Manufacturer's of dishwasher detergents have reduced the phosphate content in their products to less than 0.5% in order to comply with new regulations that were adopted by sixteen states including Massachusetts. The new regulations went into effect on July 1, 2010. Some detergents contained as much as 8.7% phosphate so there could be a substaintial reduction depending on the brand of detergent you use. Phosphate is typically the limiting nutirient in fresh water enviroments. The reduction is intended to curb problems caused by excessive phosphate loading such as low dissolved oxygen content and algeal blooms in fresh water bodies.
One of the main benefits of using phosphates in detergents is that it prevents mineral deposits from forming on dishes as they dry. The calcium and magnesium content of water is commonly referred too as the hardness of the water. Phosphates were added to detergents to counteract hard water. Most groundwater sources New England, including our two water sources, contain high amounts of calcium and magnesium and are considered hard. The minerals are dissolved from soil and rock formations as the water flows through the ground. Water withdrawn from surface water supplies such as streams, rivers and lakes typically have much lower mineral content and are considered soft.
Some customers may notice a whitish deposit on items washed in the dishwasher as a result of the change in the formulation of the detergents. Similar deposits form on cars if left to dry in the sun after being washed. A white ring is left where water droplets used to be. The deposit is the mineral content left behind by the water as it evaporates.
Reports in the press indicate that detergent manufactures are still adjusting the content of their products to correct for the loss of phosphates. Different detergents, including ones from the same manufacturer, will yield different results depending on how the detergent reacts with our water. Possible solutions include trying a new detergent until one is found that works well, trying rinse agents to prevent formation of deposits, hand washing the dishes and using the diswasher without detergents to periodically sanitize the dishes, or installing a water softner. Water softners remove the calcium and magnesium ions by swapping in sodium ions.
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