Verify the inputs
Measure or document each input. If a value is only an estimate, record its source and test a conservative alternative.
Independent energy/ CALCULATOR
Shower water, energy and running cost
Estimate water use, water-heating energy and combined operating cost for a household shower pattern.
FROM ESTIMATE TO ACTION
Use the result, not just the number.
Keep the calculation traceable
Save the input link or copied result together with the date, units and assumptions. A number without its inputs cannot be checked later.
Confirm the decision
Compare the estimate with the related guide, current product data and requirements that apply at your location before buying or building.
Inputs to verify
- Shower flow rate (L/min)
- Measure with a container and timer, or use a verified fixture flow rate.
- Minutes per shower (min)
- Use an observed average rather than the longest occasional shower.
- Showers per day (showers/day)
- Enter the household total averaged over the chosen period.
- Water temperature rise (°C)
- Mixed shower temperature minus incoming cold-water temperature.
- Water-heating efficiency (%)
- Heat delivered to the water divided by purchased energy.
- Calculation period (days)
- Use a billing month, season or year.
- Energy price (currency units/kWh)
- Use the relevant electricity or delivered-fuel energy price.
- Combined water and wastewater price (currency/m³)
- Include wastewater charges when they follow metered water use.