1. Establish the baseline
Use matching meter and vehicle intervals. Record fresh water per vehicle, daily throughput, cleaning demand and operating variation.
2. Draw the stream map
Identify which arches or functions require fresh, spot-free or reclaimed water. Show carryout, evaporation, RO reject, backwash, sludge and sewer paths separately.
3. Verify reclaim eligibility
Confirm with the equipment supplier and applicable authority which wash steps can accept reclaimed water and what pretreatment, separation and monitoring are required.
4. Build the quantity balance
Use measured gross applied water and entered collection/recovery performance. Cap reclaim by the process volume actually eligible to receive it.
5. Test the peak window
Model the busiest realistic throughput, starting tank level, return delay, working tank volume and reserve. A daily average cannot prove peak continuity.
6. Plan spot-free production
Use measured RO permeate production at actual feed conditions, not nameplate output alone. Compare daily and peak demand, storage and reject routing.
7. Check economics
Apply current water and sewer tariff rules, added power, consumables, maintenance and installed cost. Test lower throughput and lower recovery cases.
8. Commission and monitor
Repeat per-vehicle water use and stream measurements after commissioning. Track tank levels, product quality, odor, solids, alarms, filter service and abnormal discharge.
9. Stop at the safety boundary
Quantity tools do not select treatment or approve discharge. Use qualified environmental, electrical, plumbing, equipment and workplace review for the actual site.
Worked example
A 120 vehicle/day site reduces fresh use from 180 to 72 L/vehicle. At 300 operating days, the fresh-water reduction is 3,888 m³/year; the final decision still depends on verified sewer savings, operating cost, peak tank behavior and acceptable reclaimed-water quality.
Sources
- U.S. EPA WaterSense at Work — Vehicle Washes
- U.S. Department of Energy — Vehicle Wash Water-Use Estimating Methods
- International Carwash Association — Water Use, Evaporation and Carryout
- U.S. Department of Energy — Handbook of Water Use and Conservation