Pump-only countertop RO usually has modest electricity use. Hot-water and refrigeration features can dominate energy consumption, so compare appliance features rather than assuming all countertop RO systems cost the same to run.
Pump energy
RO booster pumps operate mainly during purification, so their energy use scales with daily water production.
Heating changes the equation
Instant-hot countertop systems use high power briefly while heating. Total energy depends on dispensing volume and whether the unit maintains stored hot water.
Chilling can add continuous load
Models with refrigerated cold-water tanks may cycle a compressor throughout the day, making them closer to a small appliance than a simple filter.
Compare total ownership cost
For RKIN U1, JIMMY R9 and other feature-rich systems, electricity belongs alongside replacement cartridges and purchase price in a fair comparison.