Bottled vs Filter Cost Calculator

Bottled water: Annual cost = (people × oz/day × 365) ÷ 128 oz/gallon × your bottled price per gallon × your bottled %.

Default scenario: a family of 4 drinking 64oz each per day = 73 gallons per person per year, 292 gallons total. At $5.99/24-pack (about $0.50/gallon for case bottles), that's $146/year. At Dasani prices ($12/gallon), the same household spends $3,500+ per year.

Filtered water: Annual cost = system price (amortized) + replacement cartridges. Most under-sink systems are $150–300 with $60–100/year in cartridges, working out to $0.05–0.15 per gallon. Whole-house and RO are higher upfront but lower per-gallon long-term.

The difference is your annual savings. Most households save more than the system costs in the first year alone.

The "bottles eliminated" number assumes you're currently using 16.9 oz disposable bottles (the most common size). Each gallon = 7.57 bottles. Multiply your annual gallons × 7.57 to see your bottle count.

The CO₂ figure uses ~82.8g (0.18 lb) of CO₂ emitted per single-use plastic water bottle, which accounts for production, packaging, transport, and end-of-life. This is from Pacific Institute and EWG-cited industry data — bottled water is one of the most carbon-intensive drinks per ounce because it's heavy, ships long distances, and has high packaging-to-product ratios.

Filtration generates a small amount of waste (replacement cartridges, RO wastewater) but the comparison is dramatic — a single under-sink filter cartridge replaces approximately 300 plastic bottles before needing replacement.

Pitcher filter ($25–80): Cheapest entry point. Carbon block reduces chlorine, taste, and some metals. Good for renters, dorms, or testing the waters before a bigger investment. Filter every 1–2 months. Cost per gallon: 15–25¢.

Faucet-mount ($30–100): Screws onto your faucet. Better flow than pitchers, similar filtration quality. Best for kitchens where you want filtered water on demand without a big install. Cost per gallon: 10–15¢.

Under-sink standard ($150–300): Permanent install, dedicated faucet or splits to existing tap. Multi-stage carbon filtration handles more contaminants. Cost per gallon: 5–10¢. The sweet spot for most households.

Under-sink RO ($250–600): Adds reverse osmosis membrane that strips dissolved solids (TDS) — essential if you have very hard water, well water with high mineral content, or just want truly bottled-water-clean taste. Cost per gallon: 8–15¢ (factoring 2:1 wastewater ratio).

Whole-house ($500–2000): Treats every faucet, shower, and appliance in your home. Best for well water, hard water (scale on appliances), or high-chlorine municipal water. Cost per gallon spread across all home water use is the lowest of any option.

If you're not sure which contaminants you should be targeting, run a home water test ($25–40) or check your municipal water report — the EPA requires utilities to publish a Consumer Confidence Report annually.

Cooking and ice: If you cook with filtered water and freeze ice from it, your real total filtered water usage is much higher than just drinking — but this calc focuses on drinking water specifically because that's what bottled water replaces.

Travel and on-the-go: A reusable insulated bottle (Yeti, Hydro Flask, Stanley) that you fill at home before leaving largely solves the "bottled water for convenience" use case. The calculator assumes 100% of drinking is at home; subtract for genuinely-on-the-go situations.

Filter maintenance time: Pitcher filters need monthly attention. Under-sink and whole-house need cartridge changes 1–2 times per year. Not factored in monetarily, but real if you forget — performance drops dramatically when filters are overdue.

Water quality reality: This calc focuses on cost, not safety. If your tap water has lead, PFAS, nitrates, or other serious contaminants, you need filtration regardless of cost — and you should specifically choose a system certified to remove those contaminants (look for NSF/ANSI 53 or 58 certifications).