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Best Management Practice #13: Other Water-Intensive Processes

Many water-intensive processes beyond the Federal Energy Management Program’s best management practices (BMPs) for water efficiency are in place at federal facilities, including laundry equipment, vehicle wash systems, evaporative coolers, and water softening systems. 

When assessing facility water use, it is important to identify and analyze all water-intensive processes for potential efficiency improvements. This BMP provides tips on water-saving operational and maintenance actions as well as retrofit and replacement options for these equipment types.

Laundry Equipment

Laundry facilities are in federal facilities that provide housing. Laundry facilities can be: 

  • Self-serve (residents and personnel wash their own clothing)
  • Commercial (residents drop off laundry to be washed or dry cleaned)
  • Industrial (large volumes of linens and uniforms are cleaned). 

There are several types of commercial laundry equipment, including:

  • Multiload washers
  • Washer extractors
  • Tunnel washers. 

For more information about these types of commercial laundry equipment, visit the U.S. Environmental Protection Agency (EPA) WaterSense at Work laundry equipment best management practice.

Operation and Maintenance
  • Regularly check for leaks and repair broken or loose connections and components.

  • Encourage users and operators to wash only full loads. If the water level can be set by the user, encourage using only as much water as needed for that load. Also consider separating laundry by the number of cycles needed.

  • Program large commercial laundry equipment to use no more water than required for the degree that the items are soiled.

  • Use detergent formulated for the type of equipment (such as high-efficiency machines should use high-efficiency detergent). This can reduce the amount of rinsing required.

Retrofit and Replacement Options
  • Consider retrofitting existing equipment to recycle the rinse water in the next wash cycle. For large commercial equipment, recycling systems can save significant water use. Consider treatment requirements and space constraints when investigating this option. 

  • Install an ozone system on existing equipment. Ozone is a powerful oxidant that disinfects laundry. Ozone is well suited for light- to moderately-soiled laundry (such as hospital and hotel linens) that requires disinfecting and whitening. Ozone systems save water by reducing rinsing requirements. Ozone reacts best in cold water, so these systems can reduce energy use as well.

  • For single-load residential and commercial clothes washers, purchase ENERGY STAR-qualified machines. 

  • For multi-load washers, purchase machines that use no more than 8.0 gallons per cubic foot of capacity.

  • For washer exactors, purchase machines that have water recycling systems, which store the previous load’s rinse water for the next load’s wash cycle.

  • When replacing old or purchasing new large industrial laundry equipment, consider tunnel washers. Also known as continuous-batch washers, tunnel washers recycle water multiple times as laundry moves through the washing and rinsing process. 

Vehicle Wash

Some federal agencies maintain facilities for washing and rinsing vehicles. This includes the military and U.S. Postal Service. These washrack facilities may be excellent candidates for water-efficiency improvements. 

There are five typical washrack groups based on the type of wastewater emitted:

  1. Aircraft rinsing
  2. Aircraft washrack platform
  3. Automotive vehicle washrack
  4. Tracked vehicle washrack
  5. Automotive vehicle maintenance.

Central vehicle wash facilities are common at military installations that wash large-wheeled and tracked tactical vehicles. These systems have large basins where vehicles are cleaned with high-pressure nozzle guns. Wastewater is sent to a settling pond and treated to remove contaminants. Treated water is then recycled back through the system to the wash basins. It is also common for military installations to have vehicle wash bays at maintenance shops where vehicles are washed by hand with an open hose or with a high-pressure washing system.

Federal facilities may also have conveyor system where vehicles are pulled through a series of sprays. Another type of vehicle washing equipment is an in-bay system where vehicles are stationary and a series of spray nozzles pass along the vehicle.

Operation and Maintenance
  • Consider submetering the washing system.

  • Periodically check for leaks in plumbing connections, and make repairs immediately.

  • If applicable, ensure procedures are in place to turn off the water supply when equipment is not in operation. Some equipment allows water to constantly run even when the equipment is turned off.

  • Check flow rates to ensure they are within manufacturer recommendations. For maximum water savings, the flow rate should be near the minimum allowed by the manufacturer.

  • Use high-quality detergents to shorten the length of time required to clean each vehicle or aircraft.

  • Make sure nozzles and sensors are calibrated and aligned properly in conveyor and in-bay systems so nozzles spray at the correct time and in the correct direction.

Retrofit and Replacement Options
  • For vehicle wash bays with open hoses for manual washing, install a high-pressure washing system that includes a hand-triggered spray nozzle. These systems have a much lower flow rate than an open hose and provide pressurized water that shortens the cleaning time. In addition, automatic shutoff nozzles can save a significant amount of water at facilities with manual rinsing since water is usually left on during the entire time a vehicle or aircraft is washed and rinsed.

  • 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 effective way to reduce water usage at wash and rinse facilities is to implement a wastewater recycling system. Ensure the system has appropriate treatment, which may require separation, filtration, and reverse osmosis.  For information on this type of system, EPA WaterSense at Work vehicle washing best management practice.

Evaporative Coolers

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 cooling relies on evaporation, these coolers work best in arid climates.

When water evaporates, it leaves behind scale and mineral deposits on the pads, reducing the volume of air flowing through the pads and compromising cooler performance. 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 consumes more water and requires constant drainage.

Operation and Maintenance
  • As with all water-using equipment, locate, and repair leaks in plumbing connections.

  • If applicable, ensure procedures are in place to turn off the water supply when equipment is not in operation. 

  • If applicable, check flow rates to ensure they are within manufacturer recommendations. For maximum water savings, the flow rate should be near the minimum allowed by the manufacturer.

  • Keep a tight rein on bleed-off water amounts. 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 warm months when the system is running.

Retrofit and Replacement Options
  • When installing new evaporative cooling equipment, look for the efficiency rating, which ranges from three to 15 gallons per ton-hour of cooling. There is no current standard for evaporative coolers, however five gallons per ton-hour of cooling is considered water-efficient. For more information, visit the Alliance for Water Efficiency website. 

Water Softeners

Water softeners are used to remove minerals such as calcium and magnesium from water. Water softeners can be used as pretreatment in water purification systems. Cooling towers and can also be used to remove minerals from hard water supply at the whole building level.

Operation and Maintenance
  • Locate and repair leaks in plumbing connections.

  • If applicable, ensure procedures are in place to turn off the water supply when equipment is not in operation. 

  • Check flow rates to ensure they are within manufacturer recommendations. For maximum water savings, the flow rate should be near the minimum allowed by the manufacturer.

  • Set the controls to start softening and regeneration processes only when needed. Softeners with timers should be avoided.

Retrofit and Replacement Options
  • Install new water softening equipment that regenerates based on the hardness of the water supply and water consumption demand.