Alert: Alarming level of nitrate levels found in groundwater of 440 districts in India

The Central Ground Water Board (CGWB), in a report, revealed an alarming level of nitrate levels in groundwater samples of 440 districts across India, with 20 per cent of them exceeding the permissible concentration. As much as 9.04 per cent of samples had fluoride levels above the safe limit, while 3.55 per cent showed arsenic contamination, the ‘Annual Groundwater Quality Report – 2024’ unravelled. 

A total of 15,259 groundwater monitoring locations were selected nationwide to assess groundwater quality. Out of total, 25 per cent of the wells, identified as vulnerable to contamination based on BIS 10500 standards, were chosen for detailed analysis. Groundwater quality was sampled at 4,982 trend stations during pre-monsoon and post-monsoon periods to assess the impact of seasonal recharge on groundwater quality.

The report has revealed that 20 per cent of water samples exceeded the nitrate limit of 45 milligrams per liter (mg/l), the threshold set by the World Health Organisation (WHO) and Bureau of Indian Standards (BIS) for drinking water. Nitrate contamination is a significant environmental and health concern, particularly in agricultural regions using nitrogen-based fertilizers and animal waste.

Rajasthan, Karnataka, and Tamil Nadu had over 40 per cent of samples above the limit while there was high contamination in samples from – Maharashtra at 35.74 per cent, Telangana at 27.48 per cent, Andhra Pradesh at 23.5 per cent and Madhya Pradesh at 22.58 per cent.  Uttar Pradesh, Kerala, Jharkhand and Bihar reported lower percentages.

In Arunachal Pradesh, Assam, Goa, Meghalaya, Mizoram and Nagaland, all samples were within safe limits.

A total of fifteen districts including Barmer and Jodhpur in Rajasthan; Wardha, Buldhana, Amravati, Nanded, Beed, Jalgaon, and Yavatmal in Maharashtra; Rangareddy, Adilabad and Siddipet in Telangana; Villupuram in Tamil Nadu; Palnadu in Andhra Pradesh; and Bathinda in Punjab have been identified as the most affected by high nitrate levels in groundwater.

In states like Rajasthan, Madhya Pradesh, and Gujarat, nitrate levels have remained stable since 2015.  However, Uttar Pradesh, Tamil Nadu, Andhra Pradesh and Haryana showed increasing contamination from 2017 to 2023, the CGWB said.

The report further said fluoride concentrations exceeding the permissible limit are a major concern in Rajasthan, Haryana, Karnataka, Andhra Pradesh, and Telangana.

Elevated arsenic levels (more than 10 parts per billion) were found in several states, particularly in the floodplains of the Ganga and Brahmaputra rivers, including regions of West Bengal, Jharkhand, Bihar, Uttar Pradesh, Assam, and Manipur, as well as areas in Punjab and Rajnandgaon district in Chhattisgarh.

Long-term exposure to fluoride and arsenic contaminants can have severe health consequences, including fluorosis (from fluoride) and cancer or skin lesions (from arsenic).

Forty-two per cent of samples with uranium concentrations exceeding 100 ppb (parts per billion) came from Rajasthan, and 30 per cent from Punjab, indicating regional hotspots of uranium contamination, the report said. Chronic exposure to uranium can lead to kidney damage.