Evidence for repair
A defined leak, damaged head or failed controller may be addressable without rebuilding the system. Request the diagnosis and identify which existing components would remain. A history of repeated work in the same location deserves particular attention.
Evidence for broader changes
Landscape redesign, poorly matched zones or widespread deterioration can justify a larger proposal. Ask the installer to distinguish necessary replacements from optional upgrades and explain how the new design resolves the documented issues.
Compare like-for-like scopes
Include excavation, controls, backflow arrangements, restoration, commissioning and documentation where applicable. A repair quote and a replacement quote may exclude different items, making headline totals misleading.
Useful question
If I choose the smaller repair now, what limitations will remain and what evidence would justify revisiting replacement later?