More than two billion people, including children, don't have access to safe drinking water.
That's according to a new report from the United Nations Children's Fund (Unicef) and the World Health Organisation (WHO).
While the report says progress has been made to help poorer communities, there are still problems when it comes to the quality of water and the toilets that families have access to.
"If the water isn't clean, isn't safe to drink or is far away, and if toilet access is unsafe or limited, then we're not delivering for the world's children," said Unicef's Kelly Ann Naylor.
The research shows that 1.8 billion people have been given access to basic drinking water since 2000, but for many, availability and quality of water is limited.
It is estimated that one in 10 people (785 million) still lack basic services, including the 144 million who still drink dirty surface water.
Over four billion people are also living where there aren't safe toilets or properly managed sewage. While another three billion are not able to wash their hands properly with soap.
By using unhygienic toilets and not having things like soap, children and adults are at risk of picking up and spreading lots of diseases.
"Children and their families in poor and rural communities are most at risk of being left behind", Naylor said as she asked governments to "invest in their communities".