Water Quality Assessment of the Central Himalayan Lake, Nainital

Table 1

Drinking water quality standards, units, analytical method, and recommending agencies (source: [8–10]).

Water quality	Unit	Analytical method	Indian standards (desirable) and recommended agencies
pH	pH unit	pH meter	6.5–8.5 (BIS/ICMR)
Turbidity	NTU	Turbidity meter	5 (BIS)
Dissolved oxygen	mg/L	DO meter	5 (ICMR)
Electrical conductivity	µs/cm	Conductivity meter	300 (ICMR)
Total dissolved solid	mg/L	TDS meter	500 (BIS)
Total suspended solid	mg/L	Gravimetric	500 (WHO)
Temperature	Degree Celsius	Portable thermometer	—
Biochemical oxygen demand	mg/L	Winkler azide method	5 (ICMR)
Total hardness	CaCO3 mg/L	Titrimetric	300 (BIS/ICMR)
Total alkalinity	CaCO3 mg/L	Titrimetric	120 (ICMR)
Chloride	mg/L	Argentometric	250 (BIS/ICMR)
Sodium	mg/L	Flame photometer	<20 (WHO)
Potassium	mg/L	Flame photometer	10 (WHO)
Phosphate	Microgram/L	UV spectrophotometer	—
Lead	mg/L	Atomic absorption	0.05 (BIS)
Copper	mg/L	Atomic absorption	0.05 (BIS)
Iron	mg/L	Atomic absorption	0.3 (BIS)
Zinc	mg/L	Atomic absorption	5 (BIS)

BIS: Bureau of Indian Standard, WHO: World Health Organization, and ICMR: Indian Council of Medical Research.