Compare cost and CO₂e of the same volume as bottled water versus tap water.
| Bottle cost | – |
| Tap cost | – |
| Bottle kg CO₂e | – |
| Tap kg CO₂e | – |
Use this calculator when you are deciding whether to keep buying bottled water or switch to the tap for a known daily volume.
Cost is volume × the price you type for each option. Carbon is volume × 0.2 kg CO₂e per litre (bottled PET ballpark) or × 0.0003 kg CO₂e per litre (municipal tap ballpark). Volume can be entered in litres (L) or gallons (gal); it is converted to litres before the formula.
Prices are in your currency per litre-equivalent. The carbon factors ignore cold-chain and glass; edit nothing here except volume and prices.
Volume: How much water you want to compare, in L or gal. 2 L is a common daily figure.
Bottle price / L: What you pay per litre of bottled water, e.g. 0.50.
Tap price / L: What you pay per litre from the tap, often a fraction of a cent, e.g. 0.002.
Bottle / tap cost: Spend for that volume.
Bottle / tap kg CO₂e: Carbon of that volume on each path.
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