You can buy everything you need in any of Namibia’s major cities, but as you venture further afield, expect fewer and fewer amenities. Make sure you always have a backup meal or two and buy plenty of car snacks for long journeys.
It’s also always a good idea to carry extra drinking water, even if you’re sticking to fairly well-travelled routes. Water is extremely scarce in Namibia and many places rely on boreholes, which are not always safe or pleasant to drink. In very remote regions – specifically Damaraland and Kaokoland – it’s absolutely essential to carry extra water and you should have enough for an emergency situation of at least two weeks.
Many 4x4s and motorhomes come with extra jerry cans and/or internal water tanks and you should top these up at every opportunity. Even so, buy a few extra 5-litre bottles just in case. In Namibia’s hot conditions you’ll need to drink much more water than usual to stay hydrated.