Build a short equipment history
Record model, age if known, recent changes, service dates and the symptom. A salt bridge, control problem and exhausted media are different repair categories. Ask for the diagnosed cause rather than accepting age as the only reason to replace equipment.
Compare complete costs
Have both options describe labor, components, warranty terms, plumbing changes and recurring service. A replacement can make sense when capacity or serviceability no longer fits, but that conclusion should be explicit. A low repair price that excludes a necessary second visit is difficult to compare.
Use an acceptance check
Agree on the result that closes the job: treated hardness, restored flow or an appropriate target-specific check. Keep baseline and startup evidence. Do not assume that replacing one stage also repairs a separate drinking-water system, heater or pump.
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.