When to use this calculator
Changing flow rate affects both water use and the energy needed for hot water, though heating energy is not included here.
Explore the water use & conservation calculators for other questions in this topic. For a related calculation, use the Stored Water Supply Days Calculator: Estimate how long usable stored water lasts at a fixed daily withdrawal.
PUTTING IT INTO PRACTICE
Shower Water Saving: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Old flow (L/min) | 12 |
| New flow (L/min) | 8 |
| Minutes per shower | 10 |
| Showers per period (integer) | 30 |
| Result | 1,200 litres |
- Check the input labels and enter the example values above.
- Apply the relationship: Water saved = (old flow − new flow) × minutes × showers.
- The result is 1,200 litres, rounded for display.
How to interpret your result
Assumes shower length stays the same. Negative savings mean increased use.
Use measured flow rates when possible. A rainfall volume estimate is not a storage simulation and can exceed tank capacity. Fixed water charges and sewerage charges may follow separate tariff rules.
Frequently asked questions
Can rain collected exceed tank capacity?
The geometric collection estimate can. Storage, overflow, first-flush diversion and use during rainfall need a separate tank model.
When is the shower water saving calculator useful?
Changing flow rate affects both water use and the energy needed for hot water, though heating energy is not included here.
How do I use the shower water saving calculator?
Enter old flow (l/min), new flow (l/min), minutes per shower, showers per period (integer). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Water saved = (old flow − new flow) × minutes × showers.
What should I check before using the result?
Assumes shower length stays the same. Negative savings mean increased use.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
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