A wash line raises two different questions: what does it cost to make one container clean and ready for use, and can the line meet demand on a busy day? The total on a bill alone answers neither.
Cost per released container
Period cost = water + water-heating and other energy + detergent/disinfectant + direct labour + maintenance + wastewater cost. Cost per ready container = that total / containers cleaned, dried, inspected and released in the same period. Track rewashed, damaged or held containers separately; do not count them as released.
For a trial period, match meter readings and invoices to shifts. Record container count, programme, wash duration, drying and inspection time. For capacity, track completed containers from dirty receipt to clean stock and queue time, not just the washer's hourly cycle count.
When comparing an in-house line with an outside service, use the same hygiene acceptance criteria, volume, transport distance and drying responsibility. Show space, shift or transport costs separately if they are excluded from the quote. ISO 18616-1 defines container types and dimensions; it does not by itself validate a particular line's hygiene result or wash time.
