“The African National Congress is saddened by the news of the death of two more babies from a diarrhoea outbreak,” spokesman Zizi Kodwa said in a statement on Monday.
“We send our deepest sympathies to all families affected and wish them strength during this difficult time of loss.”
The North West health department earlier confirmed the death toll had risen to three.
“One baby was seven-months-old and the other was 13-months-old,” spokesman Tebogo Lekgethwane said.
They died under circumstances similar to those of the first baby, who died last Wednesday.
Dozens of residents went to local clinics for help last week following the water contamination. Five babies were admitted to hospital for observation on Friday.
The Lekwa-Teemane municipality shut off its water supply system more than a week ago. The national water affairs department said the system had been cleaned and sanitised, and water supply was restored on Thursday evening.
But residents said the water from the taps was still brown on Friday, and they had been asked to boil it before using it. Water samples were taken for testing.
The National Institute for Communicable Diseases said on Monday that tests for cholera were negative.
Water and Sanitation Minister Nomvula Mokonyane visited the area on Sunday. Her spokeswoman Nomvula Khalo told Sapa she expected to receive water test results on Monday afternoon.