Quick take
WS1 is the mainstream choice for 1–4 bathrooms at 12 GPM service. WS4 is the large-home option at 20 GPM service and a 13-inch tank. Choose WS4 only when household demand and well-pump capacity support the larger system.
WS1 specifications
SpringWell currently lists WS1 for 1–4 bathrooms, a 10-inch tank, 12 GPM service flow and 1-inch connections.
WS4 specifications
Current product specifications list WS4 for 4+ bathrooms, a 13-inch tank, 20 GPM service flow and 1-inch connections.
Backwash matters when moving up
The larger media bed needs stronger cleaning flow. Confirm the well pump and plumbing can sustain the model-specific backwash demand before selecting WS4.
Water test still comes first
SpringWell requires or strongly emphasizes current well-water testing because flow sizing does not prove the treatment chemistry is appropriate.