Seawater

Seawater is a raw input product used by several water-processing buildings, most importantly the Basic Distiller, Thermal Desalinator, and Evaporation Pond. It is handled as a fixed-quantity resource in production comparisons, with 60 Seawater used as the common basis for evaluating recipes and fuel costs.

In the early game, the Basic Distiller is the only available way to process Seawater. Later, the Thermal Desalinator becomes available and is more efficient overall when total setup cost is considered, even after including the Boiler (Coal) required to run it. For the simplest comparison recipe, the Basic Distiller uses 6 coal per 60 Seawater, while the Thermal Desalinator uses 4.5 coal per 60 Seawater. Both buildings have the same net gain of 36 and also produce the same amount in terms of output efficiency, but the Thermal Desalinator wins because it needs less coal.

When Brine is the desired output, the Evaporation Pond is the best choice, as it produces 32 Brine per 60 Seawater. If Salt is the goal, the exact recipe choice does not significantly affect the Seawater cost; the deciding factor is the overall building layout and production setup rather than the water-processing recipe itself.