Yes it is possible to refill a tank of AdBlue yourself.

No! Even though AdBlue is made up mostly of deionised water, you cannot use water as a replacement. All AdBlue products meet specific standards, so it is essential that you do not use any other products as they could damage your vehicles SCR (Selective Catalytic Reduction) system resulting in expensive repairs and warranty violations.

AdBlue is essentially a solution of water and urea (a substance found in urine). However, in AdBlue, the urea is exceptionally pure and is of a high grade. The water used is deionised, so is vastly cleaner than water you would get from a tap. AdBlue is a non-toxic liquid that is also colourless in appearance, not blue as most people assume.

Selective Catalytic Reduction (SCR) is a technique used to clean up diesel emissions. Exhaust gases can be treated with AdBlue to remove harmful pollutants, including nitrogen oxides (NOx), of which nitrogen dioxide (NO2) is the most harmful.

AdBlue is a colourless liquid made up of high purity urea and deionised water, and vehicles with SCR technology will have a separate tank filled with it.

Unlike diesel or petrol it is not injected into the engine,instead it is released into part of the vehicle’s exhaust. When heated in the exhaust, it decomposes into ammonia and CO₂. The NOx from the engine exhaust reacts inside the catalyst with the ammonia and the harmful NOx molecules in the exhaust are converted to harmless nitrogen. In fact, AdBlue® can reduce your NOx emissions by up to 90%!

AdBlue is a registered trademark owned by the German Association of the Automobile Industry (VDA), which ensures standards are maintained.