The tank type we had in one of our travel trailers was I think either a 5 or seven gallon. Quick showers were the norm, very quick, but that size would be great for under the sink and they recover fast. Add a timer to it for morning and night along with a timer for the main tank and you save on energy.
They also make a circulation pump for the kitchen or where there is a long run from the tank that will bring hot water to the faucet without running the water and you can save water that way.
Our hard water here is killer on the heating elements and anode rods in the tanks. To drain my tank I have shut-offs installed on the inlet and outlet on top of the tank and an air fitting installed on the tank side. If I need to pull the elements I can maintain my 35lbs of pressure on the system so it can drain faster. I wish that the tanks had a big plug in the bottom so the scale could be cleaned out while servicing the tank.
They also make a circulation pump for the kitchen or where there is a long run from the tank that will bring hot water to the faucet without running the water and you can save water that way.
Our hard water here is killer on the heating elements and anode rods in the tanks. To drain my tank I have shut-offs installed on the inlet and outlet on top of the tank and an air fitting installed on the tank side. If I need to pull the elements I can maintain my 35lbs of pressure on the system so it can drain faster. I wish that the tanks had a big plug in the bottom so the scale could be cleaned out while servicing the tank.