Water Conservation Guidelines, Principles, and Best Practices

  

Water Conservation Guidelines, Principles, and Best Practices

     Using water efficiently has many benefits including better water quality, improving aquatic ecosystems, and mitigating drought. Amendments to the Safe Drinking Water Act in 1996 required EPA to develop water conservation guidelines for water utilities. The guidelines are at the discretion of the states and are considered to be voluntary. Guidelines are given for public water systems of three different sizes. The basic guidelines are for those that serve a population of 10,000 or fewer. The intermediate guidelines are for those that serve populations between 10,000 and 100,000. The advanced guidelines are for those that serve populations of 100,000 or more. A three-level structure is given for conservation recommendations as shown below. Level 1 measures are for Basic guidelines and Levels 2 and 3 are added for Intermediate and Advanced guidelines.

Level 1 Measures

* Universal metering

* Water accounting and loss control

* Costing and pricing

* Information and education

Level 2 Measures

* Water-use audits

* Retrofits

* Pressure management

* Landscape efficiency

Level 3 Measures

* Replacements and promotions

* Reuse and recycling

* Water-use regulation

* Integrated resource management

     Universal metering is the first Level 1 measure. Metering is a key tool in water resource management. Source-water metering and service-connection metering are the main ways water is metered. For accurate comparisons and accounting, source-water and service-connection meters should be read at the same relative time. There is also public-use metering where water is available for public use. Meters should be read at regular fixed intervals, usually monthly. Water meters can be damaged and get less accurate as they age. They should be tested, calibrated, repaired, or replaced as needed.  

 

     Water accounting and loss control especially includes what is called nonaccount water which refers to both water that is metered but not billed as well as all unmetered water. Where nonaccount water is high, there are likely to be issues such as leaks, unauthorized use, or water used for utility operation and maintenance purposes. Other issues like inaccurate controls, bad meters, and accounting errors can also contribute to nonaccount water volumes. Mitigation strategies include better system analysis and audits, a leak detection and repair strategy, automated sensors/telemetry, and a loss prevention program.

 

Regarding a leak detection and repair strategy EPA notes:

 

“This strategy may include regular on-site testing using computer-assisted leak detection equipment, a sonic leak-detection survey, or another acceptable method for detecting leaks along water distribution mains, valves, services, and meters. Divers can be used to inspect and clean storage tank interiors.”

 

Remote sensors and corresponding monitoring software can alert operators to leaks, changes in pressure, problems with equipment integrity, and more. A loss-prevention program could include pipe inspection, cleaning, lining, and minimizing water use during system maintenance.

    

     Costing and pricing are considered to be a water conservation measure because they are based on usage and the costs of delivering the water and operating and maintaining the public water system to settle at a fair price that can be agreed upon. EPA recommends ‘cost-of-service accounting,’ metered rates so that one pays more for higher usage (cost-based pricing), and cost analysis in order to understand seasonal usage patterns and non-promotional rates. The latter seems to refer to keeping prices high so that water conservation is incentivized over water use. That sounds fine in theory, but we ratepayers do not get the benefit of the doubt. They are also referring to things different rates for different classes of users, seasonal rates, and the common minimum bills where one pays the minimum even though one may only use half or less of that minimum. The effects of pricing on revenue should be analyzed as well.

 

“Conservation-oriented pricing requires planners to make certain assumptions (based on the available empirical evidence) about the elasticity of water demand, or the responsiveness of water usage to a change in price. Elasticity is measured by the ratio of a percentage change in quantity demanded to a percentage change in price. Changes in the rate structure should allow the system to achieve demand reduction goals recovering water system costs. In allocating costs, the impact of the rate structure on user demand and revenues for specific customer classes should be considered.”

 

Advanced pricing methods consider these elasticity factors, seasonal demand, type of water, and class of user to arrive at prices that optimize conservation.

     Information and education are critical to the success of any conservation program. They can change water-use habits. Understandable and informative water bills with comparisons to previous bills and tips on water conservation can be helpful in changing consumption behavior. Educational events can help teach about water conservation.

Level 2 measures (for public water systems that serve between 10,000 and 100,000) include water use audits, retrofits, pressure management, and landscape efficiency.

     Water use audits are typically useful for large-volume commercial and industrial water users. Process, sanitary, domestic, heating, cooling, outdoor, and other water uses may be included. The goal is to find areas where water use can be reduced. Large-landscape audits usually refer to irrigation water use. The use of irrigation submeters may be useful in conducting these audits and increasing the efficiency of water use is the goal. Selective end-use audits can find areas where water is being wasted or where there are significant plumbing leaks.

 

     Retrofits involve improving existing fixtures or appliances instead of replacing them in order to increase water-use efficiency. Retrofit programs usually target plumbing fixtures and retrofit kits may include low-flow faucet aerators, low-flow showerheads, leak detection tablets, and replacement flapper valves. Retrofit programs may target residential, commercial, industrial, public buildings, and other sectors.

 

     Pressure management can be very useful for reducing water use. Pressure reduction can decrease leaked volumes and the excessive flow that can increase waste. Lower water pressure can also increase component life by decreasing the pressure stress on those components. It can also extend the life of end-use fixtures and appliances.   

“Systemwide pressure management. For residential areas, pressures exceeding 80 psi should be assessed for reduction. Pressure management and reduction strategies must be consistent with state and local regulations and standards, as well as take into account system conditions and needs. Obviously, reductions in pressure should not compromise the integrity of the water system or service quality for customers.”

“Pressure-reducing valves. A more aggressive plan may include the purchase and installation of pressure-reducing valves in street mains, as well as individual buildings. Utilities might also insert flow restrictors on services at the meter. Restrictors can be sized to allow for service length, system pressure, and site elevation. Utilities can consider providing technical assistance to customers to address their pressure problems and install pressure-reducing valves to lower the customers’ water pressure. This may be especially beneficial for large-use customers.”

     Landscape efficiency is simply reducing outdoor water use. Irrigation for agriculture as well as for public parks, building grounds, nurseries, garden centers, and golf courses is targeted for efficiency improvement. Xeriscaping is one method of reducing water use that utilizes planning and design, limiting turf areas, efficient irrigation, soil improvement, mulching, the use of lower water demand plants, and appropriate maintenance.

“Irrigation management. Irrigation management systems, using metering, timing, and water-sensing devices, also can be promoted by the water utility for large-volume customers.”

     Level 3 measures (for utilities serving over 100,000 customers) include replacements and promotions, reuse and recycling, water-use regulation, and integrated resource management.

     Replacements and promotions involve rebates, incentives, and promotions of new technologies. Rebates and incentives can accelerate the replacement of older fixtures. Utilities can provide free replacement, rebates, or other cost-reduction mechanisms. They can be targeted to residential, commercial, or industrial users. Higher efficiency standards can be adopted into state and local plumbing codes to accelerate the upgrades. Promotions of new technologies by manufacturers and distributors can speed adoption and reduce water use. High-efficiency and low-water use washing machines, toilets, faucets, and more are examples.

     Reuse and recycling are mostly targeted to industrial and large-volume irrigation customers. Treated ‘gray water’ can be reused. Some manufacturing processes can utilize recycled water. This wastewater can also be reused for some industrial purposes, agricultural purposes, groundwater recharge, and direct reuse. Irrigation water runoff can be collected and reused. Selective residential applications of reuse and recycling can be pursued as well.  

     Water-use regulation may include water-use regs and standards, particularly for managing water during times of drought or other water supply concerns. Emergency or non-emergency measures may be adopted. Examples include restrictions on lawn watering, car washing, filling swimming pools, washing sidewalks, irrigating golf courses, commercial car washes, hotels, etc. New developments should be screened for high water use potential and can be required to be designed for water efficiency by developing reasonable standards for them.

     Integrated resource management may include supply-side or demand-side management technologies. Supply-side technology may include automation and the strategic use of water storage with the goal of achieving energy, chemical, and/or water savings. Another very important supply-side strategy is source-water protection. Managing land use practices around source water areas such as public well fields is very important for the prevention of water contamination. Demand-side technologies mostly refer to practices such as end-use audits to identify where water use can be reduced.

Efficiency, Demand, and Climate: All Impact Water Availability

     Areas subject to droughts and recurring low reservoir water levels are more vulnerable to water waste and can benefit more from conservation. Groundwater availability is another factor. Water utilities often must decide whether to expand their systems due to increasing demand or to increase efficiency and conservation measures instead. EPA published a book in 2016 to address this issue. It is titled ‘Best Practices to Consider When Evaluating Water Conservation and Efficiency as an Alternative for Water Supply Expansion.’ California, with its history of droughts, water supply restrictions, very high agricultural use, and its dependency on climate, including snowpack replenishment on water supply, is a major ongoing case study for water conservation.

     The book goes into detail about both supply-side and demand-side management and accounting. Leak management, metering, conservation pricing, and conservation planning and analysis are all covered. Water demand forecasting, aquifer stress, leakage rates, total water loss rates, and opportunities to reduce water use are all factored into water conservation planning and analysis. The graphs below are from this book.

 

 

EPA’s WaterSense Designation and Labeling

     The EPA developed a designation called WaterSense that indicates that a fixture meets the EPA’s efficiency recommendations. Toilets, showerheads, bathroom faucets, urinals, spray sprinkler bodies, pre-rinse spray valves, and irrigation controllers are examples of devices that can get the WaterSense designation.

 

Irrigation Controllers

Weather-based irrigation controllers use local weather and landscape conditions to derive watering schedules, and soil moisture-based irrigation controllers (soil moisture sensors, or SMSs) monitor moisture levels in the soil to prevent irrigation when water is not needed.

 

Pre-Rinse Spray Valves

Pre-rinse spray valves are used in restaurant kitchens to remove food from dishes before washing. They use high pressure, and their use can represent one-third of the water use of a commercial kitchen. Thus, using high-efficiency valves can save water use and money.

 

References:

 

Using Water Efficiently. U.S. EPA. Using Water Efficiently | US EPA

Best Practices to Consider When Evaluating Water Conservation and Efficiency as an Alternative for Water Supply Expansion. EPA-810-B-16-005. December 2016. Best Practices to Consider When Evaluating Water Conservation and Efficiency as an Alternative for Water Supply Expansion (epa.gov)

WaterSense. U.S. EPA. WaterSense | US EPA

Water Conservation Plan Guidelines. U.S. EPA. August 6, 1998.  Water Conservation Plan Guidelines | US EPA