Count demand rather than bathrooms alone
Describe occupants, simultaneous showers, laundry, a large tub and any additional buildings. Bathroom count is a starting point, not a measured peak flow. Separate irrigation and other high-volume use from the domestic treatment target.
Ask for two different ratings
Service flow and regeneration or backwash requirements answer different questions. Request usable flow at the agreed treatment target, acceptable pressure loss and the supply needed for maintenance cycles. The available pump or utility line may constrain the proposed design.
Make the scope comparable
A proposal should identify tank and media size, valve, settings and which outlets are served. Compare those details alongside installation and future consumables. More stages are not automatically an improvement; every stage should have a purpose supported by the source and household goal.
House, additional buildings and private-well boundaries
For a Wellington request, identify the supply serving each building before discussing equipment. A household connected to municipal water differs from a house on a private well, and a barn or irrigation line may be a separate scope. List the affected outlets and the demand the proposal is expected to serve. Do not apply a domestic equipment recommendation to animal-care or other specialist uses without the relevant professional guidance. A written line map helps the provider assess the correct project.