Stains teeth

I really dislike plain water. I drink a lot more fluid by using this water flavoring all the time. I really like this product but it stains my teeth badly. The only clear one I buy now is coconut pineapple. Yummy. But my teeth are still getting stained.
What is in the product to cause this

Also sadly when i drink this first thing in the morning it irritates back of my throat problem due to acid reflux Makes me cough
This is the only good tasting very low calorie drink I can find so i dont use anything else

I dont want to give it up but having to constantly try to remove the stain is so counter productive
Any suggestions

I love adding one squirt of this to 2 cups of water. It makes the water tastes so refreshing and helps me drink more water throughout the day. I like the fact that you don't need a lot of this to make your water taste delicious and flavorful. If I add more than one squirt per two cups of water, I personally find the flavor to be too strong, which is great since it allows me to maximize the number of coconut pineapple drinks I can make. I found mine at Wal Mart.