Delays to the second phase of the $2 billion Lesotho Highlands Water Project have left Gauteng — and a wider region that accounts for about 60% of South Africa’s economic activity and in which 26 million people live — without adequate supply, said Sean Phillips, director general of the Department of Water and Sanitation.

Until the Lesotho expansion is completed “supply is very tight,” Phillips said on a Webinar on Wednesday organized by Creamer Media.

The threat of inadequate supply to the country’s industrial heartland was highlighted this month when a vast swath of the country’s biggest city, Johannesburg, was left without water for almost two weeks after a breakdown. Rand Water, the bulk supplier that draws water from the first phase of the Lesotho Project warned Johannesburg and two other major urban centers that its systems were on the verge of collapse.

The Lesotho project consists of the construction of the Polihali Dam in Lesotho as well as tunnels to transfer the water to the Vaal River system in South Africa. It will boost annual supply of water to South Africa from Lesotho to 1.26 billion cubic meters (44.5 billion cubic feet) from 780 million currently.