I bought AO Smith water heater Jan 2018.After few months of usage, foul smell came whenever we use the water from the AO tank. Technician visited and cleaned the tank however within few days the same problem arised. I have registered a complaint before 10 days but still waiting for the technician. Technician called and advised we need to change the membrane which comes to 700 RS. I told them the product is still under warranty after that no response from them.