If made properly over 1,000 years
That depends on how much water is drawn from the tank and how often it is drawn.
how long does it take for hot water after lighting water tank its gas?
Your hot water tank is not working properly or someone used up all the water before you did. If one element is blown on an Electric tank and the other is working, your hot water will not last very long.
They can be made out of plastic for easy use, movement and disposal but they wont last as long as other materials. They can be made of various metals that can last a long time.
The hot water tank might be undersized for your usage.
About 120psi for a 16 oz propane tank
20 years at least, provided the hot water heater is serviced and maintained by a plumber once a year.
how long does a water spout last
A 20 pound propane tank holds 4.1 gallons of LP which equates to about 0.016 cubic meters. If your heater burns 3 m3 per hour the tank will last about 19 seconds. If you meant .0003 then it will last 51.73 hours.
Bladder water tanks are relatively durable, however they will not last as long as steel and other metal water tanks. They are very favorable, however, for when you need your water tank to be mobile, as they are easy to transport.
If you just filled the tank on a 40 gal. about 30 to 45 min.
You can not answer that question without knowing more about the size of the hot water heater, the size of the stove and oven combo. How often the stove/oven is used, and how much hot water is heated. Water temp. is a factor as well.