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Stannous Chloride as a Drinking-Water Corrosion InhibitorLead and copper leaching into drinking water is a problem encountered in many areas of the country and is usually the result of corrosion inside the pipes. This corrosion releases the lead and copper by the oxidizing effect the water has on the pipe's surface. Drinking water has traditionally been treated with pH manipulation, silicates, and phosphates to inhibit corrosion within the infrastructure connecting the water source to the user. It has always been difficult to treat drinking water systems, since only chemicals approved for human consumption can be used. The older technologies have been rendered less effective; pH manipulation has limited effectiveness, requires gradual change (6 months or more) and is more likely to generate complaints about taste and smell. Silicates are largely ineffective and are rarely used. Phosphates are the most widely used corrosion inhibitor and have proven themselves to be very effective in most situations. The drawbacks to phosphates are the buildup of scale, which effectively reduces the pipe diameter, and the environmental consequences of adding nutrients to the drinking water system. Since 2000, AS Inc. has had a patented solution to these corrosion problems that is far more effective than pH control or silicates and without the damaging side effects of phosphates. AS-8150 is inorganic, environmentally safe and NSF/ANSI 60 certified for use to one part per million as product. FDA approval has been granted for quantities up to 1500 PPM as a food additive (compared to the 0.175 PPM typical drinking water application). AS-8150** does not add nutrients to the distribution system, which eliminates bacterial re-growth and the need for costly treatment before the wastewater can be discharged back into the environment. This site contains the theory behind stannous chloride's success as a corrosion inhibitor, tests and practical applications of AS-8150, and results of various water districts in using stannous chloride to reduce the amount of lead in drinking water. AS-8150 relies on the stannous ion to form an insoluble barrier to keep lead or copper from leaching into standing drinking water. The stannous ion deposits in waters of widely varying hardness levels, unlike phosphates which require reacting with calcium or magnesium to form an insoluble precipitant, .
** AS Inc. previously offered AS-8111 as a 50% solution for larger systems (> 2 MGD), where this concentration made sense. For smaller systems, AS-8111 was offered as a 5% solution. To reduce any confusion, AS Inc. is now offering AS-8150 and AS-8105.
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