Consider installing an instant water heater on your kitchen sink so you don't have to let the water run while it heats up. Defrost frozen food in the refrigerator or in the microwave instead of running water over it. Use phosphate-free detergents. Choose natural cleansers - borax, ammonia, vinegar, or baking soda. Recycle water from your fish tank by using it to water plants.
Fish emulsion is a good, inexpensive fertilizer high in nitrogen and phosphorus.
Outside Do not drink water directly from a pond, creek, stream, river, or lake without bringing it to a rolling boil for at least one minute. Let the water cool before drinking it. Use a broom rather than a hose to clean sidewalks and driveways. Place a layer of mulch around trees and plants to retain water. Use a moisture indicator to tell when your lawn needs watering and when it does not.