Bottled Water Cost Calculator
See what buying bottled water really costs you a year, compared with tap water or a filter jug — plus how many plastic bottles that adds up to and what the saving could be worth if you invested it instead.
Estimate only. This calculator is for general budgeting guidance only, using typical UK average tap water pricing. The invested-instead figures are an illustrative projection at a fixed, editable growth rate — growth is not guaranteed and investments can fall in value as well as rise. Not financial advice.
That's 728 single-use plastic bottles you could avoid.
If you invested that saving instead
Illustrative projection only — growth not guaranteed. Assumes you keep investing the monthly saving at the rate above.
| Years | Contributed | Interest earned | Could be worth |
|---|---|---|---|
| 10 | £8,004 | £2,353 | £10,357 |
| 20 | £16,008 | £11,408 | £27,416 |
| 30 | £24,012 | £31,500 | £55,512 |
Ways to cut the cost (and the plastic)
- Look for free water refill points — most UK train stations, many high-street cafes and the Refill app (refill.org.uk) show where you can top up a reusable bottle for free.
- Keep a reusable bottle at your desk or in your bag — most of the cost of bottled water comes from convenience buys when you're out, not from planned shopping.
- A basic filter jug pays for itself within a couple of months if you're currently buying more than a couple of bottles a week, and tap water in the UK is treated to the same safety standard either way.
- If taste is the main reason you buy bottled water, chilling a jug in the fridge overnight often solves it — cold tap water tastes noticeably better than room temperature.
How the bottled water cost is worked out
This calculator multiplies your bottles per week by the price per bottle and 52 weeks to get your annual bottled water spend, then compares it with two cheaper alternatives: tap water, priced at roughly £0.1p per litre based on typical UK household water and wastewater bills, and a filter jug, priced at the annual cost you enter for the jug and cartridges combined. The saving shown is against whichever of those two is cheaper for you, and the plastic bottle count is simply bottles per week × 52 — a rough guide to how much single-use plastic that habit uses each year.