I have an electric Water heater and it is starting to leak from what I believe to be the pressure release valve. I just wanted some tips on how I can fix this before the leak becomes unmanageable. The water is a couple decades old and rusty, heck the hot water inlet valve is rusted stuck open.
I ran out of space composing an comment response to Rick's last comment, so I'm going to just make everything into an answer. First my original comment:
This heater appears to be much more than 20 years old! I agree a new installation is the best option. However, if money is tight, the valve alone should be replaceable for little money and will fix the leak, but not the other deficiencies. But with old plumbing, you are as likely to break something as to take it apart, so you may end up with a new heater anyway.
And my response to Rick's comment:
I doubt the water is very hot by the time it drips out, any hose should work, use a washing machine hose if you want one that is heat resistant in case the valve actually blows. You will need a male pipe thread to male hose thread adapter fitting to connect a hose to it. Alternately you could fabricate a drain out of CPVC pipe and fittings.
To replace the valve, take the old one out and take it to a hardware store and find a "Domestic Temperature and Pressure Relief Valve" of similar configuration. Ensure the pipe thread that goes into the heater is the same size and gender. Also insure the temperature probe is similar in length or at least is long enough to extend through the heater's internal insulation and protrudes into the tank proper. While you're there, get some pipe dope and enough CPVC pipe, glue and fittings to extend the outlet to near the floor. You don't want a family member sprayed with scalding hot water should the valve release when someone is nearby.
Honestly, you should avoid the sink/hose drain option and replace the valve, they are not that expensive. Just don't break anything removing it. If something feels like is about to break on disassembly, then maybe the hose/sink option makes sense. But for your own sake, please start saving money to replace the entire installation. It's not going to last a lot longer.
Your best option is a new heater.
There are also a number of other deficiencies..
The outlet from the pressure relief valve should be vented just above the floor. The water connections appear to be flex gas pipe. The mixture of metals, copper, galvanized steel is contributing to the corrosion.
Update Any money spent repairing this heater is a waste. How much will you spend repairing flood damage? Any mechanical stress (loosening/tightening connections ) may cause unintended consequences. This leak is your heaters LAST warning. Don't try to finesse this.