More in Daily Frugality
What this calculator does
Bottled water is convenient but expensive. This calculator compares the yearly cost of cases to a filter and refill cartridges.
The math
Bottled annual = cases per month × cost per case × 12. Filter annual = filter cost + refills × refill cost × 12.
Worked example
Four $4 cases per month costs $192 per year. A $15 filter plus two $0.50 refills per month costs $27 per year.
Why this matters
Small daily habits are the easiest to change and the fastest to compound. This calculator shows the real savings from one swap.
Methodology and transparency
This page publishes the exact formula used to compute the result, so you can verify it in a spreadsheet or check the assumptions against your own situation. The worked example uses the tool default inputs; change any number and the result updates live in your browser. No data is sent or stored.
Common questions
Is tap water safe?
It depends on your location. A filter can address taste and many contaminants.
What about environmental cost?
This calculator only covers money. Bottled water has a much higher environmental cost.