No, you should not use water instead of AdBlue. AdBlue is a urea-based fluid that is specifically formulated for use in diesel engines with selective catalytic reduction (SCR) technology to reduce emissions of nitrogen oxides (NOx) in the exhaust gas.
Water does not have the same chemical properties as AdBlue and will not react in the same way with the exhaust gases to reduce NOx emissions. Using water instead of AdBlue can cause damage to the SCR system and the engine. It can also void the vehicle’s warranty and may lead to the vehicle failing emissions testing.
It’s important to always use the correct fluid and to follow the manufacturer’s recommendations for refilling and maintenance of the AdBlue system.