This is PM's sixth annual installment of our popular "History of Plumbing" edition. In the previous five years we have highlighted numerous developments in plumbing technology throughout antiquity. This year we decided to take a peek at the more recent past to view the roots of modern plumbing.

The nature of plumbing is such that its most clever innovations usually are obscure to the public eye. People take for granted devices such as the T&P valve, kitchen disposal, flush toilet and so many of our industry's other useful gadgets that have made their lives safer, healthier, more comfortable and convenient. Even plumbers who work with these mechanisms every day tend to lose sight of the ingenuity that went into them.

By spotlighting these great inventions, we hope to instill a greater appreciation for the creativity of our industry's forefathers. Because of space limitations, for this first installment we limited our coverage to the first half of this century. We also wanted to focus on breakthroughs that have withstood the test of time. In future editions of "History of Plumbing," we plan to look at more modern innovations as well.

In compiling this series we tapped the engineering departments and archives of major plumbing manufacturers for guidance. We thank them for their cooperation.

Innovations At Kohler Co.

1911: Kohler Co. introduced the industry's first one-piece recess bath with an integral apron. Before this time, built-in baths were cast in two separate sections - the tub proper and the apron. The apron and the tub were then either fitted together by the plumber when the tub was installed, or the two pieces were welded together at the factory before the fixture was enameled. The new one-piece tub, void of crevices, joins and seams, was much more sanitary and attractive than the two-piece forerunner.

1926: One of the most advanced products to come out of the 1920s was the Kohler electric sink. It was a combination of a conventional kitchen sink and the electric dishwasher almost as we know it today. The sink was an enameled iron fixture, massive and expensive, half sink and half dishwasher. Invented by Kohler employee Frank Brotz, its only drawback was that it was a generation or two ahead of its time.

1927: Kohler's introduction of bathroom sets (bathtub, toilet and lavatory) in matching colors made fixtures much more than functional. Now instead of stark and sterile white, consumers could choose spring green, lavender, autumn brown, old ivory or horizon blue. For the first time, there was a concern for the aesthetics when planning a bath. However, beyond aesthetic considerations, the color concept was a revolutionary technological achievement in the plumbing industry of the time. The manufacturing of enameled cast iron fixtures and vitreous china fixtures required vastly different raw materials, processes and techniques, so matching color was difficult.

Moen's Single-Handle Mixing Faucet

Few people are as synonymous with inventions and innovations as Al Moen. He holds more than 75 patents, but his most revolutionary is the one issued in 1942 for the single-handle mixing faucet he invented in 1937.

As the cliché says, Moen's invention rose from necessity. While an engineering student at the University of Washington, Moen worked evenings in a garage to pay his tuition. One day he burned his hands while washing them, using a conventional two-handle faucet. From that experience, he resolved to create a faucet that would give the user water at the desired temperature. His first design was for a double-valve faucet with a cam to control the two valves. Moen showed his designs to a major fixture manufacturer, who showed him why the double-valve was the wrong approach. He then went to a cylindrical design with a piston action. Between 1940 and 1945 he designed several faucets, finally selling the first single-handle mixing faucet in San Francisco in late 1947. Since then, single-handle faucets have become so popular that today they can be found in over 40 percent of American homes.

However, Moen's contributions don't stop with the faucet. His innovative mind also produced the replaceable cartridge, a push-button diverter, back-to-back installation and the swivel spray. For all his achievements, Moen's been nominated for the Inventers Hall of Fame sponsored by the U.S. Patent Office.

Sloan Valve Co.'s Flush Valve

William E. Sloan applied for a patent on his Royal Flush Valve June 13, 1906, and on Dec. 6, 1910, he was issued Patent Number 977,562. With a flush valve installation, water flows under pressure from the supply piping directly to the fixture. Because of this connection to the water supply, they stand ready for repeated operations. Also, because the water passes through the flush valve under pressure, the fixture is flushed with a scouring action to ensure proper cleansing. These two features, among others, are responsible for the popularity of flush valves in commercial buildings.

The first flush valves produced by the Sloan Co. were designed for manual operation. Today the state of the art is for flush valves to be sensor-operated to make flushing automatic.

Through the 85 years that the Sloan Valve Co. has manufactured the Royal Flush Valve, about 120 different companies have been in the same business at one time or another. Today only a few remain.

In-Sink-Erator's Disposer

Wisconsin architect John Hammes invented the food waste disposer in 1927. In his original model, the disposer ground up the food waste so it could be flushed down the kitchen drain. Hammes tinkered with his original model for 10 years before he launched the In-Sink-Erator Mfg. Co. and its line of disposers.

When disposers were first introduced, most municipalities banned them because of worries about their impact on sewage treatment systems. However, by 1960 they were required in new construction by ordinance in more than 100 communities because of their sanitary value. Much like the water closet, a disposer immediately removes raw food waste from the home through sewerage pipes to treatment plants, where it can be treated and neutralized.

After more than 40 years on the market, disposers are now found in more than 50 percent of all households. About 4 million disposers are sold annually.

Halsey Taylor's Double Bubbler

In 1896, Halsey W. Taylor lost his father to typhoid fever caused by a contaminated water supply. This personal tragedy led the young Taylor to dedicate his life to providing a safe, sanitary drink of water in public places. His quest led to the invention of the Double BubblerT, which projects two separate streams of water that converge to provide a fuller and more satisfying drink. The Double Bubbler also ensures that people drink far away from the actual projector.

Taylor founded the company that bears his name in 1912. He developed his two-stream Mound building projector, as it was called then, for the U. S. government during World War I. Soon after, in 1926, he perfected and patented what is now known as the Double Bubbler.

Brass-Craft's Flexible Plumbing

Robert Zell created flexible plumbing supplies from brass bar stock and copper tubing in the basement of home in Royal Oak, Mich., in 1939. However, because of wartime material shortages, the product wasn't in production until the Brass-Craft Mfg. Co. was founded in 1945.

Zell's flexible supplies were on the leading edge of the industry's transition from rigid galvanized iron pipe to flexible copper plumbing. These supply lines connected stub-out plumbing from the wall to plumbing fixtures such as faucets and toilets. Flexible copper supplies made it possible for the plumber to design an easily-installed supply stop beneath a sink and toilet. Before this, most homeowners had to turn off all the water to the house to service one leaking faucet.

Delta's Single-Handle Ball Valve

In designing the first ball valve in 1945, Landis H. Perry had a specific objective: "To provide a combined volume and blending control valve having relatively simple and yet effective means for sealing the valve element." Beyond that, Perry also sought to create a design that could be repaired with "a minimum of difficulty."

A patent was issued for Perry's ball valve in 1952. Shortly thereafter, Alex Manoogian purchased the rights to the patent and introduced the first Delta faucet in 1954. Manoogian, the founder of the plumbing industry giant Masco Corp., immigrated to the United States in 1920 to escape the genocide of the Armenian Christian minority by Moslem Turkey. His driving ambition was to make enough money to send for his family who had fled to Greece in 1922 to escape the mounting pogroms.

The Delta single-handle faucet was the first to use a ball-valve design and it proved very successful. By 1958, just four years after the product was unveiled, Delta's sales topped $1 million.

Haws' Drinking Faucet

Luther Haws was a self-employed plumber and sheet metal contractor in the early days of the 20th century. To those occupations, he added the job of sanitary inspector for the city of Berkeley, Calif. It was his role as an inspector that led to his invention of the first drinking fountain. In 1905, while on his rounds at a public school, Haws noticed the children drinking water out of a common tin cup that was chained to the faucet.

He knew this wasn't a sanitary situation, so when he returned to his plumbing shop he fiddled with some spare parts. Using available plumbing parts - the ball from a brass bedstead and a self-closing rabbit ear valve - Haws assembled the first drinking faucet. He showed his new invention to the Berkeley school department, which installed some of the first models.

Haws eventually gave up the plumbing company and formed the Haws Sanitary Drinking Faucet Co. in Berkeley in 1909. He received a patent on his product in 1911.

Watts' Automatic T&P Valve

Watts Regulator Co. introduced the first automatic temperature and pressure relief valve in the late 1930s. The new valve opened and closed automatically on both pressure and temperature.

Previously, two forms of protection were used. One was the pressure-only relief valve that didn't control temperature, which was the cause of water heater explosions. The second was a fusible plug-type temperature and pressure relief valve. When the water temperature reached 210 degrees F, the lead plug melted. This created a discharge port and the overheated water flowed to atmosphere. The water continued to discharge until manually shut off.

Watt's discovery of the T&P valve has nearly eliminated water heater explosions and ensured that these appliances are safe for home use.

Eljer's Vitreous China Water Cistern

Invented by one of the original founders of Eljer in 1903, the vitreous china water closet cistern replaced the wall-hung wooden or copper-lined wooden cisterns used to flush a water closet. The vitreous china model received a great deal of resistance from the trade and the public. The strength of the product was doubted so acceptance was slow. To prove just how sturdy china really was, Eljer hosted a demonstration. The cistern was laid on its back on a steel rail, a plank was placed on top of it and 27 men stood on it.

The round cistern was used by Eljer for approximately seven years. In 1908 the company introduced the first rectangular cistern that was cast in a mold - the method used in the plumbing industry today.

Symmons' Pressure-Balancing Shower Valve

Working with his own hand-made wood patterns in a vacant piano factory in Boston in 1939, Paul C. Symmons invented the first pressure-balancing shower valve and founded the company that bears his name.

Symmons discovered that sudden temperature changes in the shower were caused by pressure changes in the supply lines. Shower water got suddenly hot when someone somewhere else in the building turned on a cold water faucet or flushed a toilet. Conversely, turning on the hot water faucet caused the shower water to turn cold.

Symmons perfected a valve that uses a hydraulic piston as the prime control units. As soon as the valve is turned on, both hot and cold water exert pressure on opposite ends of the piston, balancing it in the valve. If the hot water pressure drops, the piston reacts and reduces the cold inlet opening. The piston continually equalizes the pressure of hot and cold water, even when supply pressures change suddenly or drastically.

Milwaukee Electric Tool's Sawzall

Invented by METCO engineer Ed Ristow, the first Sawzall was sold in 1949, nine years before a patent was finally granted. Ristow's Sawzall incorporated a reciprocating mechanism with only three moving parts that was designed to provide a 3/4-inch stroke at 2,250 strokes per minute.

At the time, the only similar tools on the market were drills with reciprocating attachments. They were heavy and required two hands to operate. The Sawzall weighed only 6.74 pounds and, with the right blade, could efficiently rough-out any shape in wood, plaster, metal or plastic.

Whitlam's Ready-Made Pipe Thread Sealant

J. C. Whitlam II was the first to formulate and market a ready-to-use thread sealant in 1900. While working for a paint manufacturer in the late 1890s, Whitlam watched plumbers buy red or white lead pigments and linseed oil to mix together and use as a paste thread sealant. Whitlam began experimenting in his kitchen on a nonpoisonous, ready-made product. By 1900 he had perfected a gray paste he called Tyte-Unyte that did the job better, at less cost and was safe to use. Whitlam set up a small manufacturing facility in Cleveland, but demand soon exceeded his production capabilities. In 1912 he moved to Wadsworth, Ohio, and built a factory to market Tyte-Unyte throughout the world.

ITT's Hydronic Technology

In 1905 Hoffman Specialty designed and patented the float and thermostatic-type automatic steam vent for one-pipe steam heating systems. Prior to this invention, vents were mostly bi-metal, which allowed some condensate to drain through the vent. The principle of the float and thermostatic vent for one-pipe steam systems is used by nearly all manufacturers today.

In the mid to late 1920s, McDonnell & Miller manufactured automatic boiler waterfeeders to combat the high number of boilers being damaged by dry firing, which is caused by a lack of water. In the early 1930s, McDonnell & Miller was granted a 17-year patent on its development of a cool-water feed valve.