In a large pot, bring the 4cups of water and coconut milk to boil.
Add 1/4 cup of sugar and simmer.
Then add sweet potatoes and plantains and simmer until half done.
Add 3 tbs water to the sweet rice powder a little bit at a time until it becomes a big dough ball. Take a little of the mixture at a time and form into balls the size of hazelnuts. Drop the balls into the simmering mix.
Add the cooked tapioca, sugar and langka. Stir and cook for 5 minutes.