Water leaking water heater

Problem with Rheem 40 GAL ELEC TALL Water Heater 6YR SC 82VH402


Water leaking observed from the bottom of the tank. What's the problem? Should I replace the old 21V40-2 unit? if so, what kind of tank is ok to replace the present unit? What's the price and installation fee? 


If water heater is leaking, then open following 2 links to avoid tank rupture and troubleshoot leak:
http://waterheatertimer.org/Emergency-steps-for-leaking-water-heater.html
http://waterheatertimer.org/Water-heater-is-leaking.html

Open following link if you want to install your own gas water heater:
http://waterheatertimer.org/How-to-install-gas-water-heater.html

To have gas water heater installed, can run $2-300 for installation plus cost of heater.
40 gallon natural gas water heater at Lowes starts at $300+, and tanks with longer warranty cost more and last longer.

If you maintain the tank: keep chemicals out of same room as water heater, attach bare copper ground wire between hot and cold pipes, flush tank each 6 months, clean burner each year as shown in manual, read the manual entirely for specific information about your model, and inspect/replace anode rod every 2-3 years then basic 6-year tank can last much longer.
http://waterheatertimer.org/Replace-anode-rod.html
http://waterheatertimer.org/9-ways-to-save-with-water-heater.html