Storm-event overflow calculator
Assume the tank may be full
For drainage and flood checks, authorities may require the tank to be treated as full unless a verified control strategy creates storage before storms.
Route overflow safely
The discharge point must account for erosion, icing, foundations, property boundaries, septic systems, slopes, public paths and the capacity of downstream drainage.
Planning estimate only: Verify local rainfall, product ratings, structural support, overflow, plumbing, water-quality and permit requirements.