Interactive Calculator · 2026
Filter Sizing Calculator (PSF/ACF)
Size a pressure sand filter (PSF) or activated carbon filter (ACF) from flow and filtration rate. Enter the daily flow, the filtration (loading) rate and operating hours — get the vessel diameter every filter design starts from.
Flow & filtration rate
Total volume the filter must treat per day.
Hours the filter actually runs — sets hourly flow.
Loading rate across the media bed — typically 8–20 m³/m².hr for a PSF/ACF. Lower = larger, gentler filter.
How filtration rate drives filter area
Required filter area at each filtration rate for 10 m³/hr — a higher rate shrinks the filter but pushes the media harder.
Highlighted bar = your selected rate of 12 m³/m².hr
How this is calculated
- Design flow = flow ÷ operating hours = 200 ÷ 20 = 10 m³/hr.
- Filter area = design flow ÷ filtration rate = 10 ÷ 12 = 0.83 m².
- Vessel diameter = √(4 × area ÷ π) = √(4 × 0.83 ÷ π) = 1.03 m.
Indicative sizing for concept planning. A detailed design must also fix media depth, freeboard, backwash rate and vessel standard — confirm with a qualified consultant before procurement.
Related Guides — Deep-dive reading
Pressure Sand Filter (PSF) in an STP: How Tertiary Sand Filtration Works
The tertiary filter that catches the fine suspended solids clarifier settling leaves behind — how multigrade media filtration works, its filtration rate, backwashing, and why it sits just before carbon and disinfection.
Sewage Treatment PlantsRainwater Recharge Pit for Indian Homes: How It Works, Sizing, Filter Media, Distances and Maintenance
The soak-pit that puts rain back into the ground — how a rainwater recharge pit works, how to size it against your roof area and soil percolation, the boulder-gravel-sand filter media, the desilting chamber ahead of it, safe distances from foundation, borewell and septic, why it fails in clay, and how to keep it from choking.
PlumbingSTP for Shopping Malls: Mixed Loads, Big Reuse
Why a mall's wastewater is unlike any other building's — a punishing mix of food-court grease, washroom peaks and huge cooling-tower thirst — and how to size, site and choose an STP that turns all of it back into usable water in the basement.
Sewage Treatment PlantsRelated Tools — You may also find these useful
Air Requirement Calculator
Estimate the process air an aeration tank needs — enter flow, inlet BOD, O2 demand factor and transfer efficiency to get O2 demand and blower air in m3/day and m3/min.
STP CalculatorApartment STP Planner
Plan an apartment complex sewage treatment plant from flats and occupancy — get population load, sewage flow, recommended STP capacity in KLD, treatment technology and approximate space.
PlannerASP vs SBR Comparator
Weight seven criteria by importance to get a scored recommendation between the Activated Sludge Process and a Sequential Batch Reactor for your sewage treatment plant.
Comparator