In a slow cooker, combine the chicken breasts, water, chili powder, cumin, paprika, garlic powder, and salt.
Cover and cook on low for 6-8 hours, or until the chicken is tender and shreds easily.
Remove the chicken from the slow cooker and shred it using two forks.
Heat a flour tortilla in a dry pan over medium heat until it's warm and pliable.
Place a spoonful of shredded chicken in the center of the tortilla.
Top the chicken with shredded cheese, lettuce, tomatoes, and any other desired toppings (such as black beans, sour cream, or salsa).
Fold the sides of the tortilla in towards the center, then roll the burrito up tightly.
Repeat this process with the remaining tortillas and filling ingredients.