It's time to have a house meeting and request that the house set down some mutually agreed upon ground rules. Share your feelings about the current situation. Don't make it personal. For example, "When there are dirty dishes left in the sink for more than a day, I feel sad/angry and like I am living in squalor."
Since your name is not on the lease, the only leverage you have is to pose the reality that if there are no ground rules that you may consider moving out. And, you have to be prepared to make that choice if the other roommates choose not to have ground rules. A stable home environment is critical to personal happiness.
Try to start the conversation from points of agreement.
Does everybody like to live in peace, or in a party zone?
Does everybody like to live in sanitary conditions, or in squalor?
Depending upon the answers, you may have to make the tough decision to move out. Or, there may be hope that the situation can be salvaged.
From some basic questions (look to Maslow's hierarchy for some guidance), you can then ask specific questions about what might be some ground rules that everybody agrees to follow so that peace and other agreed upon aspects of the living condition are maintained.
When you get agreement. WRITE THE GROUND RULES DOWN. Then, EVERYBODY SIGNS the ground rules and they get posted in a conspicuous place, like the refrigerator. Make extra copies just in case the original "gets lost".
When somebody violates a ground rule, it is the responsibility of everybody to "call it out". It is the responsibility of the offending party to "make right" AND possibly do something extra.
In this way, the group establishes the "cultural norms" by which the group agrees to abide. It makes it easy for everybody to understand what is the minimum expected.
There is a myth regarding communication. And, that myth is that it has happened.
Make communication happen and document the results with mutual agreement.