Unit CGWA number respect Purpose periods monsoon borehole May/June November location accuracy diameter 50 meters Pizometer inclusion mean level compliance second one centimeters coordinates regulations tapped zone pumping well water levels reduced level 4 to 6 inches water pressure identification considerations piezometer site allegianceindia specific depths piezometer/tube different depths minimum distance assembly details piezometric head Quality analysis NOC requirements observation wells four to six hours general guidelines NABL-approved labs specific guidelines GWD Analytical Labs Groundwater quality accurate monitoring groundwater behavior standard referencing multiple piezometers Measurement frequency Allegiance Enterprise surrounding tube wells permanent display board piezometer installation Installation Guidelines aquifer characteristics Water level measurements Borewell Drilling Service shallow groundwater regime Allegiance Water Management The Central Ground Water Authority National Hydrograph Monitoring System