Gauteng, Mpumalanga and the North West could face water restrictions, with dam levels currently critical, the Water and Sanitation Department said on Thursday.

Although water restrictions had so far been avoided, metros were looking at how they could be implemented successfully, spokesperson Sputnik Ratau said.

"Once the metros know how this can be done, we have to go back and decide from there," he said.

Households needed to cut water use by 15%, and the agricultural sector by 20%.

The Vaal Dam was at 34% capacity on August 19, compared to 66% at the same time last year, according to Rand Water.

Ratau said the Vaal Dam system was at critical levels. It is the main supplier to Gauteng, North West, Mpumalanga and the Free State. Mogale City, on the West Rand, was the biggest consumer.

Residents urged to use water sparingly

The combined level of Gauteng dams was currently at 84.3%, four percentage points less than at the same time in 2015.

Should the Vaal Dam drop below 30% capacity, the Sterkfontein Dam would be used for emergency water supply. Its levels were at 89.5% on August 19.

In Limpopo, the department pleaded with residents to use water sparingly. The Nandoni Dam (57% capacity), Glen Alpine (2.5%) and the Nsami Dam (8.6%), as recorded on August 16, all desperately needed rain.

The Magoebaskloof Dam was at 100.2%, but this was not enough, due to the low levels of the other dams.

In KwaZulu-Natal, the Umgeni system, whose five dams serve mainly eThekwini and Msunduzi, was at 47.8% and Hazelmere at 53.6% capacity.