BMP #13 - Other Water Use

Background

Many other high water using processes are found at federal facilities including vehicle wash systems, maintenance facilities, cleaning/laundry services, single pass air conditioners, water softening systems, and others. You should identify and analyze all high-water using processes for potential water and energy efficiency improvements.

Laundry facilities are often found at federal facilities. The laundry facility may be a self-serve laundry where residents and personnel wash their own clothing, a commercial-type laundry service where residents drop off laundry to be washed or dry cleaned, or it may be an industrial laundry facility where large volumes of government-owned linens and uniforms are cleaned. Large amounts of water are regularly used in industrial laundries, making them highly suitable for a water efficiency program.

Evaporative coolers, also known as swamp coolers and desert coolers, work on the same principle as cooling towers. Air is cooled and humidified as it passes through porous pads that are kept moist by water dripped on their upper edges. Unevaporated water trickles down through pads and collects in a pan for either discharge or recirculation. Since the cooling relies on evaporation, these coolers work best in arid climates. When water evaporates it leaves behind scale and mineral deposits on the pads. This reduces the volume of air flowing through the pads and compromises the performance of the cooler. Bleed-off water serves to dilute the mineral concentration of pan water and reduces scale and dirt build-up on the pads. There are two types of bleed-off systems: once-through and recirculating. The once-through or pumpless type is simpler and less expensive than the recirculating or pump type, but it consumes more water and requires constant drainage.

In many areas of the country additional water softening should not be necessary for most operations. When water softeners are required, look for systems that generate a minimal amount of waste brine per gallon of water softened.

The military maintains facilities for washing and rinsing its aircraft and vehicles. These washrack facilities encompass aircraft, wheeled vehicles, and truck vehicles such as tanks and are an excellent candidate for water efficiency. There are five typical washrack groups based on the type of wastewater emitted: aircraft rinsing, aircraft washrack platform, automotive vehicle washrack, tracked vehicle washrack, and automotive vehicle maintenance. The amount of water used per item washed varies from about 100 to 3,000 gallons. Newer, commercially available washrack equipment will usually include some retrofit and recycling options that can significantly reduce the amount of water used per item washed.

Get expert advice to help determine if water efficiency improvements of the other high water using processes are appropriate. New system designs and improved materials can significantly reduce the water and energy requirements. However, since this may involve significant capital costs, the facility manager should investigate every retrofit or O&M option first. Your first resource should be your local or higher headquarters engineers, but do not overlook or rule out the benefits of input from experienced contractors or other Governmental agencies (DOE, FEMP, etc.)

For more information on this and other FEMP Water Efficiency Best Management Practices, please see the resources section.

Operation and Maintenance Options

If practical, consider metering or otherwise measuring the amount of water used in other high water using processes.
As with all water-using equipment, locate and repair leaks in plumbing connections.
If applicable, ensure that procedures are in place to turn off the water supply when the equipment is not in operation. Some equipment allows water to constantly run, even when the equipment is turned off.
If applicable, check flow rates to ensure they are within manufacturers' recommendations. For maximum water savings the flow rate should be near the minimum allowed by the manufacturer. This can produce significant water savings.
To reduce water used by evaporative coolers, keep a tight rein on the amount of bleed-off water. For most small coolers, bleed-off volumes should be less than a few gallons per hour for each 1,000 cubic feet per minute of air flow. Also, replace worn or torn pads and inspect the recirculation pump and reservoir level controls periodically during the warm months when the system is running.
For water softeners, set the softener controls to start the softening and regeneration process only when needed. Softeners with timers should be avoided.
For existing washing machines, encourage users to wash only full loads. If the water level is able to be set by the user, encourage using only as much water as needed for that load. Also consider separating laundry by cycles needed.
Large commercial laundry equipment should be easily programmable to use no more water than is required for the degree of soiling of the items being washed.
For washrack cleaning facilities that use detergents, use high quality detergents to shorten the length of time required to clean each vehicle or aircraft.

Retrofit and Replacement Options

If applicable, replace water-cooled equipment with air-cooled equipment, or the best available technology for achieving energy and water efficiency.
Avoid single-pass or pumpless coolers. Recirculation saves water and increases the thermal efficiency.
New water softener models may come with water-efficient regeneration cycles.
For existing washrack cleaning facilities, there are several low cost measures that are capable of saving significant amounts of water. Timers and automatic spray heads are useful in aircraft rinsing facilities, but not for washrack units since each vehicle or aircraft must be washed until sufficiently clean. Automatic shutoff nozzles are designed for facilities with manual rinsing. Since water is usually left on during the entire time a vehicle or aircraft is washed and rinsed, the automatic shutoff spray nozzle can save tens to hundreds of gallons per run. Low flow and high pressure hot water units can reduce the amount of water and solvents used by facilities for cleaning engine components. Pre-wash areas are recommended for tracked vehicle washracks with recycling systems, to eliminate a majority of the coarse dirt so that it will not enter into and clog up the treatment system. Where feasible, include water reuse equipment on vehicle washing equipment. Also consider using self-closing valves on chamois wringers.
For washrack cleaning facilities, choose new rollover and conveyor equipment that uses less than 35 gallons per vehicle for automobiles and light trucks and less than 75 gallons per vehicle for bus and large truck washes.
The costliest, but most highly effective way to reduce water usage at wash and rinse facilities is to implement a wastewater recycling system (see BMP #14). Where possible reuse reverse osmosis or nanofiltration reject water for vehicle washing in rollover and conveyor type systems.
Replace old commercial clothes washers (vertical axis) with new high efficiency washers (horizontal axis) that use significantly less energy, water, and detergent. Look for ENERGY STAR® labeled washers with a water factor of 8.5 gallons of water used per cubic foot or less. Most full-sized ENERGY STAR qualified washers use 18-25 gallons of water per load, compared to the 40 gallons used by a standard machine. These efficient washers have the potential to reduce combined utility costs by as much as 50 percent.
For large industrial or commercial type laundries, consider replacing old washers with tunnel washers, or ozone laundering. Tunnel washers, also known as continuous batch washers, are heavy-duty, multi-tank systems for use in large industrial laundries. They are capable of handling up to 2,000 pounds of laundry per hour. Tunnel washers use counter current wash methods to maximize water efficiency. These are costly to install, but are capable of saving up to 70 percent of the volume of water used with a washer-extractor, and require less operating and maintenance labor. Tunnel washers typically use about 2 gallons or less per pound of laundry.
Technologies for reducing water use in laundry operations include ozone laundering. Ozone laundering is suited for lightly to moderately soiled laundry and uses no detergent, uses only cold water, and recycles water. Ozone-generating equipment is attached to the washer as a closed-loop system.

Additional Resources

Air Force Civil Engineer Support Agency. Air Force Water Conservation Guidebook, May 2002.

General Services Administration. Water Management: A Comprehensive Approach for Facility Managers.

Military Handbook: Water Conservation. MIL-HDBK-1165. April 1997.

New Mexico Office of the State Engineer. A Water Conservation Guide for Commercial, Institutional and Industrial Users. July 1999.