I bet this is a trick question!
On the off chance the question is not posed as a riddle, the dream could be about some sort of insult directed at the dreamer. Dirty water is not fit to drink - it is literally sickening. Envelopes represent messages, communications from some distance, or notifications. Together, dirty water and envelopes add up to disgusting communications.
It could mean a number of things. Maybe you heard about sharks and dirty water recently. We regularly incorporate current events into our dreams. If it is a symbolic dream, you'd have to figure out what the components of the dream mean to you. For instance, many people use "sharks" as a derogatory term for attorneys. So many people think that attorneys are "dirty," or they think of financial matters as "dirty." So it is possible that the dream is about legal or financial trouble, or a fear of such. Or maybe sharks represent a more general fear for you. The water being "dirty" would mean that the water is shallow, and outside of a shark's normal habitat and closer to humans. So you may be afraid that life is closing in on you, that there is trouble out stalking you. You might not be in the water, but the sharks are trying to get out.
I'm trying to cross the water dirty and I feel like drowning
It means that the mud indicates dirty things. You dream yourself with mud. This means that you imagine yourself with dirty things.
Dreams communicate in symbols. Dirty water might represent any number of things: pollution, bad thoughts, inability to get one's needs met, or a bad project at work. It could also mean that the dreamer needs to wake up to use the toilet.
it means your swimming in a pool with dirty water and fish.....get out!
Envelopes in a dream signifies anticipation or opportunity. Unopened envelopes indicates sad news or missed opportunities. The color blue represents truth, wisdom, heaven, eternity, tranquility, openness, loyalty, and devotion. It might be a desire to get away. This color in your dream may be a symbol of your spiritual guide and your optimism of the future. However, depending on the context of your dream, blue might be a metaphor for feeling sad.
Persons seen in dreams often represent the dreamer's self, particularly when the dream's focus is negative. This dream suggests that the dreamer feels "dirty" in the sense of being shamed or feeling guilty. Other details of the dream might provide more clues as to the dream's meaning.
Maybe that your judgment is impaired or your thinking is cloudy...something you once saw clear is not so clear to you anymore When You Dream Dirty Water It Means There Will Be A Lot Of Problems And Tears.
It means that you are trying to make a decision and the answer is not clear to you. There is nothing particularly bad or "dirty" about any of the possibilities, but there are so many options (lots of different fish) that it is difficult to decide what to do.
The suitcases in this dream probably represent a choice confronting the dreamer. "Clean" or "dirty" suggest that the choice has a moral element to it, with one option involving some sort of dishonesty or possible corruption.
it means you are having to do all the dirty work in life
Water bugs walk on water. So this dream might reflect longing to do the impossible or to rise above common problems.