My water heater has outlived its advertised effective life by 1 year. It is in a semi-finished basement area that I rarely enter. If it fails how my last water heater failed (slow drip through bottom valve), it will cause no damage. However if there is a more rapid flow of water when it fails, it could cause some water damage before I notice the failure, potentially costing me about $1,000 at a slow water faucet rate of flow or $2500 at a more catastrophic rate of flow. I have already done everything I can to minimize those numbers.
My question: I know very little about water heaters. Given that mine is 1 year past its advertised life, how likely is it to fail within the next year? Within the next two years? And when it fails, how likely is that failure to involve significant water flow out of the heater at a rate faster than a drip?
All of this is to help me make my decision about whether to pre-emptively replace the water heater, or try to milk every day of effective life out of my existing one before replacing.