Maybe a little more practice with the Navy shower. Wet down with a trickle of water while soaping up. Rinse with a low flow. I also time the water heater. It varies a bit with temperature, but generally I need to heat water for 20 minutes and then it will be at the correct temperature so I do not need to waste more water adjusting the temperature. It should not take a third of a tank for two showers. One gallon per shower! You can also learn to economize with dishwashing. I use a dishpan with some warm soapy water and then a quick rinse. Dishwashing takes less than a gallon a day. I have a cassette toilet so it does not use water from the main tank.