What this tool does
Show no-refill and partial-refill water balances, then distinguish required usable volume from the tank’s nominal physical volume.
When to use it
Use for preliminary outage, slow-source or scheduled-refill scenarios after demand and source availability have been explicitly estimated.
Inputs and supported units
Each labelled field explains the quantity it expects. Unit-system changes convert existing numeric entries once and keep calculations on a single SI internal basis. Supported shared units include L/min and GPM, metres and feet, kPa and psi, millimetres and inches, kW and hp, and °C and °F as relevant.
Calculation or decision method
How to interpret the result
Read the primary result with the supporting breakdown and warning. A plausible number is not evidence that every input, operating case or design constraint has been included.
Worked example
At 2,000 L/day for 3 days with 5 L/min refill for 4 hours/day, refill contributes 3,600 L. The 2,400 L net plus 20% reserve is 2,880 L usable; at 90% usable fraction, nominal storage is 3,200 L.
Assumptions
Average refill occurs for the entered hours each day, demand is represented by a daily total and the usable fraction includes dead or inaccessible volume.
Limitations
No hourly peak, water age, treatment, fire flow, structural, seismic, freeze, overflow or pressure analysis is included.