Activity 4.8.1:  Almost all structures used as a residence or business must have a water supply. If the water is used for drinking water, it is considered potable. Water is also used for such things as, bathing, toilets, cleaning, food preparation, cooling, fire protection, and industrial processes. Regardless of the intended use of the water, the source of public and private water supply is typically limited to groundwater aquifers or surface water. Wells are constructed into the aquifer, and pumps are used to remove the water. Civil (water resource) engineers work closely with hydrogeologists to develop groundwater supplies for communities. In fact, groundwater is the primary source of drinking water in the United States. The other major source of water is surface sources, such as lakes, reservoirs, or rivers. Rivers can be dammed to create a reservoir, which is essentially a constructed lake, behind the actual dam structure. Civil engineers of many different types (i.e., structural, geotechnical, water resource, hydrologic and hydraulic) are employed on such large projects.

After water is collected from a groundwater aquifer or a surface water source, it must be treated before it can be distributed to the community. Environmental engineers, another discipline within the field of civil engineering, design water treatment plants.

After treatment, water is pumped to nearby users and to a storage tank. Storage tanks serve two purposes: storage and water pressure. The tanks store water so that the water treatment plants do not have to make continuous modifications to the treatment processes to satisfy changes in water demand throughout the day. The second purpose of a storage tank is to provide pressure to the water distribution system. Pressure is the force that delivers the water, at a sufficient flowrate, to every part of the community.

Activity 4.8.2:  As urban centers grew in size, it became apparent that dumping raw sewage into streets, creeks, rivers, and lakes ultimately threatened the drinking water supply. The concept of wastewater management was born.

Once water has entered a structure, it is inevitable that the water will be used and the quality changed–usually for the worse. This is called wastewater. The constituents (impurities) within wastewater are dependent upon how the water was used.

Sanitary wastewater is generally accepted to consist of human waste, household cleaning solutions, oil, and grease from cooking activities, and small solid particles from garbage grinders or soil from cleaning clothes and floors. Wastewater from commercial establishments may include metals, strong acids and bases, cleaning solvents, oil and grease, and grit (small plastic, glass, stone, or metal particles), in addition to sanitary wastewater. Sometimes water is used for cooling purposes; thermal pollution is created and must be managed correctly.

A civil (environmental) engineer must decide how to manage the wastewater by considering three broad categorical options:

·        Reuse: wastewater that can be used again without treatment of any kind.

·        Recycling: wastewater that is treated either on-site or off-site and used again. 

·        Discharge/treatment: wastewater that is simply discharged from the structure for treatment either on-site or off-site.