which conservation programs depend.
Remote reading registers can circumvent the access problem by allowing meter readers unlimited access to meter information. Remote read systems are attached to indoor meters either through an electric pulse or a flexible cable. The electric systems require no external power source. They typically require a meter reader to visually read and copy information.
There are also hand-held computer systems which electronically read meters through a plug in the remote register and are later loaded down to an office computer. This computer maintains meter records and processes water bills. Such a system can record the time and date of the reading, can flag information based on certain conditions (such as a reading over a certain percentage more than the average reading), and can even print out a bill right on demand.
New technologies currently under development will eliminate the need for meter readers while providing added flexibility in the schedule and frequency of meter reading. These remote registration systems will obtain readings through telephone data hookup or by radio signal. Telephone systems can be designed as a Acall out@ in which a central computer calls out to meter locations and logs data at the rate of about 8 to 10 reads per minute. A Acall in@ system relies on each meter using the building phone line to automatically call readings out to a central computer on a scheduled basis. Radio read systems use radio signals from a mobile unit that drives down the street. Currently, the Spring Valley Water Company in Rockland County is developing a call-out system, and the New York City Bureau of Water Register has plans to conduct a pilot study of all three systems. With any remote meter reading system, it is necessary to periodically calibrate the remote device with the actual meter. An annual check of the actual meter will assure system operators and customers that the remote system represents actual water use.
9. Water Metering in the Conservation Program
Worksheet 2, on pages 9 and 10 below, can help you to define the water metering element of your conservation program. By completing the worksheet, you can determine the degree to which your present metering efforts meet the stated goal and objectives. You can then identify future efforts that can bring about the needed improvements to your metering program.
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
____________________________
Worksheet 2: Water Metering.
The following information would aid in development and assessment of your water conservation plan.
GOA L: To provide an accurate measurement and record of water use, and promote water conservation
Recommended Actions: C 100 percent metering of all water system connections, including public buildings.
C Ongoing metering program with regular program of testing, recalibrating, repairing or replacing meters as needed. Residential meters will be tested at least every ten years. Large meters should be tested annually.
C Quarterly meter reading and prompt billing with water rates reflecting amount of water used. Large services to be read more frequently.
A. Past and Present Efforts:
- What percent of your system is metered? ________________%
- Number of operable meters in system: __________________
List percentage of users metered by category:
Residential ______% Industrial _____% Commercial______% Public ______% Other _____%
- How often are master (or source) meters calibrated? ___________________________
- How often are the master meters read? ______________________________________
- How often are customer meters read? _______________________________________
- What is the general condition of your meters?
Master ______________________ Customer _______________________
- Do you use externally read meters? ____ YES ___ NO. If yes, _______%
- Do you have an ongoing program to monitor, check, repair, and replace meters? ____YES ____ NO
If YES, briefly explain your program:
(Worksheet continues on next page)
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
____________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
____________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
____________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
____________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
____________________________________________________________________________
(Worksheet 2 continued)
- Has your metering repair and calibration program been effective in reducing the amount of unaccounted-for water, increasing revenues, or decreasing demand?
Briefly explain:
- What problems, if any, prevent the accomplishment of an optimal metering program? Include, if applicable, cost and labor and institutional impediments.
- Estimate how much is spent on the metering program per year
Meter installation: $__________ Meter repair and calibration $__________ Meter reading $__________
B. Future Efforts:
- What long range goals exist for improving your metering program?
- What measures are planned to implement these goals?
- What is the timetable for achieving these goals?
- What is the approximate cost and funding source for these efforts?
Beginning Volume - Ending Volume = Change in Volume
The sum of the Changes in Volume = the Total Storage Adjustment (Add to Worksheet 4, Line 2a)
Any other known additions or losses to the total supply should also be added to the Worksheet 4 on Line 2b.
Worksheet 3: Total Supply to the system for Calendar Year _______
MONTH
SOURCE A (Units)
SOURCE B (Units)
SOURCE C (Units)
MONTHLY TOTAL
January
February
March
April
May
June
July
August
September
October
November
December
SOURCE TOTALS
TOTAL ANNUAL SUPPLY TO THE SYSTEM (Add to Worksheet 4, Line 1):
2. Quantify Authorized Metered Water Use
All authorized uses of water, including unbilled public uses, should be metered and quantified by category in the same time period as the water source audit. The first step in quantifying metered watered use is to identify all metered accounts. Metered accounts should then be sorted by type of use, including industrial,institutional, commercial, residential, public purpose, wholesale sales to other jurisdictions, and other possible breakdowns, such as categories of residential use. Uses should also be broken down by meter size.
The uncorrected, total, metered water use must then be adjusted for meter reading lags, since most meters are probably not read on the beginning and ending dates of the audit period. To correct for meter lag, figures must be prorated for the first and last billing period of the audit period. It is best if the audit period begin and end during the winter months so outside watering does not create a variation in water use.
To correct for meter lag, for each meter route, take the total amount of water sold for the earliest billing period ending after the start of the audit period. Adjust the total bymultiplying it by the average percentage of days of the billing period which fall between the first day of the audit period and the meter reading date. For example, if meters for a particular route are read in December and in March, and the audit period begins on January 1, determine the average number of days between January 1 and the March reading, divide that by the
average number of days between the December reading and the March reading to determine the portion used during the audit period, and m ultiply that ratio by the total water use for the route during the m eter reading period. For the end of the audit period, take the earliest meter reading period ending after the audit period and determine the portion which falls before the end of the audit period.
To make the adjustments more meaningful, it would be useful to separate large water-using accounts from the average readings and prorate themseparately. The adjusted metered water use for the audit period should be added to Line 5 of the Worksheet 4 (on page 15 below).
If meter records are not maintained in a manner which allows for metered use quantification, a plan should be undertaken to maintain appropriate records. Many water systems now use computers for billing purposes. Computerized billing records can easily be maintained so that accounts are organized by type, meter size and geographic area. Account data can also include meter maintenance histories as well as water consumption data. With well maintained records, not only are system audits easily undertaken, but accounts can be screened to show unusually high or low demand, which can in turn indicate leakage or a malfunctioning meter.
3. Quantify Authorized Unmetered Uses
Authorized unmetered water uses are often called Aauthorized unaccounted-for water.@ Such uses include public buildings and parks, fire fighting, and street cleaning. While all public services should be metered, it is obviously impossible to precisely quantify water runni ng through fire hydrants. Such uses can, however, be estimated as part of the system water audit. Authorized unmetered uses may include:
C Firefighting C Construction sites C Landscaping in large public areas C Sewer flushing C Firefighting training C Water quality and other testing C Decorative water facilities C Street cleaning C Flushing of mains C Process water at treatment plants C Swimming pools C Schools C Storm drain flushing
Where water is used in tanks, (i.e., street cleaning) , volumes can be estimated by multiplying the volume of the tank by the number of times it is filled. Where water is applied directly from a pipe, (i.e., fire fighting), the average discharge rate can be m ultiplied by the total tim e during which it flows. In the absence of records, volumes will have to be estim ated. Fire fighting and training use might be more easily estimated if a fire department requires a Arun report@ any time a unit responds to a call. Run reports can be culled for instances where hydrant water was used, with an average rate per use as a multiplier.
Main flushing use can be easily estimated if the utility maintains logs of flushing activities, including the location of the main or blowoff and the length of time of flow. Again, an absence of records would require an estimate of the number of flushing activities and average volumes of flow. Stormdrain and sewer flushingcan be estimated by the same method of main flushing if the water is supplied directly fromwater mains. If water is transported by truck, multiply the trucks= capacities by the number of times tanks are filled to determine water use. The responsible maintenance department should be ur ged to maintain records of hydrant use or tank filling. Sewage treatment plants which take additional water for treatment purposes should likewise be urged to maintain records of water use. Such uses should be metered.
Landscape use in public areas (parks, golf courses, cemeteries, playgrounds, highway median strips, etc.) can be estimated by comparing use with metered landscap ed areas having similar uses and watering schedules. Frequency and duration of watering can be obtained from the persons responsible for landscape maintenance. Use from time-controlled irrigation systems can be calculated easily from the average flow and tim e of operation. Water uses from decorative fountains and pools should also be estimated. Information on draining and refilling, and also on average daily evaporation can be obtained from facility operators.
vandals. A program of meter locking or use of spray caps in areas where hydrants are opened during hot weather could help minimize such losses.
System valves should be checked periodically for malfunction. For instance, altitude control valves on storage tanks might be broken or set improperly, allowing the tank to overflow. Pressure relief valves which are set too low might cause spill when pressures reach the high range. Improperly set pressure-reducing, pressure-sustaining and pressure-maintaining valves can cause spills at altitude control valves, pressure relief valves or surge control valves. Surge relief valves, if set too low, can cause unnecessary blowoff to the atmosphere. A failed pump discharge valve may allow water to discharge from the distribution system back down the well. When problems are discovered during routine inspections, possible water losses should be estimated.
Leakage represents the largest share of unauthorized water use. Section III.A.1 of this manual provides guidance in leak repair record keeping and leak detection.
Worksheet 4, following, should be filled out to estimate categories of water use and waste, using the preceding sections for guidance. By analyzing the results, it is possible to estimate and forecast water uses and prioritize conservation programs.
Worksheet 4: System Water Audit
LINE ITEM
WATER VOLUME
Subtotal^ UNITS
Cumulative Total
1 UNCORRECTED TOTAL WATER SUPPLY to the distribution system (Total of master meters)
2 ADJUSTMENTS TO TOTAL WATER SUPPLY:
2a Change in System Storage (+ or -)
2b Other Contributions or Losses (+ or -)
3 TOTAL OF ADJUSTMENTS (+ or -)
4 ADJUSTED TOTAL WATER SUPPLIED to the distribution system (Add Line 1 and Line 3)
5 METERED WATER DELIVERIES, corrected for meter lag
6 CORRECTED TOTAL UNMETERED WATER (Subtract Line 5 from Line 4)
7 AUTHORIZED UNMETERED WATER USES:
7a Unmetered Public Buildings
7b Firefighting and Firefighting Training
7c Main Flushing 7d Storm Drain Flushing
7e Sewer Cleaning
Worksheet 4: System Water Audit
LINE ITEM
WATER VOLUME
Subtotal^ UNITS
Cumulative Total 7f Street Cleaning
7g Landscaping in Public Areas
7h Schools
7i Decorative Water Facilities
7j Swimming Pools
7k Construction Sites
7l Water Quality and Other Testing
7m Process Water at Treatment Plants
7n Other Authorized Unmetered Use
8 TOTAL AUTHORIZED UNMETERED WATER (Add Lines 7a through 7n)
9 WATER LOST TO LEAKS SINCE REPAIRED
10 TOTAL UNACCOUNTED-FOR WATER (Subtract Lines 8 and 9 from Line 6)
11 IDENTIFIED WATER LOSSES:
11a Source Meter Error (+ or -)
11b Customer Meter Under-registration
11c Accounting Procedure Errors
11d Illegal Connections
11e Malfunctioning Distribution System Controls
11f Theft
12 TOTAL IDENTIFIED WATER LOSSES (Add Lines 11a through 11f)
13 UNIDENTIFIED LOSSES (POTENTIAL LEAKAGE) (Subtract Line 12 from Line 10)