Ethanol contamination in fuel

Notes

• E20 fuel (20% ethanol blend) exhibits hygroscopic properties, meaning it has a high affinity for water.
• Phase separation occurs when water content in E20 exceeds 0.5%, causing a water-ethanol mixture to settle at the bottom of storage tanks.
• Existing underground fuel storage tanks, often designed for conventional petrol, are susceptible to water ingress via condensation, rain, or sub-soil seepage, particularly in coastal areas.
• Contaminated fuel can cause fuel injector malfunction, fuel pump failure, poor driveability, and engine damage.
• Mild steel storage tanks and pipelines face increased corrosion risks due to the water-absorbing nature of ethanol.
• Current mitigation protocols include checking tanks for water using water-finding paste (dipstick) three times daily, with increased frequency during monsoons.
• Oil Marketing Companies (OMCs) are responsible for draining contaminated fuel using hand pumps, though dealers report bearing the financial burden of discarded stock.
• Consumer protection disputes are emerging regarding fuel quality, with recent legal interventions directing replacements for vehicles affected by fuel-related engine issues.

Part of a longer story

This is day 7 of 21 in Safety and implementation of E20 ethanol-blended fuel, which has been running since 5 July 2026. Reading it whole is usually worth more than reading today alone — the exam asks how something developed.

• Revised CAFE III fuel efficiency norms Before
• E20 fuel transition and vehicle issues After
• The whole story 21 entries