Filter Area for a Target Loading Rate
The filter area needed for a target loading rate at the design flow.
Example
You enter
- Design flow (GPM) 800
- Target loading rate (gpm/ft²) 4
- Backwash rate (gpm/ft²) 15
You get
- Required filter area 200.0 ft^2
- Backwash flow 3000 GPM
Details, formula, and sources
area = flow / target loading. 800 GPM at 4 gpm/ft^2 needs 200 ft^2 of media; the backwash flow that area draws (15 gpm/ft^2 default) is reported and the loading band named. Answers 'how big a filter' instead of the rate from one area. AWWA general practice; the operator of record and the state primacy agency govern.
Required filter area (ft²) = design_flow / target_loading. Backwash flow = backwash_rate × area. Bands: rapid sand 2-5 gpm/ft², high-rate 5-8 gpm/ft².
Ten States Standards (Recommended Standards for Water Works), Great Lakes - Upper Mississippi River Board of State and Provincial Public Health and Environmental Managers, current edition by name. AWWA B100 / B130 (filter media) by name.
Ten States Standards licensed; principles free in published water-treatment texts.
Estimate. Operator of record and primacy agency govern.
Field names used by the API: flow_gpm, target_loading_gpm_ft2, backwash_rate_gpm_ft2, required_area_ft2, backwash_gpm
- Default backwash rate 15 gpm/ft² unless user suppliesTen States Standards typical