UF Flux Sizing Calculator
Estimate the ultrafiltration grade you need from daily water demand, source water quality and operating hours - then send the resulting specification to our engineers in one tap. Estimates use conservative derating factors; final sizing is confirmed against your water analysis.
Design flow = demand ÷ hours ÷ source factor × application margin. RO pre-treatment duty sizes the UF at 1.5× the RO feed requirement.
Recommended configuration
~1,875 L/h design flow
- H-1 whole-house UF module, 3,000 L/h grade (304 stainless, PVDF or PVC element)
- RO stage: Sized at 1.5x the RO feed requirement so cleaning intervals stay long; the RO stage itself is specified against your own element.
Expected UF element life on this source: up to 24 months with routine backwash; the stainless housing is permanent.
How we size ultrafiltration
Membrane systems are sized by sustained flux, not peak thirst. Three adjustments turn a daily water number into real equipment: the duty cycle (how many hours a day the plant actually runs), a source-water derating factor, and an application margin for cleaning downtime and future load.
| Source water | Flux factor | Element life |
|---|---|---|
| Municipal (treated) | 100% of rated flux | up to 24 months |
| Bore / well | 85% of rated flux | up to 18 months |
| River / reservoir / secondary effluent | 70% of rated flux | up to 12 months |
Why RO pre-treatment uses a 1.5× margin
A UF stage feeding reverse osmosis must deliver the RO feed flow while part of the membranes sit in backwash. Sizing the UF at about 1.5× the RO requirement - or splitting it into two modules that backwash each other, the arrangement used on coin-operated water vending machines - keeps the RO train running without a dedicated cleaning pump.
This tool is an estimate. Send a water analysis or a worst-case description via the buttons above and we will confirm the grade, manifold and pre-treatment train for your duty.