Chemical quality of ground water in the State is assessed on a regular basis from the water samples collected from a network of wells, tapping shallow aquifers. The sampling is done during the pre-monsoon season. Quality of Ground water from deep aquifers is also determined from the samples collected during exploratory drilling. Chemical quality of ground water is also assessed for an area where detailed surveys are conducted for reappraisal of ground water resources.

Electrical conductivity of ground water ranges from 400 to 13000 micro Siemens / cm at 25 deg. C. with 80% of samples within the permissible limits for drinking purpose. In certain areas, fluoride content exceeds the permissible limit of 1.5 mg / l and the value reaches upto 10.4 mg/l. Contamination of ground water due to high fluoride content is due to the presence of fluoride bearing minerals in rocks.

Nitrate content in ground water is oberved to be higher than the permissible limit in 30% of the samples. Its presence is mostly due to anthropogenic influence, mostly due to sewerage. Higher usage of fertilisers also contributes to the nitrate pollution in ground water.

Owing to the depositional environment of the sediments in the coastal and deltaic plains, ground water is saline in most of the aquifers except along the old river courses (paleo channels) and in the shallow lenses of levees. Exploration down to 600 m in the coastal and deltaic plains of Guntur, Krishna and West Godavari districts has not revealed aquifers with fresh waters.

Ground water is also saline in in-land areas covered by black soils in the districts of Kurnool and Anantapur.

Ground water pollution due to industrial effluents is observed during special investigations in Patancheru, Jeedimetla areas of Hyderabad and in Visakhapatnam industrial areas.