Water Supply

Rapid Sand Filter Area

Filter bed area for a rapid (gravity) sand filter. Includes the conventional rule-of-thumb for number of units N ≈ 1.2·√Q (Q in MLD).

Formula
A = Q / v;  N ≈ 1.2 · √Q (Q in MLD)

Typical RSF rate: 4–7 m/hr; up to 10 m/hr for high-rate filters.

Resultlive
Total filter area, A
33.333
Recommended no. of units
3
Area per unit
11.111
Bed dimensions (≈ L × W)
3.73 × 2.98m
Backwash water demand
160m³/day
Reference: Conventional design: filtration rate 4–7 m/hr (CPHEEO Manual). N ≈ 1.2·√Q (Q in MLD) per common practice.