Distilled water remains a preparedness staple
Households turn to distilled water for CPAP humidifiers, infant formula, neti pots, battery maintenance, and emergency preparedness. Yet the choice between buying jugs from a delivery service and running a countertop distiller can be confusing. Electric distillers convert tap water into high-purity vapor, condense it, and collect it in a stainless or glass jug. The process removes minerals, organic compounds, and many pathogens, but it consumes energy and requires regular cleaning to prevent scale buildup. Delivered water shifts the burden to a bottling plant and delivery truck but introduces recurring fees, bottle storage, and scheduling. The Home Water Distiller vs Delivery Cost Calculator synthesizes those trade-offs by pairing your daily usage with capital cost, energy demand, maintenance, and carbon footprint metrics.
The calculator supports both countertop and whole-house distillers. Countertop units typically produce 1 gallon every four to six hours and draw 3 to 4 kWh per batch. Whole-house systems integrate with storage tanks, automatic flush valves, and UV post-treatment to serve appliances throughout the home. Regardless of scale, distilled water is energy intensive. The latent heat of vaporization of water is approximately 970 BTU per pound, meaning it takes about 0.3 kWh to evaporate a single liter under ideal conditions. In reality, countertop distillers use roughly 1 kWh per liter due to heat losses and fan motors. By allowing you to input your actual energy usage, the calculator produces a realistic cost per gallon for your setup.
Delivered water pricing varies widely by region. Some services charge $7 to $12 per five-gallon bottle plus a delivery fee, while others bundle unlimited exchanges for a flat rate. The calculator breaks this into a per-gallon cost plus monthly fees, along with a bottle deposit or rental. You can input promotional rates, long-term subscription discounts, or the cost of hauling jugs from wholesale clubs to build an apples-to-apples comparison.
Carbon intensity matters too. Electricity grids emit varying amounts of CO₂ per kilowatt-hour. Truck delivery adds tailpipe emissions and plastic bottle recycling impacts. By entering your regional grid intensity (available from EPA eGRID or local utilities) and a delivery carbon factor, the calculator quantifies which option has a smaller carbon footprint per gallon. Preparedness-minded households often value both resilience and sustainability, so the carbon column makes a compelling case for investing in efficient distillation or coordinating deliveries with neighbors.
From energy to dollars: key formulas
The calculator multiplies daily use by 365 to establish annual demand, then scales by the analysis horizon. Distiller energy cost equals energy per gallon multiplied by daily usage, days per year, and electricity rate. Maintenance includes monthly cleaning supplies plus periodic carbon filters. The capital cost is amortized across the distiller’s lifespan, and if the analysis horizon extends beyond the lifespan, the calculator includes replacement units.
The MathML expression below summarizes the levelized cost of distilled water:
Where LCO is the levelized cost per gallon, C is the sum of capital, energy, maintenance, and filter costs over the horizon, and V is the total volume of distilled water produced. The calculator applies this formula to both the distiller and delivery options so you can compare per-gallon pricing alongside total cash outlay.
Carbon footprint is computed similarly: multiply energy use by grid carbon intensity to get distiller emissions, and multiply delivered gallons by the delivery carbon factor to capture transportation and packaging impacts. Some users add a credit for repurposing waste heat from the distiller (for example, using it to preheat dishwater). If you have a use for the waste heat, subtract that value from the energy cost before entering it in the calculator.
Worked example: CPAP and emergency storage
Imagine a household needing 1.5 gallons of distilled water per day for CPAP humidifiers, countertop appliances, and a small emergency reserve. They consider a $420 countertop distiller rated for 1 kWh per gallon, with a lifespan of six years. Electricity costs $0.17 per kWh. Monthly cleaning supplies (citric acid and brushes) run $7, while carbon post-filters cost $12 every two months. Storage capacity is 3 gallons, enough for daily use plus a small buffer. Delivered water in the area costs $1.35 per gallon, plus a $12 monthly delivery fee and $6 in bottle rental. Delivery trucks emit 0.18 kg of CO₂ per gallon, while the regional grid emits 0.42 kg per kWh.
The distiller consumes 1.5 gallons × 1 kWh × 365 ≈ 548 kWh per year, costing about $93 annually. Maintenance supplies add $84 per year, and carbon filters (6 replacements × $12) add $72, for a total of $249 per year before capital recovery. Amortizing the $420 distiller over six years yields $70 per year. Over a seven-year horizon, the calculator includes one replacement distiller in year seven, bringing the total capital to $840. The levelized cost becomes (energy $651 + maintenance $588 + filters $504 + capital $840) / (1.5 × 365 × 7 ≈ 3,833 gallons) ≈ $0.70 per gallon.
Delivered water costs $1.35 × 1.5 × 365 ≈ $739 per year, plus $12 × 12 = $144 in delivery fees and $6 × 12 = $72 in bottle rental, totaling $955 per year. Over seven years, that’s $6,685 for 3,833 gallons, or $1.74 per gallon. Carbon emissions total 3,833 gallons × 0.18 ≈ 690 kg CO₂ for delivery versus 548 kWh × 0.42 ≈ 230 kg CO₂ for the distiller. The calculator reports that owning the distiller saves about $4,400 over seven years and reduces carbon emissions by roughly 460 kg CO₂ compared to deliveries.
Comparison table insights
The results table presents per-gallon cost, total cost, carbon emissions, and number of replacements required for each option. It also highlights how many days of storage your tank supports given daily usage. If your storage capacity covers fewer than two days, the calculator suggests increasing tank size or scheduling more frequent distillation cycles to avoid running out during power outages.
| Strategy | Energy per gallon (kWh) | Per-gallon cost (USD) | Carbon per gallon (kg CO₂) |
|---|---|---|---|
| Countertop distiller | 1.0 | 0.70 | 0.42 |
| Delivery service | — | 1.74 | 0.18 |
Limitations and assumptions
The calculator focuses on direct financial and carbon costs. It does not account for labor (time spent cleaning the distiller or exchanging bottles), water pre-treatment needs, or the value of independence during boil-water advisories. Some users may need redundancy, such as storing extra filters or adding a backup generator to power the distiller during outages. If you live in an area with high mineral content, scale may accumulate faster than the maintenance schedule assumes; adjust the maintenance cost field to reflect more frequent cleaning.
Ultimately, distilled water decisions balance convenience, safety, and resilience. By quantifying your own usage and utility rates, the calculator equips you to make the choice that fits your household—whether that means committing to regular cleaning of a distiller or negotiating bulk delivery pricing with neighbors.