In large microwavable bowl, mix cereals, crackers, pretzels and peanuts.
In small bowl, stir together oil, water and taco seasoning mix. Pour over cereal mixture, stirring until evenly coated.
Microwave uncovered on High about 5 minutes, stirring every 2 minutes, until mixture begins to brown. Spread on waxed paper or foil to cool. Store in airtight container.