In large bowl mix flour, sugar, yeast and salt. Gradually stir in the water; beat or whisk until smooth. Cover with towel; set in warm (80-80 degreeF) draft-free place- the kitchen or the other warm room in summer or in cold weather on top of insulated furnace or radiator, on a buffer such as a folded heavy towel or pillow.
Stir 2 or 3 times a day for about 3 days or until starter is bubbly and produces a yeasty aroma. Transfer to larger bowl, large jar or plastic container. Cover partially (tilt lid or punch holes in plastic cover); refrigerate.
