Bottled Water. A multi million (billion?) pound industry where businesses put water in bottles, market it heavily and make big fat profits.
And all you need to do is turn on the tap and out it comes. You already pay your water rates/have a water meter, so why on earth are you paying someone else to make big profits on something you're already paying for?
And then there's the whole industry of making the plastic bottles to fill up and throw on the streets or in the trash - What a waste of resources, just take a reusable bottle out with you, fill it up at home.