Centre Rachel Burford scored a try on her debut
Tries: Day (4), Crawford (2), Rae, Clark, Burford, Rudge, Yapp, Barras
Cons: Rae (7)
South Africa 8
England bounced back from a lacklustre opening match against the USA to thrash South Africa in the Women's Rugby World Cup in Canada.
Worcester's Nicky Crawford scored the first of England's 12 tries after four minutes with Shelley Rae converting.
Stand-in captain Sue Day added four tries while debutant Rachel Burford also touched down as the Boks struggled to deal with the England pack.
England go on to face a crucial tie with France on Friday at 0000 (BST).
Only New Zealand, Scotland, France and England remain unbeaten after two rounds with semi-final berths to be settled on Friday.
England coach Geoff Richards said: "It's great to get another win under our belts.
"The hot weather made it difficult but we stuck to our task and performed well.
"The team are always looking for the perfect game and they kept going until the final whistle which is great to see."
England and Henley centre Burford was also satisfied with her performance in Edmonton after she powered over the line on her debut.
"It was great to score a try on my debut," she said. "It was such an awesome feeling and I desperately want to be involved against France.
"To be honest I didn't want this game to finish."
World Cup results:
New Zealand 50-0 Samoa
France 24-10 Australia
Scotland 32-17 Kazakhstan
United States 24-11 Ireland
Canada 79-0 Spain
Sue Day (capt, Wasps); Nicola Crawford (Worcester), Michaela Staniford (Henley), Rachel Burford (Henley), Danielle Waterman (Henley); Shelley Rae (Wasps), Amy Turner (Wasps); Vanessa Huxford (Wasps), Selena Rudge (Wasps), Katy Storie (Clifton), Jenny Lyne (Richmond), Tamara Taylor (Thirsk), Shannon Baker (Richmond), Helen Clayton (Saracens), Georgia Stevens (Clifton).
Replacements: Amy Garnett (Saracens), Vanessa Gray (Wasps), Jennifer Sutton (Richmond), Margaret Alphonsi (Saracens), Jo Yapp (Worcester), Karen Andrew (Saracens), Charlotte Barras (Lichfield).