Taking a shower is popular, but many people still like to take baths. Baths are nice and relaxing I suppose, but they use much more water than a shower. Unless you must take a bath to get clean, a shower is a better way to save water. One bath uses as much water as two or three long showers. Short showers save even more.
Brushing your teeth is another place where we can save water. If you're a typical American, you enjoy watching the water run down the drain in the sink while you brush your teeth. It's as entertaining as it is wasteful.
Washing the dishes and cleaning up the kitchen can be a big contributor to wasting water. So many people just can't clean off the table, load the dishwasher, wipe down the counter or clean dishes without having the water constantly running down the drain in the sink. Perhaps it's like background music that soothes the savage kitchen cleaner.
If you wash your car with any regularity, then it represents an opportunity to save water. I don't wash my car very often because the dirt roads out here make regular car washing pretty much a wasted effort. But others have such a need to be more presentable.
Tree watering is just like any other use of water, it can be wasteful or efficient. Use drip systems, "catch baskets" and mulch to help save water and still grow a nice bunch of trees for your enjoyment.
Cleaning the driveway can be a complete waste of water. When I was much younger, my neighbor used to chase elm seeds down his driveway with a hose. He clearly wasn't "signed up" with the save water and save money crowd. His driveway was the cleanest in the neighborhood, for an hour or so, and then the elm seeds fell on it once again.
Lawn watering uses hundreds of gallons of water. If you must water your lawn, the best advice to save water is to make certain that your sprinklers are watering the lawn and not the sidewalk or street. Also, runoff is a big issue to deal with.
Leaky faucets don't usually present a sense of urgency, but they do waste water - 24 hours a day.
Flushing the Toilet is something we do every day, and it uses gallons of water at a time. This water consumer can be tamed by a "best practice" or technology.
Grey water systems are also a way to save water. They capture water from relatively sanitary sources in your home and use it to water trees and lawn. Just about any source except the toilet is acceptable, but there are some issues with filtering out lint, hair and other solids, and of course, government regulations.
Make an effort to save water as part of your approach to frugal living. Water is essential to life, so we should use it wisely.