How long does it take water to get hot in a hot water heater Doing a lot of clothes washing in hot water and want to know how long it takes the hot water heater to heat back up after its gone cold?

depends on the gal size and btu of the heater. look on the panel and it will tell you the gals and btu. also is it gas or electric, single element or double. most 40 to 50 gal heaters will recover in about 25 to 45 mins.I AM A MASTER PLUMBER LOCATED IN Texas. Hope this helps.