Design and construction Water-supply engineering Purification 4 Sewage 4 Hydraulic machinery 3 Pumping machinery 3 Water 3 mer ... Equipment and supplies 2 Hydraulics 2 Materials 2 Materials handling 2 Piping 2 Plumbing 2 Refrigeration and refrigerating machinery 2 Sewage disposal 2 Sewerage 2 Slurry pipelines 2 Storm sewers 2 Water quality management 2 Water-supply 2 Actuators 1 Air 1 Air conditioning 1 Air-compressors 1 Airborne infection 1 Artificial groundwater recharge 1 Ash disposal 1 Automatic control 1 Bearings (Machinery) 1 Belts and belting 1 mindre ...