Water Contamination in Fuel: The 3 Types of Water to Look Out For

Mon, Sep 11, 2023

A build-up of moisture and water in stored fuels is inevitable with the bio content in today’s diesel. Even if there is low water content when fuel is first put into storage, vapour and condensation can be absorbed in a fuel tank and result in water contamination in diesel.

Microbiological growth, or diesel bugs can grow from just a few small droplets, which could even come from rainwater if a tank has loose filler caps, worn seals, torn gaskets, and broken tank breather pipes. However, water in fuel does not just settle as a layer at the bottom of a tank like most people assume, there are in fact 3 ways water can be found in fuel, which are known as free water, suspended water, and emulsified water.

3 Types of Contaminated Water in Diesel Fuel

  1. Free water in diesel fuel is visible as a layer of separated water in the fuel tank that has completely separated from the fuel and sunk to the bottom of the tank. This creates a layer of visible water under the diesel fuel. This is where diesel bugs often grows and can put your equipment, vehicles, and engines at risk of costly downtime and damage.
  2. Suspended water (sometimes known as bound water) is where the water has bound to the fuel molecules and mixed with the fuel making it appear cloudy. As the diesel becomes so full of suspended water that it can hold no more (as water is heavier than diesel) it starts dropping to the bottom of the tank and becomes free water.
  3. Emulsified fuel is where the water in diesel fuel becomes completely emulsified turning the diesel into a milky opacity. There is almost no separation between the fuel molecules and water content. It can occur when fuel passes through pumps and filters, under pressure changes, agitation, and heavy cavitation.
3 Types of Water in Fuel

How to Remove Water in Diesel Fuel

diesel water contamination

By removing water in diesel, you are preventing water contamination in fuel and stopping the symptoms that go on to cause severe damage to your equipment, engines, and vehicles. Water can be removed from fuel in 3 ways.

Tank Filters

Fuel tank filters are fitted on the outlet of a diesel fuel tank to remove water before it enters the equipment it is fuelling. They do not remove water from the tank, however, just stop the free water in the fuel from being dispensed. They have no effect on suspended or emulsified water in fuel.

Fuel Polishing

Fuel polishing is an advanced cleaning process that removes water, sludge and microbial contamination through filtration and circulation. This service is usually undertaken by a professional and involves removing the fuel from the tank and passing it through highly efficient filters that remove contamination down to the EN590 quality standards of diesel fuel. This is recommended as part of an annual fuel maintenance programme to ensure fuel is kept at ISO standards.

Tank Water Absorbers and Tank Dryers

Aquafighter product range

Tank Dryers remove contaminated water in fuel, reducing the damaging impact that water has on machinery and vehicles. Tank Dryers contain highly absorbent silica gel, which when lowered into a tank absorbs a small amount of water, which means it may not be suitable for large fuel tanks.

A tank water absorber usually only removes free water from the bottom of a fuel tank, but Aquafighter is the only fuel tank water absorber on the market that removes suspended and emulsified water too! This provides a complete yet cost effective solution for water contamination, eliminating the problems that cause engine and equipment damage. Unlike other fuel tank water absorbers, the Aquafighter reduces the water content levels down to less than 75ppm, meeting and exceeding the EN590 diesel fuel standards of 200ppm. Using tank absorbers is an effective way to keep tanks free of water in between fuel polishing intervals.

Act on your water in diesel today and protect and preserve your fuel. View our full range of Aquafighter products.

Ready to take control of the water in your fuel?

CTS is the UK agent for Aquafighter water absorber; a range of high-quality fuel tank water absorbers that remove both free and emulsified water, ensuring your fuel is water-free all the time.