How much water does a single person waste?

There is no exact answer to this question. It is estimated that on an average a single person wastes somewhere between 0 to 45L of water every day. Here are some of the most common causes of water wastage.
With rising water crisis globally, saving of water is of prime importance.
Some common Water Saving Tips include:

• Keep faucets turned off while brushing your teeth, shaving, washing your hands, doing dishes and so on.
• Fix all leaky faucets and plumbing.
• Wash fruits and vegetables in a pan of water instead of running water from the tap.
• Don't let water run while washing dishes by hand

You can read a more detailed list on Water Saving Tips here.