Oh dear I hope this doesn't give you a bad impression of Dubai!
I've just rented a water system from Oasis - Dhs 300.00 for the year for the water cooler (it pumps out REALLY cold water) and the 5 gallon bottles cost Dhs 7.50 each. Bargain! And they deliver it all free. And it's more environmentally friendly than buying hundreds of litre plastic bottles