There is a lot of energy (called Energy Water Nexus) tied up in the water we get from our tap. What do I mean by that ?  Well in order to have water in our cities it needs to be imported from another part of our state. For Southern California it’s imported from the northern part along the aqueduct.

These are the numbers for Southern California but every city in the world has similar calculations.
The total energy percentages:
3% of all the energy consumed in California is use to transport water to our cities.
12% of all the energy consumed in California is used to clean the water,
2% is used at our home to heat it in our water heaters.
Another 3 percent to clean it once again and pump it out to the ocean, and dispose of the sludge.
Total: 20 percent of all the energy consumed in California is tied up with water.

How to cut this number:
1) reusing the shower water and laundry water (Greywater) for landscapes will cut 6% to 10%, since the amount we are using to transport and clean to use on landscapes goes away.
2) 3% goes away since we are not cleaning the waste water to dump into the ocean and dispose of the sludge.
3) Washing clothes in cold water, taking shorter and warm showers will cut the energy to heat the water dropping about another 2 percent.