Tap Water vs Bottled Water Calculator
What bottled water costs against tap — in money, emissions and plastic, over a year.
Tap water costs on the order of 0.
How the tap water vs bottled water calculator works
Tap water costs on the order of 0.002 per litre in most developed countries. Bottled water costs 1 to 3 per litre — a markup of between 500 and 1,500 times.
The emissions gap is similar: about 0.3 g CO₂e per litre from the tap against roughly 250 g for bottled, once production, filling and transport are counted. The filter row shows where a reusable bottle plus a filter lands.
Formula: annual cost = litres × price per litre
Worked examples
| Inputs | Annual saving from tap water | Note |
|---|---|---|
| 2 L a day | 1,458.18 | 1,458 a year saved |
| A family of four | 5,832.7 | four times the saving |
| Cheaper bottled water | 582.18 | still a large gap |
FAQFrequently asked questions
How much more does bottled water cost?
Typically 500 to 1,500 times the price of tap water per litre.
Is bottled water safer?
In countries with treated mains supply, generally no. Tap water is usually tested more frequently and against stricter standards than bottled.
What about the emissions?
Roughly 250 g CO₂e per litre bottled against 0.3 g from the tap — production, filling and transport dominate.
Is a filter worth it?
For taste, often. This page subtracts the filter cost so the comparison stays honest.
What if my tap water is not safe?
Then this comparison does not apply. Where the mains supply is unreliable, bottled or filtered water is a health decision, not a cost one.
Where these figures come from
- UK DESNZ / DEFRA — Greenhouse gas reporting: conversion factors — the flight, fuel and waste emission factors used here
- Scarborough et al. (2014), Climatic Change — Dietary greenhouse gas emissions — the per-diet daily emission figures
- US EPA — Technical Assistance Document for the Reporting of Daily Air Quality (AQI) — the PM2.5 breakpoints the air quality calculator uses
- UK Department for Energy Security and Net Zero — conversion factors — the official UK emission factors
Last checked: September 2026. Factors are taken from published government and peer-reviewed sources, each named on the page with its year.