The 1914 Pattern set nominally used the same Mk VI enamelled water bottle as the 1908 Pattern set (a range of substitute bottles in a variety of patterns and materials were introduced at the start of the war) and the design chosen to hold the bottle was clearly heavily influenced by the 1908 set, but manufactured in leather and with all straps of 1” width:
The bottle was secured in the cradle by a leather strap that passed over the shoulder of the bottle and secured with a brass stud on the front of the carrier, a slot in the leather offering a simple but effective method of fastening but allowing easy access for a drink if required:
Like the other components of the set, a pair of brass tongued buckles were attached to the carrier to allow it to be attached to the brace ends of the equipment set:
The fitting instructions recommended that the bottle be carried on the right hip, making it easy to draw for the right-handed soldier and to balance out the bayonet on the left hip. Most period photographs show this instruction obeyed and the right hip is by far the most common position to find the carrier being worn.
Tales from the Supply Depot 
Most right handed people also tend to have the right hip higher than the left one when firing in the prone position and a canteen would tend to be more irritating than a long thin bayonet scabbard.
WWI ended up in mostly static trench warfare but that wasn’t foreseen when this was designed so probably not a consideration.
I might be the exception to the rule, I’m left handed but I shoot right handed due to my ‘master eye’ being my right one, I’d keep the canteen on the left and the bayonet further back on the belt. I used this configuration when wearing modern web gear and the bayonet made a perfect prop for my back when sitting on the ground 🙂