<p>Supplementary table 1 Water quality parameters assessed, instruments and methods used , with model no., country, linearity ranges, detection limits or resolution* and accuracy</p><p>Parameter Method/Instrument Country Linearity range Detection Accuracy limit/Resolution*</p><p>Temperature Edutek digital thermometer TTX 483-P India -50 °C to 150 °C 1°C* ±0.8°C Conductivity Milwaukee conductivity tester C62 S48228 Portugal 0 to 1999 uS cm-1 1 µScm-1* ±2% TDS Hanna TDS meter Hi 98302 Mauritius 0-2000 ppm 1 ppm* ±3% pH Milwaukee pH meter pH 600 Romania 0-14 0.1 pH* ±0.1 Turbidity Nephlometer CL 52 D India 0-1000 NTU 0.1NTU* ± 2% DO Titimetric - - - - - BOD Titrimetric BOD Incubator India 5 – 60 °C - - Webcon (Omni Xtra) COD Spectrophotometer Hitachi U-2900 UV-Vis Japan 1.16-70 mg l-1 1.16 mg l-1 ±0.002 Hardness Titrimetric - - - - - Alkalinity Titrimetric - - - - - Phosphate Spectrophotometer Hitachi U-2900 UV-Vis Japan - - ±0.002 Nitrate Spectrophotometer Hitachi U-2900 UV-Vis Japan 0.1-2 mg l-1 0.1 mg l-1 ±0.002 Cr AAS Analyst 800, Perkin USA - 0.006 mg l-1 - Elmer Cu AAS Analyst 800, Perkin USA - 0.003 mg l-1 - Elmer Cd AAS Analyst 800, Perkin USA - 0.002 mg l-1 - Elmer Pb AAS Analyst 800, Perkin USA - 0.0l mg l-1 - Elmer Zn AAS Analyst 800, Perkin USA - 0.001mg l-1 - Elmer</p><p>AAS-Atomic Absorption Spectrophotometer </p>