We replaced an old water heater with a new AO Smith gas water heater. About 2 weeks later the screens on our faucets were filled with green and white grit which caused low water pressure. We have 2 water heaters. The non-Smith heater does not produce grit. AO Smith had us hire a plumber to come out to tell us what to do. He said that the water heater was producing grit. AO Smith customer service says that we have to pay to replace a part because the grit is caused by our water reacting to their heater part. We have city water which has never produced this problem in any of our other water heaters. Based on the current AO Smith lack of customer service we will probably have to replace the heater at our expense. Believe me it will NOT be with an AO Smith heater.