1. Pathogens: These are disease-causing microorganisms like bacteria, viruses, and parasites. They can come from sewage, animal waste, and even human waste.

2. Chemicals: Dirty water can contain harmful chemicals like pesticides, fertilizers, industrial waste, and heavy metals. These can be released into the environment through agricultural runoff, industrial discharges, and even leaky underground storage tanks.

3. Solid Particles: This includes things like dirt, sand, debris, and even microplastics. These can make the water cloudy, taste bad, and clog pipes.

It's important to note that this is just a small sample of what dirty water can contain. The specific contaminants present will vary depending on the source of the water and the surrounding environment.