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The City of Portland, Oregon

Portland Water Bureau

From forest to faucet, we deliver the best drinking water in the world.

Customer Service: 503-823-7770


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Car Washes

Over the last decade, professional car washes have implemented and improved water conservation practices. The measures below can help professional car washes become even more water-efficient.

Conduct a water usage survey

  • A water usage survey identifies the quantities, characteristics, and uses of water at  the site. From the water-usage survey a water balance can be created which will help the water efficiency team decide where to focus their efforts.

Process Improvements:

  • Consider reducing nozzle size – Evaluate car wash design to consider whether the system can handle a reduced nozzle size. Some systems are designed to ensure the car is thoroughly washed, rather than focusing on thoroughly washing the car in a water efficient manner. It is often possible to reduce nozzle size without impacting the quality of the wash. This measure can provide one of the most significant water reductions in the car wash process. Install lower flow nozzles and run at lower pressure; adjust flow in nozzles, sprays, and other lines to meet desired quality requirements.
  • Install a reclaimed water system – Many car washes already have reclaimed water systems. These systems are generally designed to reuse the final rinse water in the initial wash water stage. More elaborate systems will filter and reuse even more water.
  • Time arches – Precisely time the conveyor to come on as car arrives and shut off as car moves out from under the arches.
  • Adjust nozzle angle – Regularly inspect nozzles to ensure they are aligned properly. Placing nozzles that spray above and over the upper sides of vehicles will allow gravity to aid cleaning.
  • Inspect nozzle spray pattern – Regularly inspect nozzles to make sure their spray pattern is consistent. If the spray pattern is not consistent perform maintenance on the nozzle to make sure it is not clogged and is in proper operational condition. It might be necessary to replace the nozzle.
  • Replace nozzles as they become worn – As nozzles age their ability to deliver a consistent spray pattern is diminished. An inefficient spray pattern is not always visually apparent. Replace spray nozzles regularly to assure maximum efficiency. The expected life of nozzles varies based on a variety of conditions (i.e. make/model, water quality, water pressure, hours in operation, etc). Check with the nozzle manufacturer for more details.
  • Operate nozzles only when vehicles are in the spray pattern - Install equipment that turns nozzles on only when vehicles are in the spray pattern rather than operating during the entire wash cycle.
  • Regularly inspect system for leaks – Nozzles and other parts of the system can develop leaks and waste a lot of water, often as much as 10% of the total water use. Replace nozzles or other equipment that cannot be repaired.
  • Use reverse osmosis (RO) reject water for the initial wash stage or landscaping - Car washes often employ reverse osmosis to remove dissolved solids from hard water to ensure a spot-free rinse. Reject water from this process can be used in other parts of the wash although further treatment for odor and color may be desirable. In addition, it may be necessary to avoid its use in high-pressure rinses. Landscape irrigation offers another area in which RO reject water could substitute for potable water. RO reject water may not be appropriate for all plants. Check your local nursery for more information.
  • Increase dwell time for car after final rinse – Increasing the dwelling time provides a longer period to collect rinse water for the reclamation unit.
  • Evaluate towel-washing efficiency – Use high efficiency towel/rag washers and only run full loads.
  • Turn off all flows during shutdowns - Use solenoid valves to stop the flow of water when production stops
  • Use spring loaded nozzles – Use spring loaded (positive shut off valves) on all hoses or faucets.