Instruct: Given a question, retrieve relevant documents that answer the question.
Query: When was fluorine first introduced in tap water?
Health and dental organizations worldwide have endorsed its safety and effectiveness.[3] Its use began in 1945, following studies of children in a region where higher levels of fluoride occur naturally in the water.[33] Further research showed that moderate fluoridation prevents tooth decay.[34]
Tap water is often culturally assumed to be drinking water, especially in developed countries. Usually it is potable, although water quality problems are not rare. Household water purification methods such as water filters, boiling, or distillation can be used when tap water's potability is doubted. The application of technologies (such as water treatment plants) involved in providing clean water to homes, businesses, and public buildings is a major subfield of sanitary engineering. Calling a water supply "tap water" distinguishes it from the other main types of fresh water which may be available; these include water from rainwater-collecting cisterns, water from village pumps or town pumps, water from wells, or water carried from streams, rivers, or lakes (whose potability may vary).
The reaction of pentafluorophenyl derivatives has been long puzzling for its mechanism. Independent of the substituent, they all exhibit a para directing effect. The new introduced group too has no effect on the directing behaviour. In all cases, a 1,4-disubstituted-2,3,5,6-tetrafluorobenzene derivative shows up. Finally, the clue is found not in the nature of the non-fluorine substituent, but in the fluorines themselves. The π-electropositive effect introduces electrons into the aromatic ring. The non-fluorine substituent is not capable of doing so. As charge accumulates at the "ortho" and "para" positions relative to the donating group, the "ortho" and "para"-positions relative to the non-fluorine substituent receive less charge, so are less negative or more positive. Furthermore, the non-fluorine substituent in general is more bulky than fluorine, so its "ortho"-positions are sterically shielded, leaving the "para"-position as the sole reaction site for anionic entering groups.
The main application of manganese tetrafluoride is in the purification of elemental fluorine. Fluorine gas is produced by electrolysis of anhydrous hydrogen fluoride (with a small amount of potassium fluoride added as a support electrolyte) in a Moissan cell. The technical product is contaminated with HF, much of which can be removed by passing the gas over solid KF, but also with oxygen (from traces of water) and possibly heavy-metal fluorides such as arsenic pentafluoride (from contamination of the HF). These contaminants are particularly problematic for the semiconductor industry, which uses high-purity fluorine for etching silicon wafers. Further impurities, such as iron, nickel, gallium and tungsten compounds, can be introduced if unreacted fluorine is recycled.
By 1970, Zip also installed the world's first "boiling water tap" – a boiling water tap (faucet) installed beside standard hot and cold taps. It provided steaming boiling water from an under-sink pressurised cylinder containing water heated to above boiling point. To conform to the safety maintenance requirements of Australian Standards, these models were superseded subsequently by unpressurised systems emitting minimal steam. 
By 1975, Zip complemented its early over-sink boiling water heaters with its first on-wall instant boiling water heaters with enhanced energy efficiency and an increased capacity measured in number of cups of boiling water per hour. These were followed closely by the introduction of the Zip Miniboil, the first truly small on-wall instant boiling water heater. It was a practical, space-saving addition to the smaller office or home kitchen. The Zip Miniboil was followed closely by the Zip Tea Tap, an under-sink, non-pressurized instant boiling water system. It delivered water within one degree of boiling point, with little or no steam, or the spatter, which characterised both the early Zip "boiling water tap" and some later boiling water systems, still marketed by competitors in the United Kingdom and Europe. The Zip Tea Tap originated a patented steam condensing system to eliminate the emission of excessive steam in conjunction with boiling water. By 1985, Zip Tea Tap was so well accepted in Australia that it was specified for all of the kitchens and Members' offices in the new Parliament House, Canberra, officially opened in 1988. 
Taps are normally connected to the water supply by means of a "swivel tap connector", which is attached to the end of the water pipe using a soldered or compression fitting, and has a large nut to screw onto the threaded "tail" of the tap, which hangs down underneath the bath, basin or sink. A fibre washer (which expands when wet, aiding the seal) is used between the connector and the tap tail. Tap tails are normally  " or 12 mm in diameter for sinks and  " or 19 mm for baths, although continental Europe sometimes uses a  " (still imperial) size. The same connection method is used for a ballcock.
Reactions with elemental fluorine are often sudden or explosive. Many substances that are generally regarded as unreactive, such as powdered steel, glass fragments, and asbestos fibers, are readily consumed by cold fluorine gas. Wood and even water burn with flames when subjected to a jet of fluorine, without the need for a spark.
In modern Western society, levels of contaminants found in tap water vary for every household and plumbing system but tend to be low. Two general conceptions with popular appeal are:
Both lack scientific support. In reality, both tap water and bottled water are usually safe, although in both cases exceptions can occur. The University of Cincinnati recently completed a Tap Water Quality Analysis, funded by PUR, for major US cities. Its findings show generally safe water quality in most regions. While most US cities have what is considered safe tap water, contaminants ranging from bacteria to heavy metals are present in some tap water, and occasionally serious violations of tap water standards have been well-publicized, such as the severe 1993 Cryptosporidium outbreak in Milwaukee, Wisconsin, which led to several deaths and around 400,000 illnesses (see: Milwaukee Cryptosporidium outbreak). Regarding bottled water quality perceptions and reality, in 1999, the Natural Resources Defense Council (NRDC) released controversial findings from a 4-year study on bottled water. The results of this study claimed that one-third of the waters tested contained levels of contamination—including synthetic organic chemicals, bacteria, and arsenic—in at least one sample that exceeded allowable limits under either state or bottled water industry standards or guidelines. However, the bottled water industry was quick to dispute the claim, saying bottled water is one of the most highly regulated food products under the FDA regulatory authority and that the FDA system worked extremely well when coupled with the International Bottled Water Association's Model Code and unannounced inspections.
Fluoride or fluorine deficiency is a disorder which may cause increased dental caries (or tooth decay, is the breakdown of dental tissues by the acidic products released by the "bacterial fermentation of dietary carbohydrates.") and possibly osteoporosis (a bone disorder which leads to a decrease in bone mass, and an increase in bone fragility), due to a lack of fluoride in the diet. In terms of dietary sources, fish and tea are considered natural sources of fluoride, as well as tap water that has been fluoridated. The extent to which the condition truly exists, and its relationship to fluoride poisoning has given rise to some controversy. Fluorine is not considered to be an essential nutrient, but the importance of fluorides for preventing tooth decay is well-recognized, although the effect is predominantly topical. Prior to 1981, the effect of fluorides was thought to be largely systemic and preeruptive, requiring ingestion. Fluoride is considered essential in the development and maintenance of teeth by the American Dental Hygienists' Association. Fluoride is also essential as it incorporates into the teeth to form and harden teeth enamels so that the teeth are more acid resistant as well as more resistant to cavity forming bacteria. Caries-inhibiting effects of fluoride were first seen in 1902 when fluoride in high concentrations was found to stain teeth and prevent tooth decay.
The high electronegativity of fluorine (4.0 for F vs. 2.5 for carbon) gives the carbon–fluorine bond a significant polarity/dipole moment. The electron density is concentrated around the fluorine, leaving the carbon relatively electron poor. This introduces ionic character to the bond through partial charges (C—F). The partial charges on the fluorine and carbon are attractive, contributing to the unusual bond strength of the carbon–fluorine bond. The bond is labeled as "the strongest in organic chemistry," because fluorine forms the strongest single bond to carbon. Carbon–fluorine bonds can have a bond dissociation energy (BDE) of up to 544 kJ/mol. The BDE (strength of the bond) is higher than other carbon–halogen and carbon–hydrogen bonds. For example, the molecule represented by CHX has a BDE of 115 kcal/mol for carbon–fluorine while values of 104.9, 83.7, 72.1, and 57.6 kcal/mol represent carbon–X bonds to hydrogen, chlorine, bromine, and iodine, respectively.
Using tap water (whether straight from the tap or filtered first) is generally considered to be better for one's environmental impact than habitually drinking bottled water, because the bottling and distribution of bottled water consumes resources and produces emissions (electricity and oil to make the bottles, diesel fuel to truck the filled bottles through the supply chain, truck exhaust, powerplant emissions, bottle recycling, and so on). In comparison, the water treatment plant activities were going to happen anyway in either case, but the other costs and effects are avoided in the tap water case.
By 1996, Zip introduced air-cooled Zip HydroTap under-bench filtered instant boiling water systems which also dispensed filtered chilled drinking water from a single touch-button electronic tap – an instant success for workplace and home kitchens in Australia and abroad. By 2004, the initial Zip HydroTap was superseded by re-designed product engineering and a distinctive lever-action electronic tap offering precise water flow control, safety, and power-saving features, plus a "font" accessory which enabled the tap to be positioned away from any sink, with independent drainage. The new Zip HydroTap proved popular worldwide. It has been improved each year. Models introduced in 2012 provide sparkling chilled and filtered drinking water (in addition to boiling and chilled) from one tap.
In summer, when water demand peaks, there are region-wide restrictions on lawn sprinkling to ensure that water supplies are adequate for more important uses, such as drinking water and fighting fires.
In 2008 Metro Vancouver launched a campaign inviting the region’s residents to make a "tap water pledge" to drink tap water in refillable bottles instead of buying single-use plastic water bottles, with the goal to reduce sales of bottled water by 20 per cent by 2010. In 2011, 85 per cent majority of residents polled in the region said they primarily drink Metro Vancouver tap water instead of buying bottled water.
The region’s waste water is treated in one of five waste water treatment plants operated by Metro Vancouver, two of which use primary treatment and the remaining three use secondary treatment.
Tap water ("running water", "city water", "town water", "municipal water", etc.) is water supplied to a tap (valve). Its uses include drinking, washing, cooking, and the flushing of toilets. Indoor tap water is distributed through "indoor plumbing", which has existed since antiquity but was available to very few people until the second half of the 19th century when it began to spread in popularity in what are now developed countries. Tap water became common in many regions during the 20th century, and is now lacking mainly among people in poverty, especially in developing countries.
Bromine pentafluoride (BrF) was first synthesised in 1930. It is produced on a large scale by direct reaction of bromine with excess fluorine at temperatures higher than 150 °C, and on a small scale by the fluorination of potassium bromide at 25 °C. It is a very vigorous fluorinating agent, although chlorine trifluoride is still more violent. Bromine pentafluoride explodes on reaction with water and fluorinates silicates at 450 °C.
Changing the water for the goldfish is one way to keep the water safe from harmful levels of nitrates and keep the tank clean. When making a water change, a third of the water should be taken out of the tank to keep the good bacteria in the tank water. Squeeze the filter sponges gently in the tank water to clean, if applicable. Using a vacuum will help clean the gravel at the bottom and remove any rotten food that has settled towards the bottom. The water should be filled with treated tap water with the same temperature as the water in the tank to ensure the water does not shock the fish. Tap water should be not used to clean the decorations, filters, and the equipment due to the tap water killing the good bacteria for the fish.
Although the use of molecular fluorine as an electrophilic fluorine source is often the cheapest and most direct method, F often forms radicals and reacts with C-H bonds without selectivity. Proton sources or Lewis acids are required to suppress radical formation, and even when these reagents are present, only certain substrates react with high selectivity. Handling toxic, gaseous F requires special apparatus and great care to avoid contact with air or water.
Shall fluorides, for the prevention of tooth decay, be added to the City water supply sufficient to bring the fluorine content of City water up to a level of one part fluorine to one million parts of water?
Most of the levels have taps in them, which pour water in to the level. The modelling of the water was quite advanced for a home computer game of its time; the water will flow to the lowest point that it can and when multiple taps are pouring water in one place, it will fill up proportionally fast. A lot of levels feature taps in all areas so the entire level will eventually flood, leaving Quiffy with no available source of air. This aspect is how the game derives its title.
In the radiopharmaceutical industry, fluorine-18 is made using either a cyclotron or linear particle accelerator to bombard a target, usually of pure or enriched [O]water with high energy protons (typically ~18 MeV protons). The fluorine produced is in the form of a water solution of [F]fluoride, which is then used in a rapid chemical synthesis of the radiopharmaceutical. The organic oxygen-18 pharmaceutical molecule is not made before the production of the radiopharmaceutical, as high energy protons destroy such molecules. Radiopharmaceuticals using fluorine must therefore be synthesized after the fluorine-18 has been produced.
The carbon–fluorine bond of the smaller molecules is formed in three principal ways: Fluorine replaces a halogen or hydrogen, or adds across a multiple bond. The direct reaction of hydrocarbons with fluorine gas can be dangerously reactive, so the temperature may need to be lowered even to −150 °C (−240 °F). "Solid fluorine carriers", compounds that can release fluorine upon heating, notably cobalt trifluoride, may be used instead, or hydrogen fluoride. After the reaction, the molecular size is not changed significantly, as the elements have very similar van der Waals radii. Direct fluorination becomes even less important when it comes to organohalogens or unsaturated compounds reactions, or when a prefluorocarbon is desired (then HF-based electrolysis is typically used). In contrast, the fluoropolymers are formed by polymerizing free radicals; other techniques used for hydrocarbon polymers do not work in that way with fluorine.
The first public water service began on October 17, 1887 in Yokohama. By the early 1900s, most major cities had water services. However, these water pipes often led to public water taps. In 1892, a survey conducted in Yokohama revealed that less than 1 in 4 households had a private water tap. 18,184 households used public water taps, while only 5,120 household used private water taps. By the 1930s, most new houses were constructed with a private water taps, but it would take another 30 years to become available in a village far from a city.
On 2 July 1698 Savery patented an early steam engine, ""A new invention for raising of water and occasioning motion to all sorts of mill work by the impellent force of fire, which will be of great use and advantage for draining mines, serving towns with water, and for the working of all sorts of mills where they have not the benefit of water nor constant winds."" He demonstrated it to the Royal Society on 14 June 1699. The patent had no illustrations or even description, but in 1702 Savery described the machine in his book "The Miner's Friend; or, An Engine to Raise Water by Fire", in which he claimed that it could pump water out of mines.
Savery's engine had no piston, and no moving parts except from the taps. It was operated by first raising steam in the boiler; the steam was then admitted to one of the first working vessels, allowing it to blow out through a downpipe into the water that was to be raised. When the system was hot and therefore full of steam the tap between the boiler and the working vessel was shut, and if necessary the outside of the vessel was cooled. This made the steam inside it condense, creating a partial vacuum, and atmospheric pressure pushed water up the downpipe until the vessel was full. At this point the tap below the vessel was closed, and the tap between it and the up-pipe opened, and more steam was admitted from the boiler. As the steam pressure built up, it forced the water from the vessel up the up-pipe to the top of the mine.
The Jaison Water Tap or Jayson Water Tap (also known as Waste Not Water Tap) is a self-closing water-saving tap invented in the early 20th century