Mill Water Balance against a Specific-Consumption Benchmark

The formula

This is the expression the tool evaluates. Every term is named underneath, with the unit it must be supplied in.

How the result is derived

Step by step, from the values you type to the figure on screen.

1. The 9 inputs are read from the form on every keystroke: Daily Production, Specific Water Use, Recycle Rate, Evaporation Loss, Domestic & Non-Process Use, Benchmark Specific Use, Water Cost, Effluent Treatment Cost and Operating Days.
2. Each value is checked against the accepted range in the input table below. A value outside its range stops the calculation rather than producing a misleading figure — the results blank out and a message appears.
3. The validated values are substituted into the expression above, which resolves Specific Fresh Intake together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Process Water Demand, Recycled Volume, Fresh Process Water, Total Intake, Evaporation, Effluent Generated, Discharged to Drain, Gap to Benchmark, Demand Saving Available, Annual Value of that Saving and Recycle Rate that Matches the Benchmark — come from the same pass, so they always describe the same case as the headline figure.
5. Results are rounded for display only. The full-precision value is used throughout the chain, so reading a rounded intermediate figure back into the tool by hand can shift the last digit.

What each input means

Where to read each value on the floor, the unit it must be in, and the range the tool accepts.

What the tool returns

The headline figure and every supporting value it is built from.

Worked example

The tool loads with this case already solved — the Specific Fresh Intake shown above is its answer. Change one value and the difference from this baseline is the sensitivity of the result to that variable.

How to use it

1. Work through the input groups in order — Mill and Benchmark & Cost. The defaults are a realistic case, so you can change one value at a time and watch what moves.
2. There is no calculate button. Every figure recalculates as you type or drag, which is what makes this usable for a what-if sweep rather than a single answer.
3. Read Specific Fresh Intake in the dark results panel — that is the headline figure, expressed in L/kg.
4. Check the supporting rows underneath (Process Water Demand, Recycled Volume, Fresh Process Water, Total Intake, Evaporation, Effluent Generated, Discharged to Drain, Gap to Benchmark, Demand Saving Available, Annual Value of that Saving and Recycle Rate that Matches the Benchmark) before acting on the headline — they are where an implausible input usually shows itself first.
5. Reset to defaults returns every field to the reference case, which is the quickest way to check whether a surprising result came from the tool or from an input you had changed earlier.

Where this is used

• Process planning — establishing Specific Fresh Intake before a trial is booked, so machine time and material in Quality Systems, Traceability, Utilities & Factory Decisions are committed against a calculated figure rather than an estimate.
• Costing and quotation — Specific Fresh Intake is an input to the cost sheet, and quoting from a worked number rather than a remembered one is what keeps a margin intact.
• Troubleshooting — when the floor result drifts from plan, entering the measured values (starting with Daily Production) shows how much of the gap in Specific Fresh Intake each variable explains.
• Teaching and study — the accepted ranges bracket normal Quality Systems, Traceability, Utilities & Factory Decisions practice, so moving one variable at a time shows the shape of the relationship rather than a single answer.

Assumptions and limits

• The balance treats recycled water as fully substitutable for fresh, which it is not: recovered water carries dissolved salts, colour and hardness that accumulate every pass, so most mills can use it in washing, rinsing and cooling and not in dyeing a pale shade or in a boiler. A recycle rate quoted without saying which processes it feeds is not comparable with anything. Evaporation is taken as a share of process demand and covers stenter exhaust, drying cylinders and cooling; it is water that never reaches the drain and therefore never appears in the effluent figure, which is why intake and discharge do not balance and should not be expected to. The last line is deliberately provocative: the recycle rate that would match the benchmark is offered because a mill will often reach for it first, and comparing it with the recycle rate the mill already has usually shows that the benchmark cannot be met by recycling at all - the demand itself has to fall. Specific consumption is also strongly a function of product mix rather than of discipline; a mill dyeing dark reactive shades on cotton cannot reach the figure a polyester disperse house does, and benchmarking across that difference produces a target nobody can hit and everybody stops believing.
• Every input is bounded to the range normal practice occupies (Daily Production 0.1 to 500 t, Specific Water Use 5 to 400 L/kg and Recycle Rate 0 to 90 %, and so on for the rest). Those bounds are guard rails against typing errors, not a claim that the formula fails one unit outside them.
• The calculation is deterministic: the same inputs always give the same result. It carries no allowance for machine condition, operator skill, ambient conditions or lot-to-lot material variation unless an input above explicitly represents one.
• Nothing is sent anywhere. The maths runs in your browser, so the numbers you type never leave the page.

Questions people ask