(57) An automatic dishwashing detergent primarily comprised of an alkali-metal carbonate as the sole builder, alkali-metal silicates, and a calcium precipitation inhibitor system consisting of a low foaming surfactant, a low molecular weight polycarboxylic acid, and a small amount of a threshold inhibition agent. Optionally halogen, peroxygen or peracid bleaching species enzymes, fragrances, dyes and other adjuncts may be included. The composition provides good cleaning performance especially on starchy soils, and no appreciable calcium precipitates results, even in water having a hardness of at least about 400 ppm.