I don't personally soak basmati rice before cooking it, but some recipes include soaking the rice in water for up to 30 minutes. There are several reasons that some cooks like to soak basmati rice. 1. This can serve the same purpose as rinsing the rice, which removes starch and prevents the rice from clumping or getting sticky. 2. Soaking helps grains of rice re-hydrate and plump up. 3. Some also believe that soaking rice helps remove toxic substances, like trace arsenic.