Of the two main types of commercial carwashes, conveyor or in-bay, the conveyor system uses less water. Conveyor systems (where the car moves through a series of cleaning operations) use approximately 44 gallons of water per vehicle and lose 17% of that to evaporation and carryout. In-bay systems (where washing equipment is rotated around a stationary vehicle) use approximately 72.5 gallons per vehicle and lose 33% of the water to evaporation and carryout. Regardless of the type of car wash, recirculating (recycling) systems are an important part of any water-wise car wash. These systems take soapy run-off water, clean it, and send it back for use on another vehicle. See: Water Saving Technologies for Commercial Car Washes (100 KB)

Self-serve vehicle washes use less water than commercial car washes or washing vehicles at home. Typically, self-serve vehicle car washes have an equipment room where water is mixed with cleaning agents which then come out of a wand or brush. Because customers are unsupervised, they often discard oil and debris in the wash troughs making water recycling difficult. Self serve car washes can save water by using pressure nozzles with flow-rates less than 3 gpm, deionization equipment rather than water-softening or reverse osmosis systems for "spot-free" rinse options, and reuse of expelled water if reverse osmosis systems are in place. The expelled water could be used for the wash cycles or to irrigate landscapes.  See: Water Saving Technologies for Commercial Car Washes (100 KB)

Washing a vehicle at home can use 80-140 gallons of water, which is more than the amount used at a commercial car wash! If this option is chosen, using an automatic shutoff nozzle will greatly reduce water waste. Also, washing vehicles on grass or gravel prevents water from running down the street (where much of it evaporates and the rest picks up contaminants) and into storm drains (where it delivers the contaminants). 

See: Water Saving Tips for Washing Your Vehicles (555 KB)