The Sigma's water tank is locked and can be opened with the little key that's on the key chain. Look for the key with the word CAMEC on it - see photos below. As the Sigma is such a new vehicle and the water tank & its lock are brand new, the key may be a little stiff it its usage. But rest assured it's the right key so please use that key to open the water tank of the Sigma Campervan.
