Unfortunately, there are many people throughout the world without a sufficient supply of fresh drinking water (you can learn more about "the water crisis" here). In some communities you would have to walk miles just to fetch dirty water from a river or well.
In India, children - usually girls - are forced to miss school because they need to stand in line waiting for water to arrive. Many schools also don't have clean water, and even more go without tap-water or any other water source.
There are many areas where water is very rare. Sometimes only wealthy people have access to water. There's even some places where water has been such a rare resource that there have been wars and battles over it. Kenyan tribes fought battles over water in February 2006 and in July 2005 thirty-eight people and twenty-two children were killed in the village of Turbi due to rivalries between tribes. In Yemen, the villages of Al-Marzuh and neighbouring Quradah fought in a dispute that involved over seven hundred soldiers, killing six people and injuring sixty, over a local spring.
However, there are things being done. Numerous charities make efforts to improve life and provide food and water throughout the world,
What can you do?
A large organization which frequently sends volunteers to African Villages started off as a high-school club. You are definitely not obliged to do something like that - but even small things such as conserving water at home (turning off taps, not wasting water, etc.) can help. If you want to do something bigger, make a plan and have a goal. Try to predict what you'll do and how you'll do it. You can read a great article on goal-setting here. For example, in the far future H2O hopes to be a charity site to provide clean tap water to schools.
Please visit the links page for a list of websites where you can find more information about water poverty and other subjects.