The proportion of the world’s population with access to improved drinking water sources grew by 10 percent over a period roughly covering the past two decades, according to a United Nations study released Tuesday.

The study was released by the United Nations Children’s Fund (UNICEF) and UN World Health Organization (WHO).

The study found that between 1990 and 2008, the proportion of the world’s population with access to improved drinking water sources increased from 77 per cent to 87 percent.

However, impoverished regions in sub-Saharan Africa, Southern Asia, Eastern Asia and South-East Asia are falling behind the progress.

“The good news is that almost 1.8 billion more people now have access to drinking water compared to the start of the 1990s,” said Sanjay Wijesekera, UNICEF’s associate director and water and sanitation chief. “The bad news is that the poorest and most marginalized are being left behind.”

For example, the actual number of people without access was greater in 2008 than it was in 1990 in sub-Saharan Africa. The richest 20 percent in sub-Saharan African countries are more than twice as likely to use an improved drinking water source as the poorest 20 percent, according to the report.

More than eight in 10 people without improved drinking water sources live in rural areas where the greatest burden in collecting water falls on women and girls. The proportion of the rural population in developing regions using piped drinking water on premises was still only 31 per cent in 2008, up from 21 per cent in 1990.

One organization seeking to boost water accessibility says project sustainability is key.

“While drilling a well can be easy, delivering water and sanitation solutions that are sustainable in the long haul is not and involves a number of important components,” states the website of Water.org, a non profit venture co-founded by Matt Damon and Gary White. The group operates in communities in Africa, South Asia, and Central America.

The group works with indigenous partner organizations to understand the culture, create local water committees, provide necessary technology specific to each community, and educate on good hygiene practices.

The group requires local partner groups to “submit program and financial progress reports on a quarterly basis, and to evaluate their projects after the first year of completion to measure what outcomes have emerged from the project and what lessons they have learned to guide future efforts.”

The internationally-agreed poverty and social development vision known as Millennium Development Goals (MDGs) set a goal of cutting the proportion of people without sustainable access to safe drinking water and basic sanitation in half by 2015. At the current rate, 672 million people will still not be using improved drinking water sources by the deadline.