Fictional worked example

Compare showerheads at the same duration

A resident measures 5 L in 30 seconds before changing a showerhead and 3 L in 30 seconds afterward. Compare the two measured flows for a seven-minute shower.

Open Calculator

Inputs and calculation

10 L/min before replacement
Tool inputValue
CurrencyUSD
Volume or billing unitm³
Activity measurementFlow over time
Flow (L/min)10
Minutes per occurrence7
Occurrences per person per day1
People (1 for shared use)1
Days or equivalent sessions30
Price per billing unit (USD)4

10 L/min × 7 min × 1 × 1 × 30 = 2100 L. Divide by 1,000 for m³ and multiply by 4 for USD 8.40.

Tool result · USD 8.40

6 L/min after replacement
Tool inputValue
CurrencyUSD
Volume or billing unitm³
Activity measurementFlow over time
Flow (L/min)6
Minutes per occurrence7
Occurrences per person per day1
People (1 for shared use)1
Days or equivalent sessions30
Price per billing unit (USD)4

6 L/min × 7 min × 1 × 1 × 30 = 1260 L. Divide by 1,000 for m³ and multiply by 4 for USD 5.04.

Tool result · USD 5.04

Longer shower after replacement
Tool inputValue
CurrencyUSD
Volume or billing unitm³
Activity measurementFlow over time
Flow (L/min)6
Minutes per occurrence10
Occurrences per person per day1
People (1 for shared use)1
Days or equivalent sessions30
Price per billing unit (USD)4

6 L/min × 10 min × 1 × 1 × 30 = 1800 L. Divide by 1,000 for m³ and multiply by 4 for USD 7.20.

Tool result · USD 7.20

What the comparison shows

Equal-duration savings are 840 L. At ten minutes after replacement, only 300 L of that baseline difference remains.

Assumptions and limits

Flow depends on pressure and valve position. A longer shower can offset a lower flow.

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