Why STP Compliance Varies by State
India's Central Pollution Control Board (CPCB) sets baseline effluent discharge standards, but individual State Pollution Control Boards (SPCBs) — such as MPCB (Maharashtra), GPCB (Gujarat), DPCC (Delhi), HSPCB (Haryana), KSPCB (Karnataka), and TNPCB (Tamil Nadu) — can and often do impose stricter local limits, additional monitoring requirements, or specific technology mandates based on local water body sensitivity and industrial density.
This means a facility with identical operations in two different states may face different compliance obligations — which is why "just meet CPCB norms" is not always sufficient.
Common Parameters Every STP Must Meet
| Parameter | Typical CPCB Limit |
|---|---|
| BOD (5 days, 20°C) | ≤ 10–30 mg/L (depends on discharge point) |
| COD | ≤ 50–250 mg/L |
| TSS | ≤ 20–100 mg/L |
| Fecal Coliform | ≤ 100–1,000 MPN/100mL for reuse/land disposal |
| pH | 5.5–9.0 |
Note: exact limits depend on discharge point (inland surface water, land for irrigation, public sewer, or marine coastal) and the specific state's notification. Always confirm current limits with your local SPCB before design finalization — norms are periodically revised.
What Tends to Differ State-to-State
- Mandatory real-time monitoring: Several states (including Maharashtra and Delhi) now mandate Online Continuous Effluent Monitoring Systems (OCEMS) with direct SPCB data feed for STPs above certain capacity thresholds.
- Reuse mandates: Some states/urban local bodies mandate treated STP water reuse for flushing/gardening in new residential complexes above a certain unit count.
- Zero Liquid Discharge (ZLD): Certain industrial zones and water-stressed regions require ZLD compliance, which goes well beyond standard STP/ETP discharge norms.
- Consent renewal frequency and documentation: Varies by state; some SPCBs require more frequent lab reports and self-monitoring submissions than others.
Staying Audit-Ready
Regardless of which state you operate in, three things consistently keep facilities out of trouble during SPCB inspections:
- Properly sized equipment — under-capacity blowers, membranes, or dosing systems are the most common root cause of non-compliance, not operator error.
- Calibrated, working flow meters — inlet/outlet metering is now expected at most inspections; a non-functional flow meter is itself often flagged as a violation.
- Documented maintenance records — AMC logs, lamp replacement records (for UV systems), and membrane cleaning logs demonstrate ongoing compliance effort, not just point-in-time test results.
QuaSys Inc. supplies STP/ETP equipment engineered to meet these compliance parameters across India, along with calibrated flow meters for monitoring compliance. For help specifying equipment to your state's exact norms, contact our team or call +91 95408 15659.
