Bottled Water Cost Calculator
Yearly tap vs bottled water cost from daily liters and per gallon prices.
What it does
Drinking water spans a 500-fold price gap: pennies a year from the tap against hundreds bottled, for the same daily liters. The gap funds convenience and taste, not hydration.
The tool above takes daily liters with both per gallon prices. It returns yearly tap and bottled totals with the extra and ratio.
The default 6 liters a day costs $1.71 tapped against $833.09 bottled, $831.39 extra at 488x. Retail singles at $2 stretch bottled past $1,157.
Prices follow EPA WaterSense bills with IBWA wholesale data and NIST conversions behind them. All three anchor the $0.00295, $1.44, and 3.785412 figures used here.
How to use
- Enter daily drinking liters.
- Enter tap price per gallon.
- Enter bottled price per gallon.
- Read tap yearly first.
- Read bottled yearly beside it.
- Read the extra and ratio.
Formula
- liters
- Liters drunk daily.
- tap price
- Marginal tap $/gal from the bill.
- bottle price
- Bottled $/gal at your format.
- 3.785412
- Exact liters per US gallon.
The gallon factor is exact NIST (3.785412 L). Gallons round to 2 decimals and money to cents at the end. State daily intake apart from household drinking; retail singles land above the wholesale anchor used here.
Worked example
Example: 6 liters a day
Defaults: 6 liters a day, $0.00295 tap, $1.44 bottled per gallon.
- Daily: 6 liters.
- Yearly: 6 x 365 = 2,190 L.
- Gallons: 2,190 / 3.785412 = 578.5 gal.
- Tap: 578.5 x $0.00295 = $1.71.
- Bottled: 578.5 x $1.44 = $833.09.
- Extra: 833.09 - 1.71 = $831.39 (488x).
- Tool shows $1.71/yr, $833.09/yr, $831.39 extra (488x).
Reference table
| Source | $/gal | Note |
|---|---|---|
| Tap marginal | $0.003 | Uniform bill example |
| Bottled wholesale | $1.44 | 2023 domestic |
| Bottled retail | $1 to $2+ | Singles highest |
| Ratio here | 488x | Format decides |
Limits
- Drinking only; whole-home use differs.
- Bills mix fixed fees outside margin.
- Taste and source vary by system.
- Health claims sit outside price.
Common mistakes
- Pricing singles as jugs.
- Using average bills for marginal gallons.
- Forgetting daily intake vs household.
- Skipping filter middle paths.
- Comparing months to years.
Try it yourself
Quick checks. Answers sit tucked under each question.
2 liters a day, $0.003 tap, $2 bottled?
192.9 gal: $0.58 tap vs $385.69 bottled, $385.11 extra (667x).
Defaults at $2 retail?
578.5 x $2 = $1,157.08 bottled.
Yearly gallons per daily liter?
365 / 3.785412 = 96.4 gal a year from 1 liter a day.
Questions
What does tap water cost?
About $0.003 per gallon marginal (3 cents per 10 gallons) on uniform bills. Fixed fees sit outside.
What does bottled water cost?
About $1.44 wholesale per gallon; retail single serves run $1 to $2 plus per gallon.
How is the yearly total built?
Yearly gallons = daily liters x 365 / 3.785412, then times each price.
Does bottle format matter?
Yes. Bulk jugs near wholesale while single serves cost far more per gallon.
Why is tap even cheaper at margin?
Tap bills mix fixed plus volume charges, so extra gallons cost less than the average bill suggests.
Are filters a middle path?
No. Filter pitchers and fridge filters split the difference for taste without bottle prices.