Fresh water tank drain; Keystone Premier Bullet 19FBPR

I don't have your specific model, but I do have a Keystone Bullet Premier, and what you are describing sounds like my drains. I have a single blue line in the front (the fresh water drain) and 2 lines further back (low point drains, and I don't remember the color). Mine have a white cap on the end that you unscrew, and the water falls out on you. It takes a little more effort to get the water from the low point drains (I usually have to open a faucet somewhere to allow the air in).