Choose service flow above realistic household peak demand, then verify the well pump can supply the manufacturer’s backwash rate without collapsing pressure. Do not size from bathroom count alone.
Service flow protects household pressure
A filter undersized for peak use can cause pressure complaints when multiple fixtures run. Continuous service flow is the most useful comparison number for normal operation.
Backwash flow protects the filter media
Air-injection and other regenerating media systems need adequate backwash velocity to lift and clean the bed. Insufficient flow can shorten media performance even when household faucets seem fine.
SpringWell example
Current SpringWell documentation lists WS1 at 12 GPM service and 5 GPM backwash, while larger WS4 documentation lists a higher backwash requirement.
Measure pump output, not only pressure-switch settings
A 40/60 pressure switch does not prove the well can deliver the needed GPM. Pump curve, well yield, pressure tank and plumbing restrictions all matter.