Any thoughts on what the problem is? It is leaking about a 2 cups or so a day. Do I have to replace the water heater which is now over 15 years old? is your water extremely hot ? if so your thermostats are not shutting off causing temp to go above preset level of relief valve (150) replace therms.

You may have a lot of mineral deposits causing the valve to stick partly open. You should change the valve and completely flush out the tank. I wouldn