Water Quality Testing: Parameters, Standards and Common Failures
Water testing serves two masters: the regulator, who cares whether discharge meets consent standards, and the operator, who needs to know whether the plant is working. A well-designed sampling programme answers both.
Drinking water: IS 10500
Potable water supplied at a premises is assessed against IS 10500, covering physical parameters, chemical parameters including hardness, fluoride, nitrate and heavy metals, and microbiological safety.
In Bangalore, borewell-dependent campuses should test at least annually, and after any change in source or treatment.
Treated sewage and effluent
Treated water is assessed against the discharge or reuse standard written into your consent. Common parameters are pH, BOD, COD, total suspended solids, oil and grease, ammoniacal and total nitrogen, phosphate and faecal coliform.
Sampling both inlet and outlet is what turns a compliance test into a performance measurement, because removal efficiency, not outlet concentration alone, tells you how the plant is behaving.
Sampling practice determines validity
Sample containers, preservation, holding time and chain of custody are prescribed by parameter. A correctly analysed sample that was wrongly collected produces a confidently wrong number.
- Composite sampling for variable flows, grab sampling for spot checks
- Correct preservative and temperature for each parameter group
- Holding times respected between collection and analysis
- Sampling point recorded unambiguously
Reading a failed result
High BOD and COD with low suspended solids often points to biological underperformance — sludge age, aeration or nutrient balance. High suspended solids with acceptable soluble load points to clarifier or filtration issues. High ammoniacal nitrogen suggests incomplete nitrification.
Hydraulic overload is the most common underlying cause across all of these in Indian STPs, particularly where occupancy has grown past the design basis.
Ground water monitoring
Where waste storage, effluent handling or landfilling occurs, ground water monitoring wells upgradient and downgradient of the source provide early warning of leakage and are frequently a clearance condition.
Frequently asked questions
How often should treated effluent be tested?
Monthly outlet testing is common practice and is often written into consent conditions, with more frequent internal testing where the plant is close to its limits.
Which laboratory should do the analysis?
A NABL-accredited laboratory for the relevant parameters. Accreditation scope matters, since a laboratory may be accredited for some parameters and not others.
Can treated sewage be reused?
Yes, and reuse for flushing, gardening and cooling is widely practised and often mandated in Bangalore developments. Reuse standards differ from discharge standards and should be confirmed against the intended application.
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