Question: I boil rice often and then store them. Next day when I take them out of the fridge, they are lumped together in one structure. I can heat them and then press them to separate them.

The same even happens within the pan in which I have cooked the rice, if I leave it alone for some 10s of minutes once the rice is ready.

What do I do to keep the rice separate?

Answer: 
To get very separate rice I use a long grain rice, pre-rinsed and cooked at a 2 to 1 ratio of water to rice by volume.

There are three factors that affect the tendency for rice to stick together:

* Length of the grain. Long grain is the least likely to stick together. Medium and short grain are starchier and are more likely to stick together.
* Amount of hydration. If your water to rice ratio is too high, it will cause even long grain rice to cake together.
* Cold rinsing. Rinsing your uncooked rice in cold water helps to wash away the excess starch. My basmati rice recipe calls for a rinse followed by soaking the rice in cold water for 30 min to an hour to ensure very fluffy separate rice.
I simply put the rice in a jar of water and shake like heck to rinse well i then use the two to one method and add a tiny bit of salt but most importantly a tablespoon of olive oil and another important thing to do is stir often . Another way i have heard of that i thought was crazy until i seen it done a couple of times is to put a wet teatowel on top of the pot. I am to scared of doing it this way as i dont want to burn the teatowel i am not sure but i think this is a middle eastern method ? But my freind cooked it like this once when he made a dish for me and him once and i have never had better rice