The country’s commercial capital, Lagos, faces a water crisis that is creating unacceptable conditions for millions of people, a United Nations expert said on Thursday, but a state government official says spending is being increased to alleviate the problem.

The 21 million residents of Lagos, which is built on a lagoon, struggle to find water suitable for drinking and sanitation. Estimates suggest only one in 10 people have access to water supplied by the Lagos Water Corporation, the state utility provider, according to the UN.

Reuters reports that this has been compounded by years of mismanagement, said Léo Heller, the UN special rapporteur on the human rights to water and sanitation, after the Lagos State Governor, Akinwumi Ambode, presented a proposed budget for 2017 to the state House of Assembly.

“Government reports indicate alarmingly high deficits in the sector, representing clearly unacceptable conditions for millions of the megacity’s residents,” a UN statement quoted Heller as saying.

More funding could be used to improve the state utility provider, adopt financing schemes and reduce water losses, he said.

Reacting to the comments, the Commissioner for Information and Strategy, Steve Ayorinde, said the 2017 budget increased spending with the aim of addressing the two key issues of potable water provision and cleaner environment.

But he said the migration of people from other parts of Nigeria and neighbouring countries had put pressure on the city’s infrastructure.

“Private capital is required in the state government’s quest to provide more access to potable water,” he said, adding that the Lagos State Government was “determined to explore” public-private partnerships.

Lagos is the biggest city in Africa’s most populous nation.

Despite having Africa’s largest economy, Nigeria has one of the highest child death rates from water-borne diseases in Africa. It has sought international development help to finance new water treatment plants and expand its distribution networks.

As a result of the creaky public water system, many residents rely on private water suppliers, or bore into pipes themselves. Damaged pipes leak millions of gallons of treated water, about one-quarter of the supplies meant for homes, schools, hospitals and industry.