1 In general, the total dissolved solids concentration is the sum of the cations (positively charged) and anions (negatively charged) ions in the water.  Parts per Million (ppm) is the weight-to-weight ratio of any ion to water.
If you refrigerate the rice, and you want to eat it cold, its perfectly fine. People eat cold rice salads all the time. Cold rice pudding is fine. Its just sitting around at room temperature that is the problem.
To soak your rice, pop one cup of rice into 1 Â½ cups water with 2 tablespoons of some type of acid (I use lemon juice as I always have a lemon in my kitchen, but you can also use yoghurt, kefir or vinegar). Soak the rice overnight, then drain and cook as you normally would. Soaking grains is common practice in many countries â perhaps that is why they donât have the same problems digesting it as we do. When it comes to storing cooked rice, store it in the fridge for two days â no more.