The Air-to-Water Home Guide

Daily Condensate Yield Calculator

The daily condensate yield calculator answers whether a DIY atmospheric water project can replace enough bottled water to justify hardware. Enter local humidity, operating hours, and collector area; compare the result to household drinking demand before opening the parts list.

Relative humidity (%)Air temperature (°F)Collector area (sq ft)Run hours per daySystem efficiency (0.3–0.9)

Estimated yield: 0.0 L/day (0.00 gal)

Model uses absolute humidity at dry-bulb temperature; real coils add defrost and fan losses. Validate with a graduated collection test over 24 h.

Formula and assumptions

Absolute humidity (g/m³) is approximated from dry-bulb temperature and relative humidity using a polynomial fit to saturation vapor density. Multiplying by collector area, run hours, and a dimensionless efficiency factor yields a mass estimate converted to liters. The model ignores condensate hold-up on fins, intermittent defrost, and parasitic fan heat.

Worked example

At 55% RH, 78°F, 12 sq ft of coil area, 10 h runtime, and 0.65 efficiency, a Gulf Coast garage dehumidifier often lands near 2–4 L/day in field tests—use the calculator, then confirm with a graduated cylinder.

When yield is too low

If modeled output stays under one liter per day, prioritize sanitation articles and consider supplemental municipal filtration instead of expanding coil area.

FAQ

It approximates absolute humidity at dry-bulb temperature. Measured yield should be validated with a 24-hour collection test; coil geometry and fan CFM dominate error.

Packaged dehumidifiers with clean coils often land near 0.55–0.70. Custom cold surfaces without forced airflow may fall below 0.4.

Use the hours when the harvest device actually runs. Nighttime RH spikes help only if the compressor or fan operates during those hours.