The Mt Victoria pass is very steep for about 3 km on the W side, without a shoulder - you will need good brakes and some nerve. In all cases, it will be worthwhile to wear brightly coloured clothing to enable motorists and truck drivers to see you as early as possible - in particular, avoid dark helmets. Water The longest stretches without access to drinking water would be around 20 km or less. Tap water is theoretically safe to drink in all places, though there is concern with septic run-off contamination in the Mountains following rain. If possible, however, try to find rain water, which is collected from roofs of buildings into metal or plastic tanks and is usually much more palatable - farmsteads will usually be happy to provide drinking water.
Bottled water is readily available in large supermarkets.
Ground water will not be safe anywhere. Supermarkets often have liquor stores attached. Be sure to bury all toilet waste carefully. In many places there is enough wood for a small pit fire, and you can cook or make damper easily. Use wood sparingly and observe all fire precautions and bans - always bury your fire when you leave.