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What a water filter really costs

The purchase price is the first payment, not the whole bill. Replacement filters, how much you use, and what's left off the page decide the rest.

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Four things to work out

  1. Which parts fit. Replacement filters are often model-specific, so price the parts for the exact model you're considering.
  2. How often each part must change. Most have a time limit and a gallon limit. The one you reach first decides, so a heavier household can pay more per year for the same system.
  3. How much you'll treat each day. Count drinking and cooking water, and be realistic.
  4. What the headline number leaves out. Tax, shipping, electricity, tap water sent to the drain, and early replacement caused by your water or by the machine's own warnings.

A worked example

This example applies that method to two exact models, using their published filter limits. It isn't a verdict on either model: it shows why the cheaper purchase isn't always the cheaper system.

3-year total, by how much water you use
  • AquaTru Classic
  • AquaTru Carafe
$0$500$1,000$1,500$2,000AquaTru Classic at 0.5 gal/day: $764.60AquaTru Classic at 1 gal/day: $764.60AquaTru Classic at 2 gal/day: $804.55AquaTru Classic at 4 gal/day: $1,144.15AquaTru Carafe at 0.5 gal/day: $664.60AquaTru Carafe at 1 gal/day: $704.55AquaTru Carafe at 2 gal/day: $1,044.15AquaTru Carafe at 4 gal/day: $1,773.25$765$1,144$665$1,7730.5 gal/day1 gal/day2 gal/day4 gal/day

Purchase price plus replacement filters at manufacturer list prices checked on November 2, 2026. The table below has the exact figures and what they leave out.

Filter purchases and cost over 3 years, by daily use

AssumptionAquaTru ClassicAquaTru Carafe
Purchase price$475.00[1]$375.00[2]
Rated filter life, whichever comes firstPre/Carbon: 6 months or 600 gal; VOC Carbon: 12 months or 600 gal; Reverse Osmosis: 24 months or 1,200 gal[3][4][5]Pre/Carbon: 6 months or 300 gal; VOC Carbon: 12 months or 300 gal; Reverse Osmosis: 24 months or 600 gal[6][7]
Replacement filter pricesPre/Carbon: $29.95; VOC Carbon: $39.95; Reverse Osmosis: $59.95[3][4][5]Pre/Carbon: $29.95; VOC Carbon: $39.95; Reverse Osmosis: $59.95[8][9][7]
Using 0.5 gal/day3-year total $764.60Filter spend $289.60: 5 Pre/Carbon, 2 VOC Carbon, 1 Reverse Osmosis3-year total $664.60Filter spend $289.60: 5 Pre/Carbon, 2 VOC Carbon, 1 Reverse Osmosis
Using 1 gal/day3-year total $764.60Filter spend $289.60: 5 Pre/Carbon, 2 VOC Carbon, 1 Reverse Osmosis3-year total $704.55Filter spend $329.55: 5 Pre/Carbon, 3 VOC Carbon, 1 Reverse Osmosis
Using 2 gal/day3-year total $804.55Filter spend $329.55: 5 Pre/Carbon, 3 VOC Carbon, 1 Reverse Osmosis3-year total $1,044.15Filter spend $669.15: 7 Pre/Carbon, 7 VOC Carbon, 3 Reverse Osmosis
Using 4 gal/day3-year total $1,144.15Filter spend $669.15: 7 Pre/Carbon, 7 VOC Carbon, 3 Reverse Osmosis3-year total $1,773.25Filter spend $1,398.25: 14 Pre/Carbon, 14 VOC Carbon, 7 Reverse Osmosis
  • Each filter is replaced at its stated time limit or gallon limit, whichever comes first. The set that ships with the purifier covers the first interval.
  • Excludes sales tax, shipping, electricity, tap water, descaling supplies and any early replacement caused by hard water or poor feed-water quality. Electricity is left out because neither manufacturer page we checked publishes wattage.
  • Manufacturer list prices checked on November 2, 2026. Retail prices change: confirm before you buy.
Sources for this table (9)
  1. AquaTru Classic product page, AquaTru. Accessed November 2, 2026.
  2. AquaTru Carafe product page, AquaTru. Accessed November 2, 2026.
  3. Classic Pre/Carbon Filter, AquaTru. Accessed November 2, 2026.
  4. Classic VOC Carbon Filter, AquaTru. Accessed November 2, 2026.
  5. Classic Reverse Osmosis Filter, AquaTru. Accessed November 2, 2026.
  6. AquaTru Carafe Owner's Manual, AquaTru, version 08.22.R3. Accessed November 2, 2026.
  7. Carafe ONLY Reverse Osmosis Filter, AquaTru. Accessed November 2, 2026.
  8. Carafe ONLY Pre/Carbon Filter, AquaTru. Accessed November 2, 2026.
  9. Carafe ONLY VOC Carbon Filter, AquaTru. Accessed November 2, 2026.

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