Work out reservoir storage capacity instantly with clear inputs, formula shown and shareable results.
Service reservoir storage has three components: balancing storage to absorb the difference between steady supply and variable demand, typically a third to a half of daily demand; a fire-fighting reserve set by the required flow and duration; and an emergency reserve for supply interruption.
Storage capacity
Total = average daily demand x (balancing days + emergency days) + fire reserve
Fire-fighting storage and flow requirements are set by the fire authority and building regulations. Confirm requirements before finalising reservoir capacity.
Yes. Excess storage lengthens water age, allowing chlorine residual to decay and disinfection by-products, nitrification and taste problems to develop. Turnover should be at least once every few days.
From the required fire flow for the largest risk in the zone and the duration the fire authority specifies — commonly 30 litres per second for two hours in residential areas, far more for industrial risks.