What's called in English for this type of Chinese food? It's made of rice and water. Refer to the picture.
The "proper" term is the Chinese name, congee. It's a perfectly acceptable (if not widely known) borrowed food term, like sushi or spanokopita or falafel or borscht or soufflé or (the ironically named) chop suey.
Congee (n): (in Chinese cooking) broth or porridge made from rice.
"Rice porridge" would also be fine.