COD, BOD5 and TSS: what the effluent numbers mean
Three numbers decide whether treated wastewater can be reused. Here is what each one tells you.
Our wastewater units are guaranteed to deliver COD below 80 mg/L, BOD5 below 30 mg/L and TSS below 10 mg/L. These three parameters are the core of most reuse and discharge permits.
COD, chemical oxygen demand
COD measures everything in the water that can be oxidised chemically, both biodegradable and persistent organics. A low COD means the plant has removed most of the organic load.
BOD5, biochemical oxygen demand
BOD5 measures the oxygen bacteria consume over five days. It tracks the biodegradable fraction, the part that would deplete oxygen in a river or cause odour in storage. Below 30 mg/L, effluent is stable enough for irrigation and many industrial uses.
TSS, total suspended solids
TSS is the particulate matter you can filter out. Low TSS protects drip emitters, pumps and downstream filters, and makes disinfection far more effective.
Why guarantees matter
Permits and reuse contracts are written in these numbers. When you compare offers, ask for guaranteed values at the design flow and load, and the sampling method behind them.