When cooking rice in a pressure cooker, the general rule of thumb is to use a ratio of 1:2 for rice to water. This means that for every cup of rice, you would typically use 2 cups of water. While making chicken biryani in a pressure cooker the chicken and other ingredients (like yogurt) release some moisture during the cooking process. Also, when we soak rice in water, it absorbs some water. You may need slightly less water to cook biryani.