A: When diesel fuel is stored it is easily contaminated. Even under the best conditions it should be cleaned or replaced after 6-12 months. Under less than perfect conditions, that may be considerably less. Here are some of the common contaminants:
Water: Diesel is hygroscopic which means it absorbs water from the atmosphere and from condensation.
Microbes and fungus: the combination of water and the carbon, oxygen, sulphur and trace elements in the diesel provide a perfect breeding ground for microbes and fungae which form a sludge in the diesel and on the sides of the tank.
Rust: Water causes corrosion of the tank resulting in rust particles in the diesel.
Particles: Dust, dirt and other particles build up and eventually block filters.
You may have heard of the ‘clean and bright test’ which is a visual inspection to see if fuel appears hazy or dark in colour. This is not enough. To know if your diesel fuel is contaminated it should be professionally lab tested for purity.
A: You are legally responsible for cleaning the diesel in your tanks at least once a year. If you don’t you are in direct contravention of the National and Provincial Fire Code, which could result in heavy fines and criminal liability.