Many African countries are very poor and very dry, so they get massive droughts.
Often children have to walk miles every morning to get water.
Drinking water isn't always clean. This can lead to people getting diarrhoea and nasty infections from drinking it.
Mozambique was hit by a big drought in 2002, leaving millions of people without water.
Only half of the people there have access to safe water, and three quarters of children have had diarrhoea and diseases from the bad water.
In Tanzania, children spend an average of two hours a day collecting water, although in really remote parts it can take up to seven hours a day.