Blend effect, contamination, and adulteration are three different problems

Ethanol is hygroscopic — it actively absorbs moisture from its surroundings — and is a stronger solvent than pure petrol. Past a saturation point (commonly cited around 0.5% water by volume), the ethanol-water mixture separates from the petrol and settles at the bottom of a tank — exactly where dispensing pumps draw fuel from. This is “phase separation.”

Ethanol moves mostly by rail and road tanker to OMC depots for blending — independent industry analysis of this value chain describes it bluntly as “largely unorganized”, with dedicated “Ethanol Blending Corridors” still only planned under the 2022 National Logistics Policy, not built industry value-chain analysis. Decades of international materials science explain why ethanol generally isn’t piped through ordinary petroleum infrastructure in the first place: chloride, water, and pH together drive stress corrosion cracking in carbon steel peer-reviewed materials research.

What has been done: OMCs replaced dispenser seals and washers with neoprene rubber; testing frequency has increased (water-ingress checks 8–12 times a day at 87,000+ outlets, per the Ministry). What hasn’t: no confirmed nationwide audit or certification programme for underground storage tanks built for straight petrol; no region-specific response despite documented higher risk in coastal and high-rainfall areas; and no published framework for who compensates a motorist when contaminated fuel — not the blend itself — causes damage.

E20 is marketed as a green fuel, and the tailpipe story genuinely supports that: ethanol’s oxygen content helps petrol burn more completely, cutting carbon monoxide by up to 50% in two-wheelers and 30% in four-wheelers compared with pure petrol. But that is only the part of the story that happens inside the engine. The rest of it — growing the feedstock, running the distillery, and disposing of what’s left over — carries a separate set of costs that rarely make it into the “green fuel” framing.

Industry figures for water use focus narrowly on the distillery itself: a 100 KLPD plant recycles most of its process water and draws roughly 4 litres of fresh water per litre of ethanol produced. That figure excludes the water used to grow the crop in the first place. Sugarcane needs 1,500–2,500mm of water spread across a growing season, and independent estimates put the total water footprint of sugarcane-based ethanol at 2,500–3,600 litres per litre of fuel, with rice-based ethanol running even higher. The government disputes the highest circulated figures (claims of 10,000 litres per litre) as conflating the entire irrigation footprint of a food crop grown under MSP procurement with the fuel-production step specifically — a genuine methodological dispute, not a settled number either way.

The Central Pollution Control Board ranks sugar mills and distilleries among India’s 18 most polluting industries, third by wastewater volume after pulp/paper and chemicals. Untreated spent wash (vinasse) blocks sunlight in rivers and ponds, killing aquatic life, and contaminates groundwater when it’s applied to land without treatment.

The regulatory answer is Zero Liquid Discharge (ZLD): every grain or molasses distillery is required to run its effluent through multi-effect evaporators and condensate polishing before it can get an operating clearance, recovering the water for reuse and turning the residual solids into boiler fuel or compost — a genuinely circular system when it’s built and monitored correctly. The gap is enforcement: effluent-treatment infrastructure hasn’t scaled at the same pace as production capacity, and documented cases of non-compliant treatment systems in more than one state have led to regulatory and legal action — enforcement that remains inconsistent across state pollution control boards.