Sewerage is the infrastructure that conveys sewage or surface runoff using sewers. It encompasses components such as receiving drains, manholes, pumping stations, storm overflows, and screening chambers of the combined sewer or sanitary sewer. Sewerage ends at the entry to a sewage treatment plant or at the point of discharge into the environment. It is the system of pipes, chambers, manholes or inspection chamber, etc. that conveys the sewage or storm water.
Water pollution is the contamination of water bodies, with a negative impact on their uses. It is usually a result of human activities. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water pollution results when contaminants mix with these water bodies. Contaminants can come from one of four main sources. These are sewage discharges, industrial activities, agricultural activities, and urban runoff including stormwater. Water pollution may affect either surface water or groundwater. This form of pollution can lead to many problems. One is the degradation of aquatic ecosystems. Another is spreading water-borne diseases when people use polluted water for drinking or irrigation. Water pollution also reduces the ecosystem services such as drinking water provided by the water resource.
A sanitary sewer is an underground pipe or tunnel system for transporting sewage from houses and commercial buildings to a sewage treatment plant or disposal.
The District of Columbia Water and Sewer Authority(DC Water) provides drinking water, sewage collection, and sewage treatment for Washington, D.C. The utility also provides wholesale wastewater treatment services to several adjoining municipalities in Maryland and Virginia, and maintains more than 9,000 public fire hydrants in Washington, D.C.
A combined sewer is a type of gravity sewer with a system of pipes, tunnels, pump stations etc. to transport sewage and urban runoff together to a sewage treatment plant or disposal site. This means that during rain events, the sewage gets diluted, resulting in higher flowrates at the treatment site. Uncontaminated stormwater simply dilutes sewage, but runoff may dissolve or suspend virtually anything it contacts on roofs, streets, and storage yards. As rainfall travels over roofs and the ground, it may pick up various contaminants including soil particles and other sediment, heavy metals, organic compounds, animal waste, and oil and grease. Combined sewers may also receive dry weather drainage from landscape irrigation, construction dewatering, and washing buildings and sidewalks.
Sanitary sewer overflow (SSO) is a condition in which untreated sewage is discharged from a sanitary sewer into the environment prior to reaching sewage treatment facilities. When caused by rainfall it is also known as wet weather overflow. Causes of sanitary sewer overflows include: Blockage of sewer lines, infiltration/Inflow of excessive stormwater into sewer lines during heavy rainfall, malfunction of pumping station lifts or electrical power failure, broken sewer lines. Prevention of such overflow events involves regular maintenance and timely upgrades of infrastructure.
Dallas Water Utilities (DWU) is the water and wastewater service operated by the City of Dallas, Texas, in the United States. DWU is a non-profit City of Dallas department that provides services to the city and 31 nearby communities, employs approximately 1450 people, and consists of 26 programs. DWU's budget is completely funded through the rates charged for water and wastewater services provided to customers. Rates are based on the cost of providing the services. The department does not receive any tax revenues. Primary authority and rules for the department are listed in Chapter 49Archived 2006-10-04 at the Wayback Machine of the Dallas City Code.
Water supply and sanitation in the United States involves a number of issues including water scarcity, pollution, a backlog of investment, concerns about the affordability of water for the poorest, and a rapidly retiring workforce. Increased variability and intensity of rainfall as a result of climate change is expected to produce both more severe droughts and flooding, with potentially serious consequences for water supply and for pollution from combined sewer overflows. Droughts are likely to particularly affect the 66 percent of Americans whose communities depend on surface water. As for drinking water quality, there are concerns about disinfection by-products, lead, perchlorates, PFAS and pharmaceutical substances, but generally drinking water quality in the U.S. is good.
Sewage treatment is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable to discharge to the surrounding environment or an intended reuse application, thereby preventing water pollution from raw sewage discharges. Sewage contains wastewater from households and businesses and possibly pre-treated industrial wastewater. There are a high number of sewage treatment processes to choose from. These can range from decentralized systems to large centralized systems involving a network of pipes and pump stations which convey the sewage to a treatment plant. For cities that have a combined sewer, the sewers will also carry urban runoff (stormwater) to the sewage treatment plant. Sewage treatment often involves two main stages, called primary and secondary treatment, while advanced treatment also incorporates a tertiary treatment stage with polishing processes and nutrient removal. Secondary treatment can reduce organic matter from sewage, using aerobic or anaerobic biological processes. A so-called quarternary treatment step can also be added for the removal of organic micropollutants, such as pharmaceuticals. This has been implemented in full-scale for example in Sweden.
A marine outfall is a pipeline or tunnel that discharges municipal or industrial wastewater, stormwater, combined sewer overflows (CSOs), cooling water, or brine effluents from water desalination plants to the sea. Usually they discharge under the sea's surface. In the case of municipal wastewater, effluent is often being discharged after having undergone no or only primary treatment, with the intention of using the assimilative capacity of the sea for further treatment. Submarine outfalls are common throughout the world and probably number in the thousands. The light intensity and salinity in natural sea water disinfects the wastewater to ocean outfall system significantly. More than 200 outfalls alone have been listed in a single international database maintained by the Institute for Hydromechanics at Karlsruhe University for the International Association of Hydraulic Engineering and Research (IAHR) / International Water Association (IWA) Committee on Marine Outfall Systems.
Water supply and sanitation in Israel are intricately linked to the historical development of Israel. Because rain falls only in the winter, and largely in the northern part of the country, irrigation and water engineering are considered vital to the country's economic survival and growth. Large scale projects to desalinate seawater, direct water from rivers and reservoirs in the north, make optimal use of groundwater, and reclaim flood overflow and sewage have been undertaken. Among them is the National Water Carrier, carrying water from the country's biggest freshwater lake, the Sea of Galilee, to the northern part of the Negev desert through channels, pipes and tunnels. Israel's water demand today outstrips available conventional water resources. Thus, in an average year, Israel relies for about half of its water supply on unconventional water resources, including reclaimed water and desalination. A particularly long drought in 1998–2002 had prompted the government to promote large-scale seawater desalination. In 2022, 85% of the country's drinkable water was produced through desalination of saltwater and brackish water.
Sewage is a type of wastewater that is produced by a community of people. It is typically transported through a sewer system. Sewage consists of wastewater discharged from residences and from commercial, institutional and public facilities that exist in the locality. Sub-types of sewage are greywater and blackwater. Sewage also contains soaps and detergents. Food waste may be present from dishwashing, and food quantities may be increased where garbage disposal units are used. In regions where toilet paper is used rather than bidets, that paper is also added to the sewage. Sewage contains macro-pollutants and micro-pollutants, and may also incorporate some municipal solid waste and pollutants from industrial wastewater.
Greater Mexico City, a metropolitan area with more than 19 million inhabitants including Mexico's capital with about 9 million inhabitants, faces tremendous water challenges. These include groundwater overexploitation, land subsidence, the risk of major flooding, the impacts of increasing urbanization, poor water quality, inefficient water use, a low share of wastewater treatment, health concerns about the reuse of wastewater in agriculture, and limited cost recovery. Overcoming these challenges is complicated by fragmented responsibilities for water management in Greater Mexico City:
Water supply and sanitation in Belgium is provided by a large variety of organizations: Most of the 581 municipalities of Belgium have delegated the responsibility for water supply and sanitation to regional or inter-municipal utilities. There are more than 62 water supply utilities, including 2 regional, 30 inter-municipal and 30 municipal utilities. Another 100 mostly small municipalities provide services directly without having a legally of financially separate entity for water supply. Water is not scarce in Belgium and water supply is generally continuous and of good quality. However, wastewater treatment has long lagged behind and Brussels only achieved full treatment of its wastewater in 2007. In 2004 the European Court of Justice ruled condemning Belgium's failure to comply with the EU wastewater directive, and the ruling has not been fully complied with so far. Wallonia satisfies 55% of the national needs in drinking water while it counts only 37% of the population. Flanders and Brussels are dependent on drinking water from Wallonia, at a level of 40% and 98% respectively.
Integrated urban water management in Medellín, Colombia is considered to be an overall success and a good example of how a large metropolitan area with moderate income disparity can adequately operate and maintain quality water supply to its many citizens. This is quite remarkable given the large urbanized population in the metropolitan area of the Aburrá Valley of 3.3 million, many of whom live on the slopes of the Aburrá Valley where Medellín is situated and highly prone to landslides and stormwater erosion. Sound urban water management within the metropolitan area of the Aburrá Valley is carried out by a set of technically strong institutions with financial independence—and lack of political interference such as Empresas Publicas de Medellin (EPM).
Water supply and sanitation in Turkey is characterized by achievements and challenges. Over the past decades access to drinking water has become almost universal and access to adequate sanitation has also increased substantially. Autonomous utilities have been created in the 16 metropolitan cities of Turkey and cost recovery has been increased, thus providing the basis for the sustainability of service provision. Intermittent supply, which was common in many cities, has become less frequent. In 2004, 61% of the wastewater collected through sewers was being treated. In 2020 77% of water was used by agriculture, 10% by households and the rest by industry.Charging for water used by agriculture has been suggested.
Water supply and sanitation in Japan is characterized by numerous achievements and some challenges. The country has achieved universal access to water supply and sanitation, has one of the lowest levels of water distribution losses in the world, regularly exceeds its own strict standards for the quality of drinking water and treated waste water, uses an effective national system of performance benchmarking for water and sanitation utilities, makes extensive use of both advanced and appropriate technologies such as the jōkasō on-site sanitation system, and has pioneered the payment for ecosystem services before the term was even coined internationally. Some of the challenges are a decreasing population, declining investment, fiscal constraints, ageing facilities, an ageing workforce, a fragmentation of service provision among thousands of municipal utilities, and the vulnerability of parts of the country to droughts that are expected to become more frequent due to climate change.
Water supply and sanitation in Lebanon is characterized by a number of achievements and challenges. The achievements include the reconstruction of infrastructure after the 1975–90 Civil War and the 2006 war with Israel, as well as the reform of the water and sanitation sector through a water law passed in 2000. The law created four Regional Water Establishments to consolidate numerous smaller utilities.
Water supply and sanitation in Georgia is characterized by achievements and challenges. Among the achievements is the improvement of water services in the capital Tbilisi where the water supply is now continuous and of good quality, major improvements in the country's third-largest city Batumi on the Black Sea where the country's first modern wastewater treatment plant now is under operation, as well as a general increase in access to drinking water in the entire country. Water and sewer tariffs remain affordable, with the private water company Georgian Water and Power (GWP) serving the capital being financially viable and profitable, while the public water company serving most of the rest of the country remains financially weak. The improvements were achieved after the Rose Revolution of 2004 when the government decided to reform the sector and to invest in it after many years of neglect.
Water supply and sanitation in the Wellington region involves the provision of the "three waters" – drinking water, stormwater, and wastewater services in the Greater Wellington region.
