Home Water Distiller vs Bottled Water Lifetime Cost Calculator

Table of contents

• How to use
• Common mistakes
• Definitions
• Methodology
• Limitations & assumptions
• Sources

Bottled water price per gallon: The package price divided by the total gallons in that package. It lets cases, jugs, and refills be compared on the same basis.

kWh per gallon: Kilowatt-hours of electricity used to make one gallon. This is energy use, not the machine's watt rating.

Electricity rate: The energy charge in dollars per kWh. The default is a US residential planning estimate; replace it with your own rate when possible. [1]

Break-even month: The first whole month when the accumulated bottled-water cost is at least the accumulated distiller cost.

Replacement distillers needed: Machines purchased after the first distiller because the comparison period lasts longer than one machine's expected life.

Fluid ounce: A US liquid-volume unit. This calculator uses 128 US fluid ounces per US gallon. [2]

Mistake: Entering the full case volume in Bottle or jug size and also entering the bottle count in Containers in one package.
Fix: Enter the size of one bottle or jug, then enter the number of identical containers in the package.

Mistake: Choosing gallons for Bottle or jug size unit when the label says fluid ounces.
Fix: Match the unit printed on the container. The calculator converts 128 fluid ounces to one US gallon.

Mistake: Using the full monthly electric bill as Electricity rate.
Fix: Enter the energy charge in $ per kWh from the bill or rate plan, not the total bill with fixed fees and taxes.

Mistake: Entering watts as Electricity used per gallon.
Fix: This field needs kWh per gallon. Use a manual value or divide measured cycle kWh by gallons made in that cycle.

Mistake: Treating a negative Distiller savings over the comparison period as an error.
Fix: A negative amount is valid. It means bottled water costs less by that amount over the selected years.

Mistake: Leaving out recurring charges from a delivery invoice.
Fix: Put water charges in Bottled water package price, then add recurring service charges in Bottled water delivery fee and Bottle rental or deposit cost when they apply.

• The calculation is a planning estimate, not a store quote or utility bill forecast.
• Weekly use is annualized with 52 weeks per year. Actual use can vary by season, guests, appliances, or changes in household size.
• Bottled-water spending is treated as proportional to gallons. It does not round purchases up to whole cases, jugs, coupons, sales tax, or changing store prices.
• The distiller cost includes the entered equipment, replacements, electricity, annual filters, and annual cleaning. It excludes repairs unless you include them in a yearly cost.
• Existing fixed electric-account charges are excluded because they normally do not change when a distiller is used. Only the entered electricity energy rate is applied.
• A replacement is charged only after a machine's full entered service life is used. No replacement is charged exactly at the end of the comparison period.
• Use the comparison only for water products that meet your intended purpose. Cost alone does not determine water quality, suitability, storage needs, or safety.

Cost calculation

The calculator first converts the entered package into gallons. A gallon selection uses the entered size directly; a fluid-ounce selection is divided by 128. It then applies the same estimated water use to both paths.

package gallons = container size x containers in one package x unit-to-gallons factor

bottled water price per gallon = bottled water package price / package gallons

lifetime gallons = water used each week x 52 x compare costs over

The distiller path includes the first machine, any needed later machines, electricity, filter cost, and cleaning cost. A blank replacement price uses the original distiller purchase price.

replacement distillers needed = ceil((compare costs over x 12) / (expected distiller life x 12)) - 1

distiller cost over the comparison period = equipment cost + lifetime gallons x electricity used per gallon x electricity rate + compare costs over x (distiller filter cost + distiller cleaning cost)

The bottled path includes water purchases plus any monthly delivery and rental charges.

bottled water cost over the comparison period = lifetime gallons x bottled water price per gallon + (compare costs over x 12) x (bottled water delivery fee + bottle rental or deposit cost)

distiller savings over the comparison period = bottled water cost over the comparison period - distiller cost over the comparison period

Break-even and example

The calculator checks each whole month in order and reports the first month when accumulated bottled-water cost is at least accumulated distiller cost. Replacement purchases are included in the month after a machine has completed its entered life.

break-even month = first month where bottled cost through month >= distiller cost through month

For example, a $6 package containing six 1-gallon jugs costs $1 per gallon. At 5 gallons per week for 10 years, planned use is 2,600 gallons. With a $150 distiller, a 5-year life, 3 kWh per gallon, and $0.173 per kWh, equipment costs $300 because one replacement is needed and electricity costs $1,349.40. Before optional yearly or monthly costs, the distiller path costs $1,649.40 versus $2,600 for bottled water, for savings of $950.60.

Assumptions and limits

Calculations use 52 weeks and 12 months per planning year. Money is rounded only for display. The default electricity rate is a planning estimate, so a utility bill's energy charge can produce a more personal result. [1]