E-Paper
High fluoride found in Delhi’s groundwater
High fluoride levels in the water, when consumed, can lead to dental fluorosis and have been linked to bone damage and skeletal fluorosis
The Delhi government has informed the National Green Tribunal (NGT) that it has found high fluoride levels — beyond permissible standards — in 58 tubewells across the city after collecting samples from 1,256 tubewells.
In a submission to the tribunal, the government said it already issued directions to the Delhi Jal Board (DJB) to either stop the supply of water from these tubewells or to utilise water for all other purposes except drinking.
The checks were carried out, following directions issued by NGT on December 12, 2023, asking states and Union territories to test groundwater samples and to inform about the presence of arsenic or fluoride in them. The tribunal had taken suo-motu cognisance of a report in Hindustan (Hindustan Times’ sister publication) on November 30 which was titled “Arsenic found in groundwater in 25 States, fluoride in 27 States: Govt”.
The Delhi government said it carried out testing at 1,256 tubewells for both arsenic and fluoride. While no arsenic was found in 122 samples in north, central and west Delhi, testing kits will be needed to assess samples for arsenic in remaining zones in Delhi.
For fluoride, it said 58 samples out of the 1,256 had levels higher than the permitted 1mg/litre standard. The highest (34 samples) came from the Bawana area, followed by 11 from the Nangloi area.
These tubewells all come under DJB and are used to supply fresh water to parts of the city. Typically, DJB uses them to augment the city’s water supply by mixing this water with fresh water coming from Yamuna and other sources.
Levels of over 1.5mg/l are generally enough to cause the enamel to start staining, while levels of over 5mg/l can cause bone stiffness and damage in the long run.
The list of areas where high fluoride was detected, included Badarpur, Rajouri Garden, Govindpuri, Bawana, Narela, Dichaon Kalan, Nangloi, Paprawat, Jharoda, Kakrola, Khera Khurd, Shakarpur and Fateh Nagar.
High fluoride levels in the water, when consumed, can lead to dental fluorosis and have been linked to bone damage and skeletal fluorosis. It can also lead to arthritis and calcification of tendons and ligaments.
“The Delhi Jal Board has a quality wing and random groundwater samples are collected from different tubewells for checking the content of fluoride and arsenic. DJB has (already) taken precautions and issued directions to the maintenance divisions of the DJB to either stop supply from such tubewells or to utilise the water for all other purposes except drinking,” said the submission.
The Delhi government further sought a time of five months to test samples for arsenic in the remaining zones in Delhi. “...the tribunal may please grant some time for carrying out the testing of the contents of arsenic in the samples collected from different tubewells existing in various areas of Delhi. We will need time of around five months for the procurement of kits and its allied units for such testing...,” it added.
Experts said that in most cases, fluoride makes the water alkaline. “Fluoride forms naturally underground and there are no anthropogenic sources involved. In most cases, the fluoride makes the water more alkaline. There is a greater risk of such water in the outer parts of Delhi, as this groundwater is often consumed through handpumps. In such a case, there is a gradual health risk if it is consumed over time,” said Shashank Shekhar, professor at the department of geology, Delhi University, who carried out a study on fluoride in Delhi’s groundwater in 2016 and found 34% of the 44 samples collected had high fluoride levels.
