A dual flush toilet is a variation of the flush toilet that uses two buttons or a handle mechanism to flush different amounts of water.
The purpose of this mechanism is to reduce the volume of water used to flush different types of waste. The design takes advantage of the fact that liquid waste requires a lesser amount of water to flush than solid waste.
The system was developed by Japanese sanitary product manufacturer TOTO in 1960. [1] It was equipped with two levers and built-in hand-washer, and also notable in that it reused the water in the hand-washer for flushing. However, it was not very commercially successful either in Japan or internationally. In 1976, American industrial designer Victor Papanek proposed the dual flush system in his book Design for the real world, [2] but the first practical implementation was designed in 1980, by staff at the Australian sanitary-ware company Caroma, with flush volumes of 11 and 5.5 litres. [3] The design caught on, and a redesign in 1994 cut water usage to 6 and 3 litres. [3]
The dual-flush toilet has become almost universally adopted in Australia, New Zealand, Singapore, Sweden, Israel and many other countries, with its use in new buildings often mandated by legislation in those countries. [4] The more complex dual-flush mechanism is more expensive than many other types of low-flush toilets. [5]
Due to being a development of the traditional Australian flush toilet, the dual-flush toilet differs from siphon-flush toilets in that it relies on gravity to remove waste from the toilet. The lack of siphoning also means that the toilet requires less water to operate. [5] Due to this, the waterline is considerably lower than that in siphon-flush toilets.
The toilet has two buttons on the cistern rather than the single-flush one; one button delivers a lesser amount of water (eg. 3 litres) and the other a greater amount (eg. 6 litres). [6] It also uses a larger 10 cm trapway in the bowl, allowing for water to come out faster and clear the bowl efficiently. [6]
There are also dual-flush toilets that use a siphon valve operated by a lever rather than buttons, with a ≤ 6L full flush, and a ≤ 3L half-flush if the flush handle is held down [7] or released immediately after flushing. [8]
The tipping bucket cistern can operate in a dual flush mode when the lever is rotated halfway 2.5/5 litre. [9]
The dual-flush toilet typically uses less water, resulting in lower running costs and less environmental impact. It was promoted by the Australian Government under its "Target 155" campaign. [10] The first dual-flush toilets had a 4.5 litre (half) and 9 litre (full) flush, but innovations by Caroma brought that down to 3 litres and 4.5 litres respectively, achieving a WELS rating of 4 and 5 stars in Australia.[ citation needed ]
Australian governments have used rebates to encourage the replacement of old single-flush toilets with more water-efficient ones. [11] For dual-flush toilets, with a star rating of 4 or higher, owners may be able to qualify to claim a rebate from the State Government in Victoria, [12] New South Wales, The ACT or South Australia.
In Britain, the cost of a dual-flush mechanism which can be retro-fitted to an existing toilet was estimated to be from about £15 in 2007. [13]
While dual flush reduces running cost, the initial purchase price is higher, and replacing a toilet entails installation cost. In many cases, it is possible to replace the flushing mechanism of an existing installation; such retrofitting can cost about US$30. [5] [14]
In the United States, the Energy Policy Act was signed into law in 1992 and took effect in 1994, requiring that toilets sold use no more than 6 litres (1.6 US gal) per flush. Fixtures that use a maximum of 20% less than the federally mandated maximum of 6 litres (1.6 US gal) receive the WaterSense label, a US Environmental Protection Agency (EPA) program designed to encourage water efficiency in the United States. [15]
For dual-flush toilets to receive this label, the average flushing volume of two reduced flushes and one full flush must be below 4.8 litres (1.28 US gal). [16]
While all dual-flush toilets are commonly seen as water-saving, this does not apply to all designs. In the US, some dual-flush toilets have flushes of 1.6 and 1.28 US gallons (6.1 and 4.8 L), which do not fulfill criteria for the WaterSense label and thus cannot be classified as high-efficiency toilets. [17] Based on the WaterSense averaging rule over two reduced flushes and one full flush, a dual-flush toilet with a full flush at the US legal maximum of 1.6 US gallons (6.1 L) must have a reduced flush of 1.12 US gallons (4.2 L) or less to meet the WaterSense standard of 1.28 US gallons (4.8 L) on average. [16] A common combination for dual-flush toilets meeting the WaterSense standard is a reduced flush of 1.1 US gallons (4.2 L) and a full flush of 1.6 US gallons (6.1 L). [18] [19]
Dual flush mechanisms are also more likely to develop leaks than a traditional siphon; the UK supplier Thames Water claimed in 2020 that dual flush toilets were likely to be wasting more water than they save due to a combination of leaks and confusion over which button to press. [20]
Greywater refers to domestic wastewater generated in households or office buildings from streams without fecal contamination, i.e., all streams except for the wastewater from toilets. Sources of greywater include sinks, showers, baths, washing machines or dishwashers. As greywater contains fewer pathogens than blackwater, it is generally safer to handle and easier to treat and reuse onsite for toilet flushing, landscape or crop irrigation, and other non-potable uses. Greywater may still have some pathogen content from laundering soiled clothing or cleaning the anal area in the shower or bath.
Sustainable living describes a lifestyle that attempts to reduce the use of Earth's natural resources by an individual or society. Its practitioners often attempt to reduce their ecological footprint by altering their home designs and methods of transportation, energy consumption and diet. Its proponents aim to conduct their lives in ways that are consistent with sustainability, naturally balanced, and respectful of humanity's symbiotic relationship with the Earth's natural ecology. The practice and general philosophy of ecological living closely follows the overall principles of sustainable development.
A flush toilet is a toilet that disposes of human waste by using the force of water to flush it through a drainpipe to another location for treatment, either nearby or at a communal facility, thus maintaining a separation between humans and their waste. Flush toilets can be designed for sitting or squatting, in the case of squat toilets. Most modern sewage treatment systems are also designed to process specially designed toilet paper. The opposite of a flush toilet is a dry toilet, which uses no water for flushing.
Water conservation includes all the policies, strategies and activities to sustainably manage the natural resource of fresh water, to protect the hydrosphere, and to meet the current and future human demand. Population, household size and growth and affluence all affect how much water is used. Factors such as climate change have increased pressures on natural water resources especially in manufacturing and agricultural irrigation. Many countries have already implemented policies aimed at water conservation, with much success. The key activities to conserve water are as follows: any beneficial reduction in water loss, use and waste of resources, avoiding any damage to water quality; and improving water management practices that reduce the use or enhance the beneficial use of water. Technology solutions exist for households, commercial and agricultural applications. Water conservation programs involved in social solutions are typically initiated at the local level, by either municipal water utilities or regional governments.
A plumbing fixture is an exchangeable device which can be connected to a plumbing system to deliver and drain water.
A urinal is a sanitary plumbing fixture for urination only. Urinals are often provided in public toilets for male users in Western countries. They are usually used in a standing position. Urinals can be with manual flushing, automatic flushing, or without flushing, as is the case for waterless urinals. They can be arranged as single sanitary fixtures or in a trough design without privacy walls. Urinals designed for females also exist but are rare. It is possible for females to use stand-up urinals using a female urination device.
Toilets in Japan are sometimes designed more elaborately than toilets commonly seen in other developed nations. European toilets occasionally have a separate bidet whilst Japan combines an electronic bidet with the toilet. The current state of the art for Western-style toilets in Japan is the bidet toilet, which as of March 2016 is installed in 81% of Japanese households. In Japan, these bidets are commonly called washlets, a brand name of Toto Ltd., and they may include many advanced features rarely seen outside of Asia. The basic feature set commonly found on washlets consists of anal hygiene, bidet washing, seat warming, and deodorization.
A composting toilet is a type of dry toilet that treats human waste by a biological process called composting. This process leads to the decomposition of organic matter and turns human waste into compost-like material. Composting is carried out by microorganisms under controlled aerobic conditions. Most composting toilets use no water for flushing and are therefore called "dry toilets".
A ballcock is a mechanism or machine for filling water tanks, such as those found in flush toilets, while avoiding overflow and backflow. The modern ballcock was invented by José Antonio de Alzate y Ramírez, a Mexican priest and scientist, who described the device in 1790 in the Gaceta de Literatura Méxicana. The ballcock device was patented in 1797 for use in steam engines by Edmund Cartwright.
A pit latrine, also known as pit toilet, is a type of toilet that collects human waste in a hole in the ground. Urine and feces enter the pit through a drop hole in the floor, which might be connected to a toilet seat or squatting pan for user comfort. Pit latrines can be built to function without water or they can have a water seal. When properly built and maintained, pit latrines can decrease the spread of disease by reducing the amount of human feces in the environment from open defecation. This decreases the transfer of pathogens between feces and food by flies. These pathogens are major causes of infectious diarrhea and intestinal worm infections. Infectious diarrhea resulted in about 700,000 deaths in children under five years old in 2011 and 250 million lost school days. Pit latrines are a low-cost method of separating feces from people.
A cistern is a waterproof receptacle for holding liquids, usually water. Cisterns are often built to catch and store rainwater. Cisterns are distinguished from wells by their waterproof linings. Modern cisterns range in capacity from a few litres to thousands of cubic metres, effectively forming covered reservoirs.
Water efficiency is the practice of reducing water consumption by measuring the amount of water required for a particular purpose and is proportionate to the amount of essential water used. Water efficiency differs from water conservation in that it focuses on reducing waste, not restricting use. Solutions for water efficiency not only focus on reducing the amount of potable water used but also on reducing the use of non-potable water where appropriate. It also emphasizes the influence consumers can have on water efficiency by making small behavioral changes to reduce water wastage, and by choosing more water-efficient products.
A flushing trough is a long cistern which serves several toilet pans. It is designed to allow a shorter interval between flushes than individual cisterns.
A low-flush toilet is a flush toilet that uses significantly less water than traditional high-flow toilets. Before the early 1990s in the United States, standard flush toilets typically required at least 3.5 gallons per flush and they used float valves that often leaked, increasing their total water use. In the early 1990s, because of concerns about water shortages, and because of improvements in toilet technology, some states and then the federal government began to develop water-efficiency standards for appliances, including toilets, mandating that new toilets use less water. The first standards required low-flow toilets of 1.6 gallons per flush. Further improvements in the technology to overcome concerns about the initial poor performance of early models have further cut the water use of toilets and while federal standards stagnate at 1.6 gallons per flush, certain states' standards toughened up to require that new toilets use no more than 1.28 gallons per flush, while working far better than older models. Low-flush toilets include single-flush models and dual-flush toilets, which typically use 1.6 US gallons per flush for the full flush and 1.28 US gallons or less for a reduced flush.
A toilet is a piece of sanitary hardware that collects human urine and feces, and sometimes toilet paper, usually for disposal. Flush toilets use water, while dry or non-flush toilets do not. They can be designed for a sitting position popular in Europe and North America with a toilet seat, with additional considerations for those with disabilities, or for a squatting posture more popular in Asia, known as a squat toilet. In urban areas, flush toilets are usually connected to a sewer system; in isolated areas, to a septic tank. The waste is known as blackwater and the combined effluent, including other sources, is sewage. Dry toilets are connected to a pit, removable container, composting chamber, or other storage and treatment device, including urine diversion with a urine-diverting toilet.
Urine diversion, also called urine separation or source separation, refers to the separate collection of human urine and feces at the point of their production, i.e. at the toilet or urinal. Separation of urine from feces allows human waste to be treated separately and used as a potential resource. Applications are typically found where connection to a sewer-based sanitation system is not available or areas where water supplies are limited.
A flushometer is a metal water-diverter that uses an inline handle to flush tankless toilets or urinals. It was invented by William Elvis Sloan and is a product of the Sloan Valve Company.
Niagara Conservation is a manufacturing company based in Fort Worth, Texas best known for its plumbing products and its water conservation efforts. Niagara Conservation also manufactures lighting fixtures, light bulbs, caulks, sealants, and weatherization products.
Residential water use includes all indoor and outdoor uses of drinking quality water at single-family and multifamily dwellings. These uses include a number of defined purposes such as flushing toilets, washing clothes and dishes, showering and bathing, drinking, food preparation, watering lawns and gardens, and maintaining swimming pools. Some of these end uses are detectable while others are more difficult to gauge.
A low-flow fixture is a water saving plumbing fixture designed to achieve water savings by having a lower flow rate of water or a smaller quantity per flush. Some of these low-flow fixtures are faucets, showerheads, and toilets. In the United States a maximum water usage of conventional plumbing fixtures was federally mandated by the Energy policy act of 1992. Low-flow fixtures are designed to save water over conventional fixtures by having a lower flow rate while still maintaining satisfactory performance. The Environmental protection agency (EPA) WaterSense program has requirements for plumbing fixtures to achieve their definition for water saving low-flow.
Because what one does while sitting on a toilet differs in both quantity and quality, it seemed simple to redesign the apparatus so that one could select whether a great deal or only a minimal amount of water was needed for flushing. This concept again was rejected by my client - a man who makes his living manufacturing toilet bowls - as being 'in bad taste'
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