Swedish motorhome experts warn that improper winter storage preparation can cause frost damage and costly repairs. Stefan Janeld of Allt om husbilen says the water system must be fully drained, including the toilet valve that many owners forget, and cabinets should be left open for ventilation. Jörgen Nyström of the Swedish Caravan and Motorhome Industry Association adds that water can remain in the grey water tank, shower hose and toilet flush, and recommends following the manufacturer's manual. According to Nyström, a frozen water pump costs around 1,500 kronor to replace and a water heater around 5,500 kronor, plus diagnostic and repair costs.