The 'new brand' is called Mourne Water but there's a catch - it's tap water.
NI Water asked people from all over Northern Ireland to sample the 'new brand' and some were stunned to learn the water they were drinking was good old tap water.
Some members of the public said 'Mourne Water' was better tasting than both tap and bottled water.
NI Water filmed the reaction of people when they found out the 'new brand' was tap water and posted it on Facebook.
"Tap water undercover! Check-out these reactions. We sent tap water undercover – what will NI locals think of this fancy ‘new’ brand? Take a look…," wrote NI Water on Facebook.