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Mogden formula
You are here: Ofwat > Non-household consumers > Your water bill > How non-household customers are charged > Trade effluent charges > Mogden formula
Charges for trade effluent are based on the Mogden formula, which is
Charge per unit of effluent = R + [(V + Bv) or M] + B(Ot/Os) + S(St/Ss)7
where
R = reception and conveyance charge [p/m3]
V = primary treatment (volumetric) charge [p/m3]
Bv = additional volume charge if there is biological treatment [p/m3]
M = treatment and disposal charge where effluent goes to sea outfall [p/m3]
B = biological oxidation of settled sewage charge [p/kg]
Ot = Chemical oxygen demand (COD) of effluent after one hour quiescent settlement at ph 7
Os = Chemical oxygen demand (COD) of crude sewage one hour quiescent settlement
S = treatment and disposal of primary sewage sludge charge [p/kg]
St = total suspended solids of effluent at ph 7 [mg/litre]
Ss = total suspended solids of crude sewage [mg/litre]
