On becoming more efficient...

Our water heater is supposed to be new but has been acting up recently which has led me to do some research into the concept of a tankless water heater. With four young women living here and the number of showers, washing hair, baths, etc., it's becoming increasingly difficult to still have hot water. Which in reality means it is probably not a problem with our hot water heater but one of supply and demand. It does appear from an efficiency standpoint that it could be more cost effective for a tankless system.