Diesel microbial contamination

Diesel fuel is not a sterile environment. Every diesel tank forms its own biological system where bacteria, yeasts and moulds can survive and multiply. Microorganisms are naturally present in the environment and enter fuel systems via air, water and fuel. 

Why do microbes grow in diesel fuel?

Microbial growth occurs when the following conditions are present:

• water

• nutrients (hydrocarbons)

• suitable temperature

Modern diesel fuels contain bio-components that bind water, making water separation more difficult and creating favourable conditions for microbial growth.

Consequences of microbial contamination

Microorganisms form biomass (biofilm) that can:

• clog fuel filters

• restrict fuel flow

• damage injectors

• cause equipment failures and downtime

Sulphate-reducing bacteria can also cause rapid and severe corrosion, particularly in low-use fuel systems.

Removal and control

Existing biomass must be removed mechanically or by effective circulation cleaning. Additives alone cannot remove established biofilm. After cleaning, controlled biocide treatment helps prevent recontamination.

Prevention

• maintain tank integrity

• monitor fuel condition regularly

• clean tanks professionally when required

• apply additives only when justified and in a controlled manner

A documented and preventive approach ensures long-term fuel system reliability.