I want to use a juicer to squeeze watermelon water without using water or sugar
No, but if you want dessert, you can add some sugar
You buy a watermelon sweet from water is sweet; buy watermelon is not sweet from water is not sweet, then add sugar or honey is ok. Have a good appetite!
Water must not be added, because watermelon is a lot of water. Sugar?! It depends on your taste
