The tank is sized to catch one design-storm day from the roof. Paved areas usually go to a recharge pit rather than the tank. Runoff coefficients are typical values, so adjust them for your surfaces.
Roof yield / year–
Suggested tank–
Days of supply–
Recharge / year–
System roof → first flush → tank → overflow to recharge
Numbers per year unless stated
| Item | Value | How |
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