Water Recycling Efficiency Calculator

This calculator models the water economics of a crewed space mission, contrasting what it would cost to bring every drop of water needed versus recycling it in flight. It starts from a NASA-standard daily water requirement of 2.72 kg per person, covering drinking, food rehydration, and hygiene — matching the 2.7 kg/CM-d nominal crew water allocation that NASA lists for short-duration missions in its Life Support Baseline Values and Assumptions Document, based on Orion — and scales that by crew size and mission duration to get the total water that would need to be launched with zero recycling. With a recycling system in place, only the fraction lost to inefficiency (100% minus the system's recovery efficiency) needs replacing each day — the ISS's water recovery system achieves around 93% recovery, which is why that's the default.

The difference between the two totals is the water mass saved by recycling, which the calculator then nets against an estimated system mass (a rough 500 kg base plus 50 kg per crew member, standing in for the hardware needed to run distillation and filtration) to report the actual net launch-mass savings — recycling only pays off once the water saved exceeds what the recycling hardware itself weighs. It also reports how many days an initial water supply would cover the daily makeup water still needed if resupply stopped but the recycling system kept running at its normal efficiency — a basic autonomy/contingency figure for a cutoff in resupply, not a recycling-system failure. The system mass and per-person consumption figures are broad estimates standing in for a real engineering study — actual water recovery systems vary significantly in mass and efficiency depending on the specific technology (distillation, filtration, electrolysis) used.