Shower Water and Energy Cost Calculator
Enter your shower time and flow rate to see how much water and energy your showers use.
Your numbers
Hot shower about 40 °C minus cold water temperature
%
Use about 300% for a heat pump water heater
$
$
Your results
Yearly cost (energy + water)
Yearly cost (energy + water)
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Water per year (litres)
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Heating energy per year (kWh)
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Cost per shower
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Yearly saving at the new flow rate
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Shower Water and Energy Cost Calculator by TheCalcTools
How the Shower Water and Energy Cost Calculator works
Water used = flow rate × minutes × showers. Heating it takes 4.186 kJ per litre per °C (the specific heat of water), divided by your water heater’s efficiency.
Low-flow shower heads cut both water and heating energy in proportion to the flow rate.
The formula
kWh = litres × 4.186 × ΔT ÷ 3,600 ÷ efficiency
Worked example
Using the default values shown in the calculator:
| Shower flow rate (L per minute) | 9 |
|---|---|
| Shower length (minutes) | 8 |
| Showers per week (household) | 14 |
| Temperature rise (°C) | 28 |
| Water heater efficiency | 90 % |
| Energy price per kWh | $0.25 |
| Water and sewer price per 1,000 L | $3 |
| New flow rate for comparison (L/min) | 6 |
- 9 L/min × 8 min × 14 a week × 52 = 52,416 L a year.
- Heating it takes 1,896 kWh; total cost $631 a year.
Result:
| Yearly cost (energy + water) | $631 |
|---|---|
| Water per year (litres) | 52,416 |
| Heating energy per year (kWh) | 1,896 |
| Cost per shower | $0.87 |
| Yearly saving at the new flow rate | $210 |
Frequently asked questions
How do I measure my shower's flow rate?
Time how long it takes to fill a 1-litre jug or bucket: 1 litre in 6 seconds is 10 L/min.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.