Where exterior cleaning water actually goes
Exterior cleaning is not one line item. It is usually three or four different jobs with very different water behaviour, and each of them has to be looked at separately.
- Daily wipe-down of the enclosure panels, chip-conveyor covers and control-cabinet fronts. This is bucket-and-rag work, so water use is low per event but easy to repeat many times per shift.
- Removing cutting-fluid film and coolant mist residue that has crept across the sheet-metal bodywork and the paintwork around the doors.
- Hose or pressure-wash washing of the machine base, the floor surround and the walkways, which is normally the largest water consumer in the group.
- Periodic deep cleaning before relocation, an overhaul or an audit, which is infrequent but heavy, and distorts a monthly average if it is not tagged separately.
Worth separating as well: coolant management, sump changes and internal wash-down are not exterior cleaning. If those volumes are mixed into the same figure, the exterior number becomes useless for any decision.
Three ways to measure the same job
Most sites try to start with the building water meter. That gives an accurate plant figure and no attribution at all — you know the shop used water, not which machine or which shift used it. The workable route is to measure the cleaning task itself.
The simplest method is a bucket count, or a totalising tap meter clipped onto the wash-down hose reel. Water use in these jobs is roughly a function of run time multiplied by the flow of the device, so counting litres per wash event, plus the number of events, produces a defensible figure without any instrumentation project. Where the site wants a cleaner answer, a small inline turbine meter on the wash-down supply, read at the start and end of the shift, does the same job with less reliance on discipline.
The third route is to record time and device power instead of water directly — relevant when the cleaning device heats or pressurises its own supply, as industrial steam cleaning equipment does. In that case water is carried into the machine in a tank, so the tank refills per shift become the read-out, and the energy figures come from the same run log.
Building a per-machine baseline in two weeks
A baseline does not need software. It needs a sheet with a fixed set of columns, filled in by whoever does the cleaning, for long enough to cover the real cycle rather than one representative week.
| Column | What it captures |
|---|---|
| Machine ID and zone | Which asset and which area of the shop, so totals can be compared like for like |
| Date and shift | Exposes whether night-shift crews clean differently from day crews |
| Job type | Wipe-down, degreasing of fluid film, hose wash, or deep clean |
| Litres used | Bucket count, meter reading or tank refills |
| Run time and labour minutes | Water per hour and water per job, which is what you compare after a change |
| Chemificant, dose and contact time | Reveals whether extra water is being spent compensating for too little dwell time |
| Rinse passes and finish check | Shows how much water is re-work, i.e. cleaning that failed the first time |
Two weeks of this data is usually enough to see the pattern. Read it as litres per machine per event, not as a shop total, and the outliers become obvious: one machine that always needs a second rinse, one crew that leaves the hose running, one zone where the floor wash does double duty as a drain flush.
What skews the numbers
- Frequency that nobody planned. Ad-hoc wipe-downs "while the machine is idle" are the water that never shows up in a plan.
- Rinse count. A surface still tacky with cutting-fluid residue gets rinsed again, and the second pass is charged to nobody.
- The hose running between passes. On an open hose reel this is often the single largest controllable loss in the group.
- Deep-clean events folded into a monthly figure without being labelled.
- Weather and season in shops that wash in bays that drain to the outside, where standing water has to be cleared.
Reading the results against your cleaning method
The point of measuring is to decide what to do next, and the baseline usually points to one of three actions. If rinse passes dominate, the lever is dwell time and temperature on the soil, not a lower-flow nozzle. If floor and base washing dominate, the lever is how the wash bay drains and how often the wash is repeated. If labour hours dominate while water looks modest, the job is being done slowly with low-flow tools and the real cost is people.
For comparison purposes, treat high-temperature steam as a different class of method rather than a lower-flow hose. Dry-steam work on a fixed steam cleaning machine such as the PowerDe HW02 carries its supply in an on-board tank — the detail page lists an 80 L SUS304 tank, a tap-water inlet, dry and wet steam modes and a built-in vacuum function, with the protective functions named on the page rather than counted. Judged on the water ledger, the tank refill per shift becomes the measure, and the same run log gives you the heating and cleaning time. The HW02 page positions the machine for vehicle exterior cleaning at stations and parking areas, interior work and engine-compartment cleaning, so it is the shop-vehicle, fleet and service-bay side of a plant that gets assessed this way, not a claim about machining centres. For machinery-side work, review CNC machine cleaning equipment options with the supplier and confirm suitability for the specific soils in your shop before specifying anything.
Whatever method you then trial, measure it the same way as the baseline and compare litres per machine per event, labour minutes per event and first-pass acceptance. If the trial does not improve at least two of those three, it is not a saving — it is a different cost with a similar total.
FAQ
Is the building water meter enough?
No, unless cleaning is the only thing that draws water. Use the meter as a sanity check on your totals and measure the task directly for anything you intend to act on.
How long should the baseline run?
Long enough to include every shift pattern and at least one deep clean. For most shops two weeks is a practical minimum; longer is better if the schedule is irregular.
Should the figures be kept per machine or per area?
Per machine, with area totals derived from it. Per-area data hides which asset is driving the consumption, and per-machine data can always be rolled up.
Once the baseline exists, the question stops being "how much water do we use?" and becomes a normal purchasing question: which method gives the same finish with fewer litres, fewer labour minutes and fewer re-work passes. Ask a supplier to quote against your measured figures rather than against their datasheet, and the comparison takes care of itself — details are on the PowerDe cleaning equipment pages or through the contact form.
