What happens if my actual household water usage exceeds the calculator’s assumption?

If your real usage consistently runs higher than the calculator's baseline, whether due to household size, lifestyle or garden watering, you may find yourself relying more heavily on tanker top-ups or facing more frequent low-water situations than expected. It is worth erring toward a somewhat larger capacity than the bare calculated minimum, particularly for the sump, since sump capacity is much cheaper to size generously at construction stage than to retrofit later.