Bottled Water vs Filter Calculator
Compare a bottled-water habit against a home filter — setup, replacement cartridges and all — and see the yearly savings.
How it works
Bottled/year = bottles/day × price × 365 · Cartridges/year = (365 ÷ cartridge days) × cartridge cost · Filter year 1 = upfront + cartridges/year
The honest comparison charges the filter its full setup plus a realistic cartridge-replacement schedule, not just the sticker price of the pitcher. Bottled water looks cheap per unit but its cost is entirely recurring, while a filter front-loads a small fixed cost and then drops to just cartridges. That is why the first-year saving understates the long-run gap — every year after year one drops the upfront cost entirely.
Worked example
Four $1 bottles a day is 4 × 1 × 365 = $1,460 a year. A $35 pitcher plus $8 cartridges every 60 days costs 35 + (365 ÷ 60 × 8) ≈ $35 + $48.67 = $83.67 in year one, so filtering saves about $1,376 the first year and more each year after.
Frequently asked questions
Does this account for taste or water quality?
No — it is a pure cost comparison. If your tap water needs specific treatment, price a filter certified for that contaminant; the running-cost math still applies once you know the cartridge schedule.
Why is the ongoing cost lower than the first year?
Year one includes the one-time setup cost of the filter system. After that you only pay for replacement cartridges, so every subsequent year is cheaper than the first.
What if I use a plumbed-in or fridge filter?
Enter its installed cost as the upfront figure and its cartridge cost and lifespan the same way. More expensive systems simply push the break-even point a little later.
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This calculator is for educational purposes. Double-check important results before acting on them.