According to the CGWB report, except for a few places in the northern and western parts of Delhi, the fluoride concentration was found to be within the permissible limit of 1.5 micrograms per litre.
New Delhi: The Central Ground Water Board (CGWB) said in a report that groundwater in most parts of Delhi is saline in nature and nitrate concentration is high in groundwater in the northeastern parts of the capital. CGWB's Ground Water Yearbook 2021-22 states, "Chemical analysis of groundwater samples collected in May 2021 shows that nitrate content in groundwater was found to be within the permissible limit of 45 micrograms per litre in most parts of the state." However, the nitrate concentration is higher in the northeastern parts of Delhi."
It said that except for a few places in the northern and western parts of the city, the fluoride concentration was found to be within the permissible limit of 1.5 micrograms per liter in all other areas. According to the report, the electrical resistivity (EC) in the eastern parts of Delhi, especially the areas around the Yamuna plains and the Delhi Quartzite Ridge zone, was found to be within the acceptable limit of zero to 2,250 micro siemens per centimetre.
The electrical resistivity of a substance refers to the ability of that substance to oppose the flow of electric current. Salinity, a measure of the number of salts dissolved in water, is directly proportional to electrical resistivity. Areas that have an EC of more than 3,000 micro siemens per centimetre are high in chloride. Some of these localities include Sanjay Gandhi Transport Nagar (3,800), Bawana Water Treatment Plant (4,697) and Pusa (3,871).
The report said that a high concentration of iron (more than 1 mg per litre) was recorded in Rohini Sector 11, Nangli, Rajapura, Bhalswa Lake and Burari. It states that the quantity of uranium in Kanjhawala, Jaunti and Nizampur was more than the permissible limit (30 parts per billion).