Compare lower and higher observed water use
Illustrative inputs, not verified product specifications or care recommendations.The household question
The same measured count supports two usage assumptions.
Measurements and assumptions
Record A
| Rated capacity (litres) | 600 |
|---|---|
| Litres already used | 500 |
| Litres used per day | 2 |
| Installation date | 2026-01-01 |
| Date of current usage count | 2026-02-01 |
| Manufacturer maximum calendar life (days) | 180 |
| Item name | Compare lower and higher observed water use |
| Storage location | Household supply shelf |
| Minimum stock | 0 |
Record B
| Rated capacity (litres) | 600 |
|---|---|
| Litres already used | 500 |
| Litres used per day | 10 |
| Installation date | 2026-01-01 |
| Date of current usage count | 2026-02-01 |
| Manufacturer maximum calendar life (days) | 180 |
| Item name | Compare lower and higher observed water use |
| Storage location | Household supply shelf |
| Minimum stock | 0 |
Calculation and observed tool result
Record A
Capacity remaining = max(0, 600 − 500) = 100 litres; 100 ÷ 2 = 50 days. Calendar limit 2026-06-30; earlier estimated review 2026-03-23 (50 days from count date).Recorded quantity: 100 litres.
Record B
Capacity remaining = max(0, 600 − 500) = 100 litres; 100 ÷ 10 = 10 days. Calendar limit 2026-06-30; earlier estimated review 2026-02-11 (10 days from count date).Recorded quantity: 100 litres.
Carry out this task
- Open the linked tool for Record A.
- Treat the two rates as alternatives rather than separate cartridges.
- Check each result separately; follow the interpretation before retaining both records as physical stock.
What the result means
The capacity estimates are fifty and ten days respectively.
A mistake to avoid
Changing the used-volume count would alter the wrong assumption.
Limits of this example
Daily use must come from observation rather than this calculator.
Open Water Filter Cartridge Life Calculator · How to Estimate Household Refill Dates