Wells & water/ CALCULATOR
Rainwater storage balance for a dry period
Compare usable tank water with expected demand and dependable inflow over a chosen period.
Use the measured or estimated volume at the start of the scenario.
Volume kept unavailable for uncertainty, sediment clearance or emergency use.
Include only uses supplied from this tank during the scenario.
Use zero for a completely dry scenario; avoid optimistic rainfall assumptions.
Choose a consecutive period relevant to local dry spells or supply interruptions.
Usable starting water
2,550 L
Net daily draw from storage
160 L/day
Storage required for period
2,240 L
Water remaining after period
310 L
Interpretation:The scenario leaves 310 L above the protected reserve.
A simple volume balance with constant demand and dependable inflow. First-flush diversion, leakage, evaporation, water quality, pump limits and changing rainfall are excluded. A negative remaining volume means the scenario needs more storage, less demand or another supply.