Bring water and rice to a boil in a saucepan. Reduce heat to medium-low, cover, and simmer until rice is tender and liquid has been absorbed, 20 to 25 minutes. Spread on a large plate and let cool, about 30 minutes.
Combine cooled rice, chickpeas, tuna, peas, orange bell pepper, red bell pepper, green bell pepper, tomato, parsley, and garlic in a large bowl. Pour in vinaigrette dressing; toss well to mix. Cover and chill until serving.