(Bloomberg) -- Parts of Johannesburg are facing water shortages because of increased demand and after power outages last week curbed supplies by the main distributor, in the midst of a heat wave.

Reservoirs across South Africa’s economic hub are either too shallow for water to be pumped to towers, or at critically low levels, Johannesburg Water said in a statement on its Twitter account on Tuesday. Supplies from Rand Water, the region’s main distributor, have been reduced because of electricity blackouts, it said.

Two Johannesburg hospitals -- the Rahima Moosa and Helen Joseph facilities -- are using mobile tankers to obtain water, it said.

“Johannesburg Water requests customers reduce consumption, only using water for human and household needs, which will significantly assist” in the recovery of the affected systems, it said.

Temperatures in Johannesburg are forecast to rise to 35 degrees Celsius on Tuesday, and 38 degrees Celsius in the capital, Pretoria, according to the South African Weather Service.

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