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. If possible, however, try to find rain water, which is collected in metal or plastic tanks and usually 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. Services Bylong water tank, friendly general store with liquor, free camp site at tennis court. Free camp by railway line on S side Clarence Town pub, general store, van park.