Bring the water for cooking sago to a boil, then put the sago in and cook for about 15 minutes. Be careful to stir while cooking to prevent the sago from sticking together. After 15 minutes of cooking turn the heat off, no need to open the lid of the pot, cover and simmer for about 20 minutes, when the sago becomes transparent you can get out of the pot.
The exact amount needed depends on the amount of sago.