Fill the bottom of the sink with a few inches of warm water. This will rinse your blade just as well as running water. And far less wastefully. Check faucets and pipes for leaks. Even the smallest drip from a worn washer can waste 20 or more gallons a day.
Larger leaks can waste hundreds.
Use your automatic washing machine only for full loads. If you wash dishes by hand, don't leave the water running for rinsing. If you have two sinks, fill one with soapy water and one with rinse water. If you have only one sink, gather washed dishes in a dish rack and rinse them with a spray device or a panful of hot water. Don't let the faucet run while you clean vegetables.