Interactive Calculator · 2026
Equalization Tank Volume Calculator
Size the equalization (buffer) tank for a sewage treatment plant. Enter the average daily flow and the detention time, and get the required tank volume in m³ — the buffer that smooths peak flows before treatment.
Tank volume grows with detention time — your 8h choice highlighted
Your flow
The average volume of sewage reaching the plant per day.
Hours of average flow the tank holds to buffer peaks — typically 4–12 h.
How this is calculated
- Average hourly flow = daily flow ÷ 24 = 200 ÷ 24 = 8.3 m³/hr.
- Tank volume = average hourly flow × detention time = 8.3 × 8 = 66.7 m³.
- % of daily flow = tank volume ÷ daily flow × 100 = 33.3%.
Indicative sizing for concept planning. A detailed design must also fix the peak-flow factor, mixing and aeration, freeboard and geometry — confirm with a qualified consultant before procurement.
Related Guides — Deep-dive reading
Equalization Tank in an STP: Purpose, Working & Sizing Explained
The buffer tank that catches the morning rush and the midnight trickle and hands the rest of the plant one calm, steady flow — why flow equalisation matters, how the tank also mixes and pre-aerates, and the rules of thumb for sizing it.
Sewage Treatment PlantsHow to Size an STP: A Step-by-Step Method (With Worked Example)
The complete sizing methodology for a domestic sewage treatment plant — from headcount and LPCD to sewage generation, peak flow and tank-by-tank volumes — worked end to end with an Indian apartment example.
Sewage Treatment PlantsUnderstanding Hydraulic Retention Time (HRT) in STPs: The Complete Guide
What hydraulic retention time really means, how it sets the size of your reactor and the quality of your treated water, typical HRT figures for ASP, MBBR, SBR and UASB, and why HRT and SRT are two different clocks you must not confuse.
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