Rule of thumb when it comes to soft drinks is anything with NO citric acid...
and, so it would seem, NO lactic acid
Tea
Coffee
Coke Zero
Asda Diet Coke
Dr Pepper Zero
Bouillon
Green Tea
Peppermint Tea
tescos own strawberry water
Sainsburys strawberry and kiwi sparkling water
Asda Cola Zero (No Citric Acid and even better no aspartame)
Sainsbury's Flavoured Still Water (Raspberry & Cranberry, Peach, Apple & Blackberry)
Sainsbury's Diet Cola (No Citric Acid or Aspartame)
Sainsbury's Classic Diet Cola (No Citric Acid or Aspartame)
Sainsbury's Classic Zero (No Citric Acid or Aspartame)
Asda diet cherry cola
Co-operative diet cola