Online Continuous Effluent Monitoring Systems — OCEMS — measure the parameters that define your compliance status around the clock, and push readings straight to your pollution control board's server. Quarterly lab sampling used to be the norm; for a large group of industries, it no longer is.
Who has to install one
CPCB's applicability list covers 17 categories of highly polluting industries — thermal power, cement, steel, pulp and paper, and pharmaceuticals among them. If your facility falls into one of these categories and was commissioned on or before 28 February 2017 without OCEMS connectivity, CPCB has directed State Pollution Control Boards to issue closure orders. This is already an enforceable gap, not a future deadline.
The checklist: what "compliant" actually means
- Correct parameters for your sector. Textile units typically monitor pH, BOD, COD, TSS, chromium and flow. Pharmaceutical facilities add arsenic to that list. Confirm your sector's exact required parameter set — it isn't one-size-fits-all.
- Accuracy within tolerance. COD and BOD readings must stay within ±10%, pH within ±0.2, and TSS within ±10%.
- Calibration on schedule. Initial calibration at installation, monthly in-house calibration checks, and annual performance testing by an NABL-accredited lab.
- Data uptime above 85%. Connectivity gaps are themselves a compliance issue — not just a data quality problem.
Why the annual NABL calibration step matters most
Of everything on this checklist, the annual performance test by an NABL-accredited lab is the one most factories underestimate. In-house monthly checks catch drift early, but the accredited annual verification is what actually holds up as evidence if your data is ever challenged — an uncalibrated or informally-verified system can technically be transmitting data 24/7 and still fail an audit if it can't prove accuracy.
Need OCEMS calibration or verification support?
Rispri Laboratory is a NABL-accredited testing lab — we handle the accuracy verification and calibration checks that keep your OCEMS data defensible, not just connected.
Explore Water & Wastewater TestingFrequently asked questions
Does OCEMS replace the need for periodic lab testing entirely?
No. OCEMS provides the continuous, real-time compliance record, but calibration and performance verification still require periodic accredited lab testing — the two work together, not as substitutes for each other.
What counts as a "highly polluting" industry under this rule?
CPCB's 17-category list includes thermal power, cement, steel, pulp and paper, pharmaceuticals, and other sectors with significant effluent or emission loads. If you're unsure whether your sector is on the list, that's worth confirming directly rather than assuming either way.
What happens if our data uptime falls below 85% in a given month?
Sustained connectivity gaps are treated as a compliance issue in their own right, separate from whatever the underlying effluent quality actually was — meaning a system with excellent effluent quality but poor uptime can still trigger enforcement action.
Sources: Team One Biotech, CPCB official OCEMS guidelines. This article is for general guidance and isn't a substitute for confirming your specific facility's requirements with CPCB or your State Pollution Control Board.