I’ve always heard that people tend to use too much detergent.
According to this 2010 New York Times article today’s machines are much more efficient than they were 20 years ago. They use less water thus need less detergent. Additionally, detergents are much more concentrated.
Here is the test they suggest:
“Take four to six clean bath towels, put them in your front-loading washing machine (one towel for a top loader).
Don’t add any detergent or fabric softener. Switch to the hot water setting and medium wash and run it for about five minutes.
Check for soap suds. If you don’t see any suds right away, turn off the machine and see if there is any soapy residue.
If you see suds or residue, it is soap coming out of your clothes from the last wash.”
Try it. You may be able to cut your usage (and detergent budget) in half.