Section 1

Conservation Planning Guidelines
South Central Texas Regional Water Planning Group

Introduction

Aggressive conservation measures have been helping communities in Texas and throughout the world reduce demand as an alternative to developing new water supplies. Large municipal purveyors, such as the San Antonio Water System, have award-winning conservation programs. Many of the elements of conservation programs have been developed into Best Management Practices by agencies such as the California Urban Water Conservation Council and the Edwards Aquifer Authority. The South Central Texas Regional Water Planning Group has chosen the advanced conservation option in projecting water demands for the future. The Conservation Practices and water saving tips in this document will assist communities in meeting those projections.

Successful conservation programs will help to expand the existing water supply of the region by reducing demand. At a minimum conservation programs need to address two means of reducing water use: change of behavior and change of equipment. Turning off the water when it is no longer necessary for rinsing, irrigating, or other productive uses, plays a significant role in reducing demand. Replacing older, less efficient equipment, with new modern equipment can realize water savings mechanically.

These Conservation Planning Guidelines of the South Central Texas Regional Water Planning Group are designed to assist new and existing conservation programs to pick the best of available options to help reduce water demand. Conservation programs are tailored to meet the specific demand profile of communities or regions, as defined in planning documents. As such they will have unique elements regarding the cost of water, the type of promotional activities, and the specific measures which are combined within a program. However, past success in conservation efforts of communities throughout Texas and the western United States has led to the development of a basic framework for program development referred to as conservation best management practices. This Planning Guidelines document is organized into a description of specific Conservation Practices which can be used to meet the demand reductions anticipated in the South Central Texas Regional Water Plan’s Option L-10, Demand Reduction.

Each Conservation Practice comprises a grouping of conservation measures. It contains some information that will assist a utility or water district in achieving its goals, and suggestions for how to calculate anticipated water savings. Conservation measures are the basic elements of a practice or program. They include for example toilet retrofits or showerhead replacements.

Each practice description is followed by some coverage prerequisites that will assist a planning unit in designing a successful program. The final section of each Practice is a set of assumptions or equations that will assist in determining the potential water savings.

Conservation practices include system-wide measures, such as System Water Audits, Leak Detection and Repair, Metering of all New Connections and Retrofit of Existing Connections, and Water Waste Prohibition. Practices directed at the customer or general public include Public Information Programs and School Education Programs.

Other conservation practices include measures intended to assist residents and businesses in the installation of new or retrofitted equipment that is water efficient. These include Water Survey Programs for Single- and Multi-Family Residential Customers with Residential Plumbing Retrofit Programs, Residential Ultra-Low-Flush Toilet (ULFT) Replacement Programs, High-Efficiency Washing Machine Rebate Programs, Hot Water on Demand Systems, and Conservation Programs for Industrial, Commercial, and Institutional (ICI) Accounts including ICI ULFT Replacement Programs.

South Central Texas is located in a semi-arid ecoregion on the edge of the Chihuahua desert. High temperatures and long periods without a significant amount of rainfall place a premium on outdoor water conservation. Conservation practices directed at outdoor water use include Landscape Conservation Programs and Incentives and Rainwater Harvesting Systems.

Following the section on Conservation Practices is a list of water saving tips prepared by the Texas Water Development Board. The tips are aimed for the residential water user, and can be used by municipal utilities and water districts in their public information or education programs. The conservation practices described in this document are listed below. References at the end of the Guidelines give additional facts including anecdotal information regarding successful conservation programs that have implemented these practices.

Conservation Practices

1. System Water Audits, Leak Detection and Repair

2. Metering of all New Connections and Retrofit of Existing Connections

3. Water Waste Prohibition

4. Conservation Pricing

5. Public Information Programs

6. School Education Programs

7. Water Survey Programs for Single and Multi-Family Residential Customers
(Including Plumbing Retrofit Programs)

8. Residential Ultra-Low Flush Toilet (ULFT) Replacement Programs

9. High-Efficiency Washing Machine Rebate Programs

10. Hot Water on Demand Systems

11. Conservation Programs for Industrial, Commercial, and Institutional Accounts
(Including ULFT Replacement Programs)

12. Cooling Water Recirculation Systems

13. Landscape Conservation Programs and Incentives

14. Rainwater Harvesting Systems

15. Agricultural Irrigation Conservation Programs

Conservation Practice 1: System Water Audits, Leak Detection and Repair

Description

System Water Audit and Leak Detection and Repair programs are effective methods of accounting for all water usage within a service area and are essential to a sound water management program. Under this Conservation Practice, the purveyor needs to conduct annual pre-screening system audits to determine if full-scale system audits are necessary. If determined to be necessary, the purveyor then will conduct a full distribution-system audit.

In order to reduce water losses due to leakage, the purveyor needs to maintain a Leak Detection and Repair Program and needs to repair leaks when detected. Unaccounted water losses need to be no more than 10 percent of total water in the system. The purveyor needs to make every effort to inform customers when leaks exist on the customers’ side of the meter.

Coverage Conditions

To realize this practice, the purveyor needs to accomplish the following:

1. Annually complete a pre-screening system audit to determine the need for a full-scale system audit. The pre-screening system audit needs to be calculated as follows:

a. Determine metered sales and other system verifiable uses;

b. Determine total supply into the system; and

c. If metered sales plus other verifiable uses represent less than 90 percent of total supply into the system, a full-scale system audit is necessary.

2. Annually conduct a distribution system water audit using methodology consistent with that described in AWWA's "Water Audit and Leak Detection Guidebook" (if applicable);

3. Perform distribution system leak detection when warranted and repair identified leaks when cost-effective; and

4. Advise customers when it appears that leaks exist on the customers’ side of the meter.

Water Savings Assumptions

In the case of purveyors who do not have existing programs, substantial savings can accrue from implementing this practice. In the South Central Texas Region some purveyors have shown water loss rates upward of 30 percent prior to implementing System Water Audit and Leak Detection and Repair programs.

Conservation Practice 2: Metering of All New Connections and Retrofit of Existing Connections

Description

Metering of all connections within a service area is an effective method of accounting for all water usage and is essential to a sound water management program. Under this conservation practice, the purveyor needs to meter all new connections within the service area and needs to develop and implement a program to retrofit all existing unmetered accounts within the service area.

Many Industrial, Commercial and Institutional (ICI) accounts use significant amounts of water for landscape irrigation. Unless these accounts have dedicated landscape meters, it is difficult to track and control landscape water usage. For this reason, the purveyor needs to determine the feasibility of retrofitting mixed-use ICI meters with dedicated landscape meters. If it is determined that retrofitting is a feasible method of reducing landscape water usage, the purveyor needs to develop a plan to retrofit mixed-use meters, either through incentive programs or mandates.

Many multi-family and ICI accounts require large meters that cannot measure water usage during low-flow periods. In order to account for all water usage for large users, the purveyor should determine the feasibility of retrofitting multi-family and ICI accounts with compound meters or similar technology.

Coverage Prerequisites

To realize this practice, the purveyor needs to accomplish the following:

20. Install meters on all new connections;

21. Within 1 year of implementation date, develop a plan to retrofit existing unmetered connections;

22. Within 1 year of implementation date, determine the feasibility of retrofitting mixed-use ICI meters with dedicated irrigation meters; and

23. By March 31, 2007, install meters on 100 percent of existing unmetered connections.

Water Savings Assumptions

Assume meter retrofits will result in a 20 percent reduction in demand by retrofitted accounts.

Conservation Practice 3: Water Waste Prohibition

Description

Water Waste Prohibition measures are enforceable actions intended to prohibit specific wasteful activities. Under this practice, the purveyor needs to enact and enforce ordinances to prohibit wasteful activities including: gutter flooding, landscape watering by sprinkler system between the hours of 10:00 a.m. and 8:00 p.m., single pass cooling systems in new connections, non-recirculating systems in new conveyer car washes, non-recirculating systems in new commercial laundry systems, non-recycling decorative water fountains, and other wasteful activities.

Coverage Prerequisites

To realize this practice, the purveyor needs to adopt and enforce water waste prohibitions consistent with the description above.

Water Savings Assumptions

Not quantified. Water savings will depend on previous ordinances and local practices. If available, provide calculated water savings and calculation methodology.

Municipal Conservation Practice 4: Conservation Pricing

Description

Conservation Pricing is a method of encouraging efficient water use through quantity-based pricing structures. In order to provide economic incentives for efficient water use, the purveyor must bill by metered volume of use. Conservation pricing provides incentives to customers to reduce average or peak use, or both. Such pricing includes: rates designed to recover the cost of providing service and billing for water and sewer service based on metered water use.

Conservation pricing is also characterized by one or more of the following components: rates in which the unit rate is constant regardless of the quantity used (uniform rates) or increases as the quantity used increases (increasing block rates); seasonal rates or excess-use surcharges to reduce peak demands during summer months; and rates based upon the long-run marginal cost or the cost of adding the next unit of capacity to the system.

For purveyors supplying both water and sewer service, this Practice applies to pricing of both water and sewer service. Purveyors that supply water but not sewer service need to make good faith efforts to work with sewer agencies so that those sewer agencies adopt conservation pricing for sewer service.

Adoption of lifeline rates for low-income customers will neither qualify nor disqualify a rate structure as meeting the requirements of this Practice.

Coverage Requirements

Purveyors need to maintain rate structure consistent with this Practice's definition of conservation pricing.

Water Savings Assumptions

Studies done within the region have shown a price elasticity of approximately -0.20. This means that for every 10 percent increase in water prices a resulting 2.0 percent reduction in water use may be anticipated. Increase in average income must be factored in by the utility to determine the actual net impact on consumer perception and response to price. For planning purposes this number may be used.

Source: Whitcomb, J., Stratus Consulting, 1999.

Conservation Practice 5: Public Information Programs

Description

Public Information Programs are effective methods of promoting water conservation and informing the public of the necessity to use water efficiently. Under this practice, the purveyor needs to establish and maintain an active public information program to educate and inform the public about water conservation.

An effective public information program should include, but is not limited to: providing speakers to employees, community groups, and the media; using paid and public service advertising; using bill inserts; providing individualized trend and comparison information on bills; and providing informational pamphlets, flyers, and manuals. In order to maximize available resources, the purveyor should coordinate with government agencies, industry groups, public interest groups, and the media.

The purveyor may realize this practice by employing resources available through the Edwards Aquifer Authority, Texas Water Development Board, or Texas Natural Resource Conservation Commission.

Coverage Prerequisites

To accomplish this practice, the purveyor needs to realize the following:

Establish and maintain an active public information program to promote and educate customers about water conservation.

Water Savings Assumptions

Not quantified. If available, provide calculated water savings and calculation methodology.

Conservation Practices 6: School Education Programs

Description

School Education Programs are a proven and widely accepted method of achieving water conservation. Under this practice, the purveyor should establish and maintain an active school education program to inform and educate students within the service area of the importance of efficient water use.

An effective school education program should include, but is not limited to: classroom presentations, instructional assistance, and distribution of educational materials. Grade-appropriate materials and presentations should be available for grade levels K-12. The purveyor is encouraged to coordinate with government agencies, industry groups, public interest groups, and the media to maximize available educational resources. Education materials should meet the state education framework requirements. Some programs, such as the “Learning to Be Water Wise and Energy Efficient” program described below, also include retrofit kits for use in the home.

Coverage Prerequisites

To realize this practice, the purveyor should accomplish the following:

Establish and maintain an active school education program to educate students in the service areas about water conservation and efficient water usage.

To accomplish this practice the following documentation will assist the purveyor:

1. Number of school presentations made annually;

2. Number and grade level of students reached;

3. Number of in-service presentations or teacher's workshops conducted annually;

4. Number of teachers reached;

5. Number and type of curriculum materials developed or provided by the purveyor; and

6. Estimated water savings achieved through school education programs.

Water Savings Assumptions

Not quantified. If available, purveyors should attempt to calculate water savings and costs. The exact methods and content of programs will affect the final water savings obtained.

One successfully implemented program where water savings have been quantified in Texas was the Harris-Galveston, Texas, collaboration with schools and private partners to distribute conservation kits to sixth-grade students using the “Learning to Be Water Wise and Energy Efficient” curriculum. At a cost of $31 per kit, water savings were calculated at an average of 1,400 gallons per month per household over a 10-year period.[1]

Conservation Practice 7: Water Survey Programs for Single-Family and Multi-Family Residential Customers

Description

Water survey programs are an effective method of tracking and controlling water usage in the single-family and multi-family residential sector. Under this practice, the purveyor needs to develop and implement a plan to market water-use surveys to single-family and multi-family residential customers.

At a minimum the survey needs to include: meter checks; leak checks for toilets and faucets; determination of flow rates for showerheads, aerators, and toilets; irrigation system and timer checks; and review or development of irrigation schedules. Residential water-use surveys should also include measurement of currently landscaped and total irrigable areas. The purveyor needs to provide the customer with an information packet including evaluation results and water saving recommendations.

Purveyors should include water softener checks in residential water surveys and should distribute information about demand-initiated regenerating (DIR) and exchange-type water softeners to encourage replacement of the less efficient timer models.

Residential Plumbing Retrofit Programs

A related method of reducing residential water use is plumbing retrofits. Under this practice, the purveyor should identify single-family and multi-family residences constructed prior to 1992, and develop a plan to distribute or directly install high-quality, low-flow plumbing devices as needed. High-quality, low-flow plumbing devices include: showerheads rated at 2.5 gallons per minute (gpm) or less, faucet aerators rated at 2.2 gpm or less, toilet displacement devices, and toilet flappers. The purveyor needs to maintain the distribution or installation programs to achieve retrofits on at least 10 percent of single-family residences and 10 percent of multi-family residences each reporting period.

The purveyor may meet the prerequisites of this practice through enforceable ordinances requiring replacement of inefficient plumbing fixtures.

Coverage Prerequisites

To realize this practice, the purveyor needs to accomplish the following:

1. Within 1 year of implementation date, develop and implement a plan to market water-use surveys to single-family and multi-family residential customers;

2. Within 10 years of implementation, contact and offer water-use surveys to all single-family and multi-family residential customers;

3. Within 10 years of implementation, complete water-use surveys for at least 15 percent of single-family residential accounts; and

4. Within 10 years of implementation, complete water-use surveys for at least 15 percent of multi-family residential accounts.

Water Savings Assumptions

Calculate water savings as follows:

Water Savings = Device Savings * Number of Devices * Probability of Installation

Where:

Device Savings may be found in the Retrofit Device Savings table.

Probability of Installation may be determined by the purveyor using the following guidelines or may be determined independently by the purveyor.

a. 100 percent for retrofits resulting from surveys conducted by the purveyor

b. 80 percent for retrofits resulting from customer requests for survey kits

c. 50 percent for retrofits resulting from survey kit distribution at public events

d. Survey follow-ups increase the probability of installation.

Retrofit Device Savings Table

Device	Initial Savings (gpd per device)	Device Life Span
Low Flow Showerheads	5.5 gpd	3 to 7 years
Toilet Displacement Devices	4 gpd	2 to 5 years
Faucet Aerators	1.5 gpd	1 to 3 years
Toilet Leak Detection	.64 gpd (8 gpd per repaired leaking toilet; 8 percent of toilets leaking)*	7 to 10 years
Other Household Leak Check	.5 gpd (12.4 gpd per household repair; 4 percent of households with leaks)	7 to 10 years
Turf Survey	12.2 gpd	4 years
Turf Survey with Timer	25.9 gpd (12.2 gpd for turf audit plus 14.7 if timer)	4 years
Source	Field Studies	Judgement
* Municipal purveyors that implement conservation programs with household leak repairs are recommended to update these calculations at their earliest convenience as water hardness and age of device will have direct impacts on these rates. Source: A&N Technical Services, Inc, 1999.

Conservation Practice 8: Residential ULFT Replacement Programs

Description

Ultra-low-flush toilet (ULFT) replacement programs are an effective method of achieving conservation in the residential sector. Under this practice, the purveyor needs to develop and implement a program to replace existing high-water-using toilets with ULFTs in single-family and multi-family residences. ULFTs are toilets that use 1.6 gallons per flush or less.

The purveyor's ULFT replacement programs need to be at least as effective as ordinances requiring toilet replacement at the time of resale.

Purveyors should consider supplementing ULFT replacement programs with ordinances that require ULFT replacement at the time of resale.

Coverage Prerequisites

To receive credit for this practice, the purveyor needs to accomplish the following:

Develop and implement a program to replace existing high-water-using toilets with ULFTs in single-family and multi-family residences.

Water Savings Assumptions

Calculate water savings as follows:

For single-family dwellings:

Water Savings = [6.693 * Persons per Dwelling - 0.529 * (Persons per Dwelling)2 + 7.826] * 365 * Number of Toilets

Water Savings = [29.9 * Number of First Toilets Replaced + 20.6 * Number of Second Toilets Replaced + 19.1 * Number of third (or higher) Toilets Replaced] * 365

For multi-family dwellings:

Water Savings = [19.138 * Persons per Unit - 0.942 * (Persons per Unit)2 + 2.181] * 365 * Number of Toilets

Water Savings = [44 * Number of First Toilets Replaced + 34 * Number of Second Toilets Replaced] *365

Where: Water Savings = Gallons per Year

Source: A&N Technical Services, Inc., 1999.

Conservation Practice 9: High-Efficiency Washing Machine Rebate Programs

Description

High-efficiency washing machines are an effective method of achieving conservation in the residential sector. Under this practice, the purveyor needs to offer cost-effective financial incentives to encourage the purchase and use of high-efficiency washing machines. Incentive levels may be calculated using methods found in A Guide to Customer Incentives for Water Conservation, prepared by Barakat and Chamberlain (February 1994).

Incentives and rebates may be offered in conjunction with rebate programs sponsored by local energy providers.

Coverage Prerequisites

To realize this practice, the purveyor needs to accomplish the following:

Provide cost-effective customer incentives for the purchase of high-efficiency washing machines.

Water Savings Assumptions

Calculate water savings as follows:

For single-family machines:

Water Savings = Savings per Load * Water use per Load * Loads per Person * Persons per Household * 365 * Number of Machines

For multi-family machines:

Water Savings = Savings per Load * Water use per Load * Loads per Person * Persons per Household * Units per Machine * 365 * Number of Machines

Where: Water Savings = Gallons per Year

Savings per Load = 37.8 percent

Water Use per Load = 48.5 Gallons

Loads per Person = 0.45

Source: A&N Technical Services, Inc., 1999.

Conservation Practice 10: Hot Water on Demand Systems

Description

Hot water on demand systems deliver hot water at the showerhead or faucet without draining cold water from the pipes between the fixture and the water heater. This is accomplished by either a valve and pump to recirculate cold water to the water heater, or by using a instantaneous heater located near the fixture of interest. In the valve and pump system, the recirculating pump stops and the valve closes when a temperature sensor measures the arrival of hot water from the heater.

Factors that influence savings include the distance between the water heater and the fixtures, and pipe location and insulation (pipes are often uninsulated and in attics or under a pier and beam foundation). Most of these devices are targeted for the single-family residential sector, although the ICI and multi-family sectors have potential.

Some communities have taken the approach of requiring installation of recirculating hot water systems similar to those used in the commercial sector in new houses.

Coverage Prerequisites

To accomplish this practice, the purveyor needs to achieve the following:

1. Establish and maintain an active public information program to promote and educate customers about hot water on demand systems;

2. Identify average distance from hot water heater to shower in local homes or businesses;

3. Determine the benefits of a hot water on demand systems for average home or business, and develop incentives for existing customers to retrofit; or

4. Where pertinent an ordinance requiring installation of hot water on demand systems in new construction.

Water Savings Assumptions

Savings Calculation (gpd/hot water demand unit):

Water Savings = Cold Start Hot Water Runs * Savings per Run * Plumbing

Where: Cold Start Hot Water Runs = PPH * Hot Water Runs * Scale Factor

Savings per Run: Mean: 4.0 gallons per hot water run; Range: 2 to 12 gallons per run

Hot Water Runs: Mean: 6 hot water runs per day per person; Range: 2 to 10

Scale Factor: .8

PPH: Persons per household—single-family

Plumbing: .75 Plumbing system factor assumes half of houses realize only half savings.

Source: A&N Technical Services, Inc., 1995; CEC, 1995.

The savings figures are for retrofits. The savings estimates may be underestimated because they do not account for all behavioral components. For example, many people tend to warm up their water beyond what is necessary (e.g., until it "steams").

Conservation Practices 11: Conservation Programs for Industrial, Commercial, and Institutional Accounts

Description

Conservation programs for industrial, commercial, and institutional (ICI) accounts are essential for reducing water usage in the ICI sector. Under this practice, the purveyor needs to identify industrial, commercial, and institutional customers and rank them according to water usage.

To accurately track water usage by ICI accounts, the purveyor needs to develop and market an ICI water-use survey and customer incentives program. Directly contact (via letter, telephone, or personal visit) and offer water use surveys and customer incentives to at least 10 percent of commercial, industrial, and institutional accounts on a repeating basis. A water use survey needs to include: a site visit; an evaluation of all water-using equipment and processes; a report identifying recommended conservation measures and their expected payback; and available agency incentives. The purveyor should conduct annual follow-up visits to evaluate the status of recommended water-saving improvements.

In lieu of the water-use survey and customer incentives program, the purveyor may choose to implement other programs to reduce water usage in the ICI sector. The purveyor may reduce ICI water usage through rebates for equipment replacement, perform workshops targeted to specific sectors of their ICI base, or provide other incentives for new and established businesses to improve their water efficiency.

Providing educational materials for visitors to South Central Texas through commercial hospitality industry, such as optional laundry services in hotels/motels, is one innovative example of public/private partnerships for water conservation in San Antonio. Incentives for commercial and industrial users who can recycle water internally can also lead to significant water savings. On-site water recycling systems require proper plumbing and treatment equipment. Retrofits of existing and construction of new car washes or other industrial uses in San Antonio have shown recycling capabilities of 60 to 90 percent.

For purposes of this practice, commercial, industrial, and institutional customers are defined as follows:

A. Commercial Customers: any water user that provides or distributes a product or service, such as hotels, restaurants, office buildings, commercial businesses, or other places of commerce. These do not include multi-family residences, agricultural users, or customers that fall within the industrial or institutional classifications.

B. Institutional Customers: any water-using establishment dedicated to public service. This includes schools, courts, churches, hospitals, and government facilities. All facilities serving these functions are to be considered institutions regardless of ownership.

C. Industrial Customers: any water users that are primarily manufacturers or processors of materials as defined by the Standard Industrial Classifications (SIC) Code numbers 2000 through 3999.

Coverage Prerequisites

To realize this practice, the purveyor needs to accomplish the following:

1. Identify industrial, commercial, and institutional accounts and rank them by water use;

2. Within 10 years of initiation, contact and offer water-use surveys and/or customer incentives to 100 percent of ICI accounts;

3. Within 10 years of initiation, complete water-use surveys for 10 percent of ICI accounts; and

4. If utilizing other programs in lieu of the water-use survey and customer incentives program: within 10 years of initiation, reduce ICI water usage by 10 percent of baseline ICI usage.

Water Savings Assumptions

Calculate water savings as follows:

Water Savings = Number of Surveys * Estimated Savings * Water Used

Where: Estimated Savings = 18 percent or percentage determined through survey results

Water Used = Average (5 years) annual water use by ICI customers receiving the survey

Source: A&N Technical Services, Inc., 1999.

For purveyors considering a ULFT replacement or retrofit program for ICI customers the following table will assist in calculating estimated water savings by market segment.

Savings per ICI ULFT Installed

Market Segment	Estimated Savings (gpd)	90 percent Confidence Interval
Wholesale	57	19-94
Food Store	48	37-59
Restaurant	47	36-58
Retail	37	33-42
Automotive	36	22-50
Multiple Use	29	14-45
Religious	28	20-37
Manufacturing	23	15-32
Health Care	21	13-28
Office	20	17-23
Miscellaneous	17	11-23
Hotel/Motel	16	11-20
Source: Hagler Bailly Services, 1997.

ICI Conservation Practice 12: Cooling Water Recirculation

The use of water for cooling towers in industrial and commercial applications represents a significant water use in the South Central Texas. Water is typically used to cool heat‑generating equipment or to condense gases in a thermodynamic cycle. Single-pass cooling is the most water‑intensive cooling method used in industrial applications. Water contacts a heat source, lowers its temperature, and then is discharged.

Recycling water within a recirculating cooling system can greatly reduce water use by using the same water to perform several cooling operations. The EPA notes that the water savings are sufficiently substantial to result in overall cost savings to the industry.[2] Three cooling water conservation approaches that can be used to reduce water use are evaporative cooling, ozonation, and air heat exchange (Brown and Caldwell, 1990).

In industrial/commercial evaporative cooling systems, water loses heat when a portion of it is evaporated. Evaporation, drift, and blowdown result in substantial water loss from evaporative cooling towers. (Blowdown is a process in which some of the poor‑quality recirculating water is discharged from the tower in order to reduce the total dissolved solids and protect the equipment from corrosion.) Water savings associated with the use of evaporative cooling towers can be increased by treating the water to reduce blowdown or water discharges from cooling towers.

Air heat exchange works on the same principle as a car's radiator. In an air heat exchanger, a fan blows air past finned tubes carrying the recirculating cooling water. Air heat exchangers involve no water loss, but they can be relatively expensive when compared with cooling towers (Brown and Caldwell, 1990).

Coverage Prerequisites

To realize this practice, the purveyor needs to accomplish the following:

1. Identify industrial, commercial, and institutional accounts with significant water use for cooling;

2. Within 10 years of initiation, contact and offer water-use surveys and/or customer incentives to 100 percent of these ICI accounts;

3. Within 10 years of initiation, complete water-use surveys for 10 percent of ICI accounts; and

4. If utilizing other programs in lieu of the water-use survey and customer incentives program: within 10 years of initiation, reduce ICI water usage by 10 percent of baseline ICI cooling water usage.

Water Savings Assumptions

Steam generating plants have shown ten-fold reductions in water use by converting from water heat exchangers to air heat exchangers. The higher cost of operating an air heat exchanger may provide a disincentive to such conversions. Industrial, commercial and institutional consumers may save significant amounts of water by moving from single-pass cooling to multiple cycles through use of chemical or ozone treatment systems.

The use of ozone to treat cooling water (ozonation) can result in a five‑fold reduction in blowdown when compared to traditional chemical treatments and should be considered as an option for increasing water savings in a cooling tower (Brown and Caldwell, 1990).

A simple formula for estimating potential savings is:

Water Savings = (evap loss in gpm/(cycles of concentration after conversion‑ 1)) - (evap loss in gpm/(cycles of concentration before conversion - 1))

Where: evap loss in gpm = 30 gpm evaporation is standard for a 1,000 ton cooling tower

Source: San Antonio Water System Conservation Department, 2000.

Conservation Practices 13: Landscape Conservation Programs and Incentives

Description

Landscape conservation programs are an effective method of accounting for and reducing outdoor water usage. Under this practice, the purveyor should provide non-residential customers with customer support, education, incentives, and assistance in improving their landscape water use efficiency. To increase the cost-effectiveness of these programs many purveyors target customers with large landscapes.

The purveyor should identify accounts with dedicated irrigation meters and assign PET-based water use budgets equal to no more than 100 percent of the potential evapotranspiration of turfgrass per square foot of landscape area.[3] For accounts with water-use budgets, the purveyor should provide notices each billing cycle showing the relationship between budgeted water usage and actual consumption.

The purveyor should develop and implement a plan to market large landscape water-use surveys to Industrial, Commercial and Institutional (ICI) accounts with mixed-use meters. At a minimum the water-use surveys should include: measurement of the landscape area; measurement of the total irrigable area; irrigation system checks and distribution uniformity analysis; review of irrigation schedules or development of schedules as appropriate; provision of a customer survey report and information packet. When cost-effective, the purveyor should offer the following: landscape water-use analyses and surveys; voluntary water-use budgets; installation of dedicated landscape meters; and follow-up to water-use analyses and surveys. Similar services can be extended to residential customers.

The San Antonio Water System offers rebates to customers who install xeriscape landscaping in place of turfgrass. Xeriscape plants are typically lower water users than turfgrass and are better adapted to long periods without rainfall. Greywater reuse systems are another innovative means of supplementing or replacing potable irrigation water for landscape irrigation. Proper filtration is required on greywater reuse systems.

For new customers and change-of-service customer accounts, the purveyor should provide information on landscape design appropriate to the climate and efficient irrigation equipment and management. The purveyor should install water-efficient landscaping appropriate to the climate at water-agency facilities and install landscape meters where appropriate. Ordinances requiring minimum design standards for efficient irrigation systems is another potential approach.

When cost-effective, the purveyor should consider offering the following services:

1. Training in landscape maintenance and irrigation system design;

2. Financial incentives (such as loans, rebates, and grants) to improve irrigation system e