As long as it doesn't have anything else in it but potassium Iodide and Iodine it is safe to take with water. The reason you can't go down to the drug store and buy Iodine to take internally is because they poison it with things like ammonia and non beverage isopropyl alcohol.
Even if you take too much Lugools it won't harm you. Some people take grams of it per day. 50 mg is 20 drops of 2% Lugols.