AdBlue buyers' guide

The word AdBlue first entered our vocabulary in 2003. It had been coined as a trademark by the German automotive industry association, the VDA (Verband de Automobilindustrie). The VDA wanted a standard for a urea solution that was soon to be widely adopted by commercial vehicle manufacturers poised to comply with Euro-4 exhaust emission limits, which took effect for all new trucks registered from October 2006.

Since then, we have witnessed the birth of the AdBlue industry, the establishment of a supply chain and the development of all the paraphernalia to store, dispense and manage it. Originally, only around half the new trucks appearing on UK roads needed AdBlue. Some operators tried to steer clear of it altogether, aided by some manufacturers who tried holding back the tide in the UK. But that option soon disappeared as every heavy truck on sale uses AdBlue. Indeed, it's EGR (exhaust gas recirculation) that's falling out of favour as a growing number of manufacturers abandon the dual-process approach in favour of SCR-only engines.

We're now on the third version of Euro-6 (step C) which demands that the new emission levels are maintained for the first seven years, and that the truck fails to proceed at a feasible speed if they aren't. This, along with concern from bodies as diverse as the Traffic Commissioners and ACEA, the European vehicle manufacturers’ organisation, should gradually bring an end to the unscrupulous use of SCR defeat devices.




Although sometimes incorrectly described as a fuel additive, AdBlue should be kept well apart from diesel. It is more correctly described as a reagent and is the diet of choice for vehicles’ selective catalytic reduction (SCR) systems. When sprayed into a hot exhaust stream, AdBlue gives off ammonia gas that reacts with the SCR catalyst to convert NOx (oxides of nitrogen) in the exhaust gases into harmless nitrogen and water.

The generic description of AdBlue is AUS32 – aqueous urea solution 32.5%. A urea solution in demineralised water, its chemistry is defined in the international standard ISO 22241 which stipulates that it must contain 32.5 % (plus or minus 0.7%) urea by weight. With a specific density of 1.09, it is 9% heavier than water. Although classified as non-hazardous, it is corrosive to some metals such as aluminium alloys, copper, bronze and iron. Therefore tanks and containers for AdBlue must be made from a limited range of materials such as stainless or coated steels, high-density polyethylene (HDPE) or high-density polypropylene (HDPP). In North American markets, the same product is known as DEF (diesel exhaust fluid).

Handling AdBlue safely

According to the Environment Agency, AdBlue – if stored correctly - “poses minimal risk to operators and a limited risk to the environment.” Nevertheless, the Agency adds that AdBlue is “very polluting to surface water and groundwater” so there is no room for complacency where spills are concerned.

There are no specific regulations applying to the storage of AdBlue but the Environment Agency has issued a set of guidelines. It pays to follow these: if the Agency believes that failure to do so means there is a risk to a water source, it has powers under the Anti-Pollution Works Regulations 1999 to issue a works notice forcing the necessary improvements to be made.

oily jug

Using an oily jug to top up a vehicle’s AdBlue tank is one of the commonest sources of contamination for truck SCR systems.

The keys points of the guidelines are:

  • The storage tank and ancillaries such as the pump, hose and nozzle should have secondary containment – ie a bund.
  • The dispensing area’s drainage is isolated from surface water drainage.
  • The dispensing nozzle is trigger-operated with an auto shut-off: it must be incapable of being left in the open position.
  • You must have both an emergency spill kit and an emergency action plan, plus suitable training on how to deal with spills.
  • Because AdBlue is heavier than water (unlike diesel), underground interceptors or separators will not prevent AdBlue reaching surface water drains.


AdBlue dispensing

On-site AdBlue dispensing should be well away from surface water drains.

Storing and dispensing

On the basis that buying AdBlue from a pump at a fuel station or truck dealer will prove fairly expensive, it almost certainly makes long-term sense for truck operators to invest in their own on-site supply. Dispensing AdBlue alongside diesel on a depot’s fuel island makes replenishment swift and simple. 

Dispensing AdBlue

Dispensing AdBlue alongside diesel on a depot’s fuel island makes replenishment swift and simple

There is a wide variety of storage and dispensing options, starting with a 210 litre drum fitted with a hand-operated pump, ranging right up to a 15,000-litre bulk tank fitted with overflow and spill alarms, plus a telemetry system that places repeat orders when stock level reaches a pre-determined minimum. The volume of AdBlue consumed will determine which option is the most appropriate. An IBC holding 1,000 litres is a convenient method of storing and dispensing AdBlue for small fleets. The point where AdBlue consumption exceeds one IBC per month is reckoned to be where it justifies investment in a storage tank. A typical tractor unit will consume AdBlue at the rate of 4-8% of diesel consumption.

1,000-litre IBC

An IBC holds 1,000 litres and is a convenient method of storing and dispensing AdBlue for small fleets.

AdBlue must be kept clean und free from contamination, especially from oil-based products including diesel, which can lead to heavy repair bills. The liquid should be stored  within the recommended range of between minus 11 and plus 30 degrees Celsius. Although ice can form on the surface of the AdBlue, the delivery pipe takes it from near the bottom of a bulk tank, where it is unlikely to freeze, even in the harshest of UK winters. The cycle of freezing and thawing does not damage the solution.

Small container of AdBlue

Buying AdBlue in small containers at a service station is virtually a distress purchase, so expect to pay accordingly.

As most new diesel cars and vans now use SCR, AdBlue has become more widely available on garage forecourts. However, while the established 10-litre containers and the recently introduced 3.5-litre sachets are suitable for these light vehicles, buying AdBlue for a heavy truck in these containers is virtually a distress purchase, so expect to pay accordingly. As with most things, there is a direct correlation between quantity bought and price paid. At one extreme, we are aware of light vehicle dealer workshops charging £150 for a 15 litre top-up, while buying bulk loads by tanker can cost as little as 25p/litre.

Laser AdBlue funnel

For operators who fill from the smaller hand-held containers, Laser Tools has introduced a pair of AdBlue filling funnels specially designed to screw directly onto the AdBlue filler neck, in straight and angled versions. They contain an internal anti-spill valve which prevents over-filling and allows excess AdBlue to be returned to the container. The typical cost is around £28.50 for the straight version and £34 for the angled one (ex-VAT). More details from