Plan every litre from fill point to drain

Plan water from the daily routine outward: drinking, cooking, washing, showers and cleaning all draw from the same finite supply. Record how many people travel and how often you can refill and empty waste. A large fresh-water tank can extend a stay, but it also uses space and payload. Compare the loaded condition, including people and equipment, before choosing tank capacity from a photograph of another build.

Draw the complete path from fill point to tank, pump, filters and outlets, then the waste path and drain points. Identify what needs access for cleaning, winter draining and repair. Keep drinking-water materials and fittings appropriate for their use, and follow their manufacturer instructions. A neat hidden installation is less useful if the strainer cannot be reached or a small leak is trapped behind a finished wall.

Match pressure and flow across the whole system. The pump label alone does not establish that every tap, hose, heater and fitting can accept the same conditions. Consider vibration, noise and how pipes move as the van travels. Record the mounting method and the safe isolation procedure for servicing. Hot water adds another set of energy, scalding and pressure-management questions, so choose the exact appliance before finalising the pipework.

Start here: estimate daily consumption and refill opportunities, choose the storage layout, then work through pumps, outlets, hot water and waste handling. Build in a drain and winterisation plan from the outset, especially if any parts sit outside the heated living area. Test for leaks using the equipment instructions before closing access and check again after the first journeys. Keep records of cleaning and maintenance. Use the electrical calculator for pump and water-heating demand where relevant, and the conversion budget tool for tanks, fittings, labour and maintenance access. The guides below take these linked decisions one at a time.