Petrol pump owners flagged moisture contamination concerns after nationwide rollout of E20 ethanol-blended petrol.
Officials said E20 meets BIS standards, rejecting claims of contamination unique to ethanol-blended fuel.
Industry raised concerns over storage, while government cited safeguards and infrastructure upgrades for E20.
India has completed the nationwide adoption of E20 petrol, meeting its target of 20 per cent ethanol blending well before the 2030 deadline.
However, three petrol pump owners flagged a fresh challenge with E20 fuel, which contains 20% ethanol and 80% petrol - regarding water contamination during monsoons and in coastal areas. The issue stems from the hygroscopic nature of ethanol, which attracts and holds water molecules from the surrounding environment.
An industry expert told The Hindu, "The underground tanks that store fuel often have some amount of water due to ingress during rains or moisture or condensation or from the fuel tanker that brings petrol to the petrol pump."
When the water content in the entire E20 stock in underground tanks exceeds 0.5%, ethanol binds with water because of its affinity for water. This results in phase separation, where the water-ethanol mixture settles at the bottom of the tank while the petrol forms a separate layer above.
As the dispensing unit draws fuel from the bottom of the underground tank, some vehicles may end up being dispensed this water-rich mixture instead of E20. "As a result, vehicles may not start, or breakdown after a distance. We come to know about contamination only when such customers come to us with complaints," one of the owners told The Hindu.
Existing underground storage tanks were designed for conventional petrol, not higher ethanol blends. In coastal areas, sub-soil water can further contaminate E20 stock if the seals on the underground tanks are not properly in place.
One of the petrol pump owners expressed fears that underground tanks and pipelines made of mild steel could become more susceptible to corrosion because of ethanol's tendency to absorb water, potentially adding to fuel contamination.
Oil marketing companies (OMCs) have, however, replaced seals and washers in petrol dispensing units with neoprene rubber in preparation for E20.
The Ethanol Blended Petrol (EBP) Programme is one of India's key energy initiatives. It aims at improving energy security, supporting farmers and reducing environmental impact through greater use of domestically produced renewable fuel. Several concerns were raised about E20 fuel as India mandated all petrol pumps to stock and supply it as the standard fuel.
The Federation of Automobile Dealers Associations (FADA) had earlier fact-checked the claim that E20 causes water contamination unique to ethanol-blended petrol, calling it "misleading".
FADA stated that ethanol's moisture absorption is a known property accounted for in fuel standards, storage and vehicle design. FADA stated, "India's E20 meets stringent BIS specifications."
The Ministry of Information and Broadcasting also stated that the entry of water into the fuel tank is undesirable for any fuel, whether ethanol-blended or otherwise. Modern vehicles are equipped with design features and safeguards to prevent water entry into fuel tanks, the ministry stated.
The Ministry of Petroleum and Natural Gas issued a detailed clarification on the programme through a press release on June 23, 2026, addressing various concerns. Automobile manufacturers also issued their own clarifications during a press conference held on July 4, 2026.
