There are two kinds of rice recommended for paella. They are Bomba and Sollana. Both are a roundish short grain rice. Sollana is often called Calasparra after the area it is produced.
Whilst Paella originates from the region of Valencia, the best rice is grown in the neighbouring province of Murcia and more specifically Calasparra.
Calasparra rice is very highly regarded amongst chef’s in Spain and around the world, yet Calasparra rice makes up on a very small proportion of all the rice grown in Spain.
Rice grown in Calasparra is unique, as the paddy fields in which the rice grows is irrigated by channels built in Spain centuries ago by the Moors and the Romans. The constant flow of cold mountain water in the paddy fields ensures a constant supply of fresh cold water.
Because the water is cold, unlike the paddy fields elsewhere in Spain where rice is cultivated in flat paddy fields by the sea, the rice matures much slower, resulting in a much harder grain rice which contains less moisture and as a results can absorb more moisture when cooking, making it ideal for Paella.
Any rice produced in the Calasparra region is regarded as the best for Paella, however Bomba is the superior rice. Bomba is able to absorb more liquid yet still keep its form, with the grains remaining separate when cooked.