Well, I took the T off of the outlet, checked it out carefully and did not see any defects (didn't expect any after 4-years, but who knows), put it all back together and the leak was the same or maybe worse since I'd knocked off all of the accumulated mineral deposits. So, I called the plumbers. One guy came, looked at it carefully and said he was pretty sure it was the tank, he called his office, and later that morning, they came and replaced the tank. The design has changed a little bit meaning it might have been because they had problems (or maybe, this way is just cheaper to manufacture). Anyway, it necessitated some slight plumbing modifications, but since they didn't have to add valves and rearrange pipes like they did on the last replacement, this time, it 'only' cost me a bit over $200, mostly labor. So, the lifetime warranty, since installation, has cost me over $500 in replacement costs...I'm not thrilled, but hope this time, this one lasts a very long time. Hope your results are better.