Reuters: Londoners should boycott bottled water in favour of cheaper, better-tasting and more environmentally friendly tap water, Mayor Ken Livingstone said on Tuesday. Bottled water served with meals in London costs 500 times more than tap water and is 300 times more damaging to the environment, he claimed. Launching his "London on Tap" blitz on Tuesday, Livingstone said using fewer bottles would help climate change. Bottled water, he added, left a higher carbon …