Overview

A toilet is a plumbing fixture that provides a controlled interface for the safe collection and conveyance of urine and feces, typically through a bowl, a water seal (trap), and a drain leading to on-site or sewered treatment systems. In buildings, toilets form part of the broader Plumbing system, with traps that retain water to block sewer gases from entering occupied spaces. Common materials include porcelain or vitreous china due to their chemical stability and cleanability, with stainless steel used in some institutional settings. Britannica.

Toilets are central to Sanitation strategies because they separate people from excreta and, when properly managed, interrupt fecal–oral disease transmission. As of August 2025, an estimated 3.4 billion people still lack safely managed sanitation, including 354 million who practice open defecation, underscoring persistent global inequalities in access. World Health Organization; UNICEF Data.

Principal types and technologies

• –Flush toilets (sewered): Gravity tank toilets discharge water from a cistern into the bowl to initiate siphonic or washdown evacuation; pressure-assisted models inject water at higher velocity; commercial “flushometer-valve” toilets use line pressure rather than a tank. These devices depend on a built-in trap to maintain a water seal. Britannica; U.S. EPA WaterSense; Department of Energy.
• –Dry/on-site toilets (non-sewered): Pit latrines, ventilated improved pit designs, and composting toilets collect and stabilize excreta in situ, often where water is scarce or sewerage is infeasible. The U.S. National Park Service describes composting toilets as waterless systems that promote aerobic decomposition within a ventilated chamber. National Park Service.
• –Vacuum toilets (specialized): Aircraft and certain rail/marine systems employ vacuum-assisted flushing that uses pressure differentials to move wastes into holding tanks with minimal water. HowStuffWorks.

How a water-flush toilet works

A typical residential flush toilet includes a cistern (tank), bowl, and an integral S/U-shaped trapway that retains a standing water seal. When actuated, stored water enters the bowl, raising the level until it spills over the trap’s weir, starting a siphon that evacuates bowl contents into the drain. The trap then refills to reestablish the gas seal. Sanitary fixture traps are a fundamental means of preventing sewer gases from entering buildings. Britannica.

Commercial flushometer-valve toilets omit the tank and meter a set volume through a valve driven by supply pressure, a configuration widely used in high-traffic settings and available in 1.1–1.6 gallon-per-flush models. U.S. EPA WaterSense; Sloan.

Materials and manufacture

Toilet bowls and tanks are commonly made from porcelain (vitreous china), which offers low porosity, chemical resistance, and durability; metal alternatives such as stainless steel are used where vandal resistance is needed. Britannica.

History

Archaeological and textual evidence indicates that ancient civilizations, including Rome and the Indus Valley, built latrines and drains that conveyed wastes away with flowing water, though these facilities did not achieve modern public-health outcomes. History.com.

In 1596, Sir John Harington described an early water closet with an overhead cistern and a flush mechanism; he reportedly installed a version for Queen Elizabeth I. Britannica; History.com.

In 1775, Alexander Cumming patented a flush toilet incorporating the S-trap that reliably sealed sewer gases—an essential step toward modern designs. Joseph Bramah improved the mechanism and obtained a British patent in 1778; the National Archives summarizes features of Bramah’s handle-operated water closet. History.com; The National Archives (UK).

Industrialization and urban sewer construction in the 19th century enabled broader adoption of flush toilets in Europe and North America, integrating fixtures with expanding sewer and Wastewater treatment systems. History.com.

Regulation and standards

In the United States, the Energy Policy Act of 1992 set national maximum flush volumes for water closets: 1.6 gallons per flush (gpf) for gravity tank, flushometer-tank, and electromechanical toilets manufactured after January 1, 1994; 1.6 gpf for most flushometer-valve toilets manufactured after January 1, 1997; and 3.5 gpf for blowout bowls. These requirements are codified at 42 U.S.C. §6295(k). LII/Cornell Law School.

The U.S. EPA’s voluntary WaterSense label certifies residential and commercial toilets that meet performance criteria and use no more than 1.28 gpf, i.e., 20% below the federal maximum; EPA notes that the program has paused the effective date of Version 2.0 while maintaining Version 1.2 in effect. U.S. EPA WaterSense; U.S. EPA WaterSense.

For non-sewered sanitation systems, ISO 30500 (Edition 2, 2025) specifies safety and performance requirements for prefabricated integrated units that collect and fully treat inputs without connection to sewers, including criteria for safe solid/liquid outputs and emissions. ISO; ANSI Sanitation.

Public health significance and global access

Safe toilets are a core determinant of health: WHO attributes hundreds of thousands of deaths annually to unsafe sanitation and broader WASH deficits, with poor sanitation linked to diarrheal diseases and other infections. World Health Organization.

According to the WHO/UNICEF Joint Monitoring Programme update released during World Water Week 2025, 3.4 billion people still lack safely managed sanitation, and 1.7 billion lack basic hygiene at home; rural areas lag behind urban areas. World Health Organization; UNICEF Data.

Environmental aspects and water use

In typical U.S. homes, toilets account for nearly 30% of indoor water use. Replacing older models (≥3.5 or ~5 gpf) with WaterSense-labeled toilets (≤1.28 gpf) can substantially reduce water consumption. U.S. EPA WaterSense; U.S. EPA WaterSense Calculator.

Globally, sanitation must be coupled with safe conveyance and treatment: WHO reports that in 2020, about 44% of household wastewater was discharged without safe treatment, highlighting the necessity of effective Wastewater treatment to realize health and environmental benefits. World Health Organization.

Dry and non-sewered options

Dry options remain essential where sewers and water are limited. Composting toilets, long used in parks and remote sites, are waterless systems that create conditions for aerobic decomposition and require carbon bulking material and ventilation; outputs must be handled and disposed or reused per applicable rules. National Park Service. ISO 30500 provides performance benchmarks for modern non-sewered systems that fully treat waste on site. ISO.

Cultural practices and related fixtures

Toilets are often used with cleansing practices that vary culturally, including water-based anal cleansing and the use of bidets, which are distinct fixtures for post-defecation hygiene. U.S. EPA WaterSense (context on toilets); see also World Health Organization for sanitation and hygiene context.

Internal cross-references

This article cross-references: Sanitation, Plumbing, Wastewater treatment, World Health Organization, United States Environmental Protection Agency, and Sir John Harington.