question: To what degree does the daily use of cleaning products like soap and shampoo affect the state of water in a major city, and where does it go after entering the drain?
comment: The best explanation for a 5yo would start with a description of how all of the pipes from city plumbing eventually lead to a wastewater treatment plant. Then a picture would be better than a thousand words - > URL_0 Explaining each step would be complicated, but they’d understand that the waste water goes through many steps before it’s ready for reuse. The cleaning products are removed in the secondary processing, after the solid waste and particles are removed. They are particularly easy to remove, as the law requires them to be. Oil, gasoline, and toxic liquids are removed afterwards, are much more difficult to remove, and are illegal to dump in your waste water. It’s too bad that this particular picture doesn’t show the methane being collected and used as fuel by the plant, as a 5yo would probably think that’s cool
passages: As of 2018, EPA and state water quality agencies have estimated that urban runoff is a probable source of impairment for at least of rivers and streams; of lakes, reservoirs and ponds; and of coastal shoreline.
  
  Section::::Industrial pollution.
  
  Some narratives based on observations of industrial waste discharged to certain rivers and harbors were first reported in the 1870s, as the industrial revolution expanded throughout the United States and its environmental impacts were observed more frequently.
  
  Section::::Industrial pollution.:Growth of industrialization and industrial waste.
   Drinking water does not represent a significant source of exposure in comparison to other sources such as food packing materials, cleaning products, and various skin care products. Concentrations of nonylphenol in treated drinking water varied from 85 ng/L in Spain to 15 ng/L in Germany.
  
  Microgram amounts of nonylphenol have also been found in the saliva of patients with dental sealants.
  
  Section::::Human health hazards.:Human exposure and breakdown.:Breakdown.
   BULLET::::5. Filtration: Settled water from the sedimentation basins is treated with a filter aid polymer and enters the filters, which consist of layers of anthracite coal, sand, and gravel filter media. The filters remove smaller particles from the water as well as larger particles that did not settle during the sedimentation process.
   Plastic bottles, plastic bags, inflatable toys, baseballs and environmental debris like tree limbs, are all skimmed from the waterways and deposited into oversized dumpsters for removal. In decades past, there used to be larger items, such as sofas and refrigerators. But over the years, the skimmer boats have removed most of those. Still, there is the occasional unlikely item, such as the live deer that was recently rescued to dry ground.
   Use of public supply water by manufacturing category varies greatly across U.S. cities depending on the presence (or absence) of water-intensive manufacturing plants and the availability of local sources of water supply. The available data indicate shares of 9 percent in Tampa, Florida and New York City; 15 percent in Austin, Texas, 21 percent in Oakland, California (East Bay MUD) and 13 percent in North Carolina. In the U.S. there are 170,169 manufacturing establishments with a combined floor space of 11,100 million square feet. Most large manufacturing plants have their own source of water supply and purchase some amounts of drinking quality water from public systems. In 2010, the self-supplied industrial use (excluding thermoelectric plants and mining) was 15,900 mgd. The amount purchased from public systems was reported to be 4,750 mgd in 1995 (or about 40 percent of total CII use). Based on the total floor space of 11,100 million square feet in manufacturing buildings in the U.S. and assuming average use of 215 g/ksf/d, the total use of publicly-supplied water by the CII manufacturing category in the U.S. would be about 2,400 mgd or about 20 percent of the total CII use.
   Municipal and industrial wastewater are typically treated at wastewater treatment plants. Mitigation of polluted surface runoff is addressed through a variety of prevention and treatment techniques. ("See" Surface runoff#Mitigation and treatment.)
  
  Section::::Effects on human civilization.:Human uses.:Industrial applications.
   Chemical use and handling. Following enactment of the U.S. Resource Conservation and Recovery Act (RCRA) in 1976, and later the Water Quality Act of 1987, states and cities have become more vigilant in controlling the containment and storage of toxic chemicals, thus preventing releases and leakage. Methods commonly applied are: requirements for double containment of underground storage tanks, registration of hazardous materials usage, reduction in numbers of allowed pesticides and more stringent regulation of fertilizers and herbicides in landscape maintenance. In many industrial cases, pretreatment of wastes is required, to minimize escape of pollutants into sanitary or stormwater sewers.
   Data shows that United States has more than 35,000 laundries. On the average, a single laundry can discharge 400 m of wastewater every day. Annually, about 5.11 km laundry wastewater is produced, which can fill 1,460 Superdomes in New Orleans.
  
  Section::::General influences of laundry wastewater.:Treatment of laundry wastewater.
  
  There are several parameters in the evaluation of laundry wastewater: temperature, pH-value, suspended substances, Cl, sediment substances, total nitrogen, total phosphorus, nitrogen ammonia, chemical oxygen demand(COD), biochemical oxygen demand(BOD), anionic surfactants.
  
  Section::::General influences of laundry wastewater.:Chemicals in detergents.
   Section::::Wastewater.
  
  Wastewater from various appliances, fixtures, and taps is transferred to the waste and sewage removal system via the sewage drain system to treatment plants. This system consists of larger diameter piping, water traps, and ventilation to prevent toxic gases from entering the living space.
  
  Section::::Water flow reduction.
  
  Water flow through a tap can be reduced by inexpensive small plastic flow reducers. These restrict flow between 15 and 50%, aiding water conservation and reducing the burden on both water supply and treatment facilities.
  
  Section::::Comparison to bottled water.
   Contaminated storm water washed off of parking lots, roads and highways, called urban runoff, is sometimes included under the category of non-point sources. This runoff becomes a point source because it is typically channeled into storm drain systems and discharged through pipes to local surface waters.
  
  Section::::Contaminants and their sources.
   In some areas, especially along the U.S. coast, polluted runoff from roads and highways may be the largest source of water pollution. For example, about 75 percent of the toxic chemicals getting to Seattle, Washington's Puget Sound are carried by stormwater that runs off paved roads and driveways, rooftops, yards, and other developed land.
   One possibility is that the water is sent to a waste management facility to be treated and then recirculated. However, experts have found that sewage treatment does not remove these chemicals completely from drinking supplies. Any type of water that is flushed down the shower, toilet, or sink usually carries with it some sort of EDC. These drains lead to pipes that lead to a waste water management plant. A typical waste water treatment plant involves a multiple step process of water cleaning but due to the microscopic size of EDC particles, it usually isn't a 100% successful process. For example, Boulder, Colorado Waste Water Management receives water in inceptor pipes, which lead into larger holding pools at the facility. The typical treatment usually lasts between 12 and 24 hours and consists of three main treatment processes. First, physical treatments remove solid and organic materials from the waste water. Then, microbiological treatments follow. Bacteria in these waste tanks feed on carbon and nitrogenous compounds left in the sewage. And finally, the water is treated with ultraviolet blue light to disinfect the remaining water. The effluent water is feed back into local creeks, streams, and freshwater resources. This basic waste water treatment plan is effective in targeting larger contaminants, however, it is ineffective in removing microscopic EDCs. Thus, EDC micro-pollution is causing a toxic buildup of chemical soups in freshwater habitats.
   Water utilities often adopt water efficiency programs that are directed specifically to CII customers. The programs often target the largest water users as well as specific categories of CII customers including government and municipal buildings, large landscape areas, schools and colleges, office buildings, restaurants and hotels. Water use information in these and other readily recognizable functional classes of CII users from several studies of the CII sector are briefly characterized below.
  
  Section::::Water use in major CII categories.
  
  Section::::Water use in major CII categories.:Office buildings.
   BULLET::::- Landfills and waste dumps: Modern landfills are designed to contain any leaking liquids, but floods can carry conaminants over the barriers. Older dumpsites may have a wide variety of pollutants that can seep into ground water.
  
  BULLET::::- Household wastes: Improper disposal of many common products can pollute ground water. These include cleaning solvents, used motor oil, paints, and paint thinners. Even soaps and detergents can harm drinking water. These are often a problem from faulty septic tanks and septic leaching fields.
   Pollutant concentration levels are influenced by the age and condition of the collection system and the amount of infiltration/inflow in comparison to the sanitary flow. Pollutant concentration peaks depend on size and slope of the piping system, time interval between storms, and solids accumulation in the collection system. Steeper sewer gradients and pipe bottom shapes that maintain high velocity flow during low-flow conditions will reduce sediment accumulation in sewers; and periodic sewer flushing of individual lines during dry weather may move accumulated solids to the wastewater treatment plant before stormwater runoff causes simultaneous peak flow in the entire collection system.
   The problem was addressed in 2004 by adding additional treatments to the water, preventing the chloramine from dissolving lead in the water mains, solder joints, and plumbing fixtures.
  
  In 2010, the CDC reported that 15,000 homes in the Washington, D.C. area might still have water supplies with dangerous levels of lead.
  
  Section::::2001–2004: Initial reports of elevated lead.
   In the 1972 CWA, Congress created a major public works financing program for building and upgrading sewage treatment plants. This grant program was transitioned to a low-interest loan program in the 1987 amendments to the act. Ideally, the municipal wastewater treatment process comprises three stages:
  
  BULLET::::- Primary treatment: Physical processes that remove conventional pollutants: 60 percent of suspended solids and 30 percent oxygen-demanding waste; as well as 20 percent of nitrogen compounds;
   When anthropogenic contaminants are dissolved or suspended in runoff, the human impact is expanded to create water pollution. This pollutant load can reach various receiving waters such as streams, rivers, lakes, estuaries and oceans with resultant water chemistry changes to these water systems and their related ecosystems.
  
  A 2008 report by the United States National Research Council identified urban stormwater as a leading source of water quality problems in the U.S.
   In 1991, the city of Burbank was sued by the EPA for allowing companies to exceed discharge limits into the channel. Leading pollutants in the stream include algae, ammonia, cadmium, odors, unnatural scum/foam, and trash.
  
  Under the American Recovery and Reinvestment Act of 2009, the U.S. Army Corps of Engineers has planned to allocate $700,000 to repair the channel wall which is "currently in danger of failing."
   As stormwater is channeled into storm drains and surface waters, the natural sediment load discharged to receiving waters decreases, but the water flow and velocity increases. In fact, the impervious cover in a typical city creates five times the runoff of a typical woodland of the same size.
  
  Section::::Effects.
  
  A 2008 report by the United States National Research Council (textbox below) identified urban runoff as a leading source of water quality problems.
   Nationwide, there are approximately 1,012 thousand office buildings with a combined floor space of 1,952 million square feet. Assuming the WUI of 88 g/ksf/d as representing average office usage in the U.S., the total country-wide use would be 1,400 mgd or close to 12 percent of CII use. Significant quantities of water can be saved in older office buildings by replacing bathroom fixtures, cooling tower efficiency retrofits, and adopting efficient landscape irrigation measures. Estimates of potential water conservation savings range from 19 percent in Southwest Florida to 30 percent or more in California.
  
  Section::::Water use in major CII categories.:Retail outlets.
   BULLET::::- 11% was from local groundwater, a resource that is actively managed and allocated, but is continually being threatened by chemical pollutants, such as MTBE and perchlorates;
  
  BULLET::::- 1% came from recycled water and was used for irrigation, recreation, and industrial purposes.
  
  The use of water from specific sources can vary greatly from year to year.
   Section::::Definitions.
  
  Section::::Definitions.:Primary treatment.
  
  Primary treatment of sewage by quiescent settling allows separation of floating material and heavy solids from liquid waste. The remaining liquid usually contains less than half of the original solids content and approximately two-thirds of the BOD in the form of colloids and dissolved organic compounds. Where nearby water bodies can rapidly dilute this liquid waste, primary treated sewage may be discharged so natural biological decomposition oxidizes remaining waste.
  
  The city of San Diego used Pacific Ocean dilution of primary treated effluent into the 21st century.
  
  Section::::Definitions.:Secondary treatment.
   There is debate about possible health and environmental effects. To address these concerns, A Risk Assessment Study of potential health risks of recycled water and comparisons to conventional Pharmaceuticals and Personal Care Product (PPCP) exposures was conducted by the WateReuse Research Foundation. For each of four scenarios in which people come into contact with recycled water used for irrigation - children on the playground, golfers, and landscape, and agricultural workers - the findings from the study indicate that it could take anywhere from a few years to millions of years of exposure to nonpotable recycled water to reach the same exposure to PPCPs that we get in a single day through routine activities.
   In order to achieve improvements in the efficiency of CII water use, it is necessary to obtain information about the existing conservation potential in different types of establishments and about specific end uses of water in each CII category. Studies of water use in the CII sector were conducted by the American Water Works Association, Pacific Institute, Colorado WaterWise Council, Conserve Florida Water Clearinghouse (CFWC), and Water Research Foundation (WRF).
  
  Section::::CII user categories and subcategories.
  