I believe your source is "trust me bro". Tap water IS NOT acidic. When you boil tap water the chlorine evaporates. Chlorine added to tap water is safe for consumption. RO water in the other hand depends on the condition of your filter. If you lama tak service (some people takde masa nak arrange for service) there might be bacteria in the water. RO is not safe for children unless you BOIL it again.