Surface water supplies, problems and solutions; the small farm dam how to construct one; well drilling the von der Rigg; spring and groundwater protection; urban water supply and sanitation; water vending; roof catchment systems.

• 地表水供给的问题与解决方法；如何建造农场小蓄水池；凿井；泉水与地下水的保护；城市供水与卫生设备；水的销售；屋顶排水系统。