Faucet Basics: Part 1 How Are Faucets Made?

For the money, a basic American fau­cet may be one of the best consumer values around. De­signed to last a lifetime, all but the cheapest almost certainly will, and if they don't, the manufacturer will at least replace the defective parts.

Today's fau­cets are designed to survive very harsh conditions, including thousands of on-off cycles every year and hard water mineral build-up, and still give year after year of flawless service.

If it does fail, a fau­cet is usually designed to be serviced by simply replacing the defective parts — typically a screwdriver operation — without first having to uninstall the fau­cet.

A Rose May Always Be a Rose but a Faucet Is Not Always a Faucet

There is almost no language more confusing than Plum­ber-ese.

Carpentry is several millennia old and has a very odd lingo indeed. But, that's almost to be expected from such a venerable calling.

Plumbing, however, is barely 200 years old so it should be a little less complicated. It is anything but.

One of the most confusing terms in plumbing is the name of the device that controls the flow of water.

In North America, the most common term is "fau­cet". In England and the former Commonwealth nations, except Canada, the term is "tap".

In the U.S. a "fau­cet" usually refers to a decorative plumbing device used to control the flow of water inside the house.

A "spigot" or "Bibb" is an outside fau­cet, and you probably have one or two attached to the side of your house.

It may also be known as a "hose Bibb", a "Bibbcock", a "sillcock", "garden valve", "garden hydrant", "garden fau­cet", or "hose hydrant", depending on where you live.

A mixing fau­cet is one in which hot and cold water are blended together inside the fau­cet. Virtually all sink, tub, and shower fau­cets are mixing fau­cets.

Non-mixing fau­cets are not usually found inside the house. But outside, the hose Bibb is a non-mixing fau­cet. Unless you have done something strange to the plumbing, an outside spigot delivers only cold water.

Not a Faucet

Shut-off “valve”, one of the valves inside your house that is not a fau­cet.

Mixing fau­cets may have one or two handles.

In a two-handle fau­cet, one handle controls the volume of cold water, and a separate handle controls the volume of hot water. Temperature is regulated by adjusting the amounts of hot and cold water entering the spout.

Also Not a Faucet

Brass Globe Valve, another of the valves inside your house that is not a fau­cet.

Single-handle fau­cets control the mix of hot and cold water and the volume of water. Water volume is independent of water temperature.

The flow of water can be changed without changing the water temperature, and the temperature can be regulated without altering the volume of water flow.

Modern finishes are unlikely to flake or tarnish. Faucet plating and coating processes, including — a process that is almost science fiction — can imitate anything: brass, nickel, pewter, even silver and gold. Epoxy coatings can keep that new finish looking new for a long time, with proper care.

Faucet valves rarely leak these days. Ceramic cartridge technologies have almost entirely banished the midnight drip, drip, drip.

But, some of the best fau­cets still use older, tried and true, technologies that are proven to work well. These may require periodic maintenance, not an onerous or difficult task.

For the old house purists, these older technologies are often the favored technologies. But, for the rest of us, the newer al­most-no-maint­en­ance ceramic technology is a better choice.

Unfortunately, the classic American fau­cet is increasingly not made in Amer­i­ca.

Some manufacturers have maintained substantial domestic manufacturing but many fau­cets are now made elsewhere — from China to the Balkans — and merely distributed by Amer­i­can companies under their own brands.

As with anything, some fau­cets are better than others, and price, while generally reflective of quality, is no absolute guarantee. You do not necessarily get a better fau­cet for more money.

All of the major fau­cet manufacturers, make mid-priced fau­cets that are lifetime or near-lifetime products.

When you pay more than mid-price then you are generally buying the cachet of high-style or custom hand finishing or both.

These are usually excellent fau­cets but not necessarily a quantum leap better than major-brand mid-priced fau­cets.

They are produced in smaller runs or even made one at a time as they are ordered, so they do not have the cost savings of large production quantities. Thus the higher price. But, even these are often sharply discounted.

Faucet Materials

Any material that will hold water can be used to make a fau­cet.

Faucets have been created from wood, glass, bamboo, or ceramics. These materials are not in common use but they are available.

More typically, fau­cets are made from metals: brass, bronze, copper, pewter, stainless steel, and zinc alloys. Pewter and bronze are rare, found only in custom fau­cets.
From the top: Glass fau­cet designed by Phillipe Starck for wood and brass fau­cet from Omax Rubinetteria of Italy, and the brass and ceramic Vas fau­cet (now discontinued). As far as we know the Starck faucet has never actually be manufactured.

Faucets can also be made of plastic.


The traditional material for fau­cets is brass.

Brass is prized for fau­cets because

  • It resists corrosion. It will not rust through like iron or steel.
  • It has a relatively low melting point — making it easy to cast.
  • It is soft enough to machine with little effort yet hardy enough to endure the rigors of life as a fau­cet.
  • It takes finishes such as chrome plating very well.
  • It is easily recycled. About 80% of the brass used in new fau­cets was previously used to make something else.
  • It is anti-microbial.

Brass is an alloy of copper and zinc. There are over sixty compositions of brass. Copper content ranges from 58% to 90%. Common yellow or "alpha" brass is about 60% copper and 30% zinc.

The copper in brass is anti-microbial — it kills germs, a fact that has been known since the rise of the Pharaohs, but how it does so has only recently been uncovered.[1]

Most fungi (mold and mildew) and most bacteria cannot survive in contact with brass. In tests on colonies of E. Coli bacteria conducted by the EPA, 99.9% of the colony was killed after two hours of exposure to brass.

Small amounts of other materials may be added to give the brass specific properties.

Antimony or tin retard a form of corrosion known as dezincification which can weaken brass over time.

Manganese makes brass harder and nickel refines the grain structure improving strength.

Aluminum makes the brass stronger and more corrosion-resistant. Admiralty and Naval brasses used in salt-rich maritime environments contain a relatively high proportion of aluminum.

Lead is used to make brass more malleable, less brittle, and easier to form and shape.

In fau­cets, however, lead is dangerous to human health, and especially dangerous to children because it can leach into the drinking water that passes through the fau­cet.

According to the En­vir­on­ment­al Prot­ec­tion Agen­cy (EPA), lead can cause slowed growth, learning problems, hearing loss, anemia, hyperactivity, and behavior issues.

Before 2014, brass in a fau­cet could contain as much as 8% lead and still call itself lead-free. Now the maximum lead content in a fau­cet is 0.25% (1/4 of 1%), basically just a bare trace of lead.

To ensure the absence of lead in the brass inside a fau­cet that is in contact with the water passing through the fau­cet, the fau­cet must be tested in a laboratory and certified lead-free. If it is not certified, it cannot be legally installed in a drinking water system.

Keeping Faucets Safe To find out more about how fau­cets are testeed and certified for safety, see Keeping Faucets Safe & Reliable

To comply with the new restrictions on lead, today's fau­cet brass uses other additives to ensure malleability. The most common substitute materials are bismuth and silicon.

Bismuth is similar to lead – right next to lead on the periodic table of elements – but it is not harmful to humans. Bismuth, however, is expensive. It is 300 times rarer than lead, even rarer than silver, which is the reason that bismuth-brass alloys are considerably more expensive than leaded brass.

Bismuth has several other problems. It is, unlike lead, a brittle metal, and requires a more precise casting process to preserve the of brass. The result of improper casting is illustrated by a 2012 recall by the Consumer Product Safety Commission of 63,000 azimuth-brass ball valves made in China for use in natural gas pipelines. They were much too brittle resulting in cracks and dangerous valve failures.

Bismuth is also an environmental issue. Brass alloyed with bismuth cannot be easily recycled with non-bismuth brass and must be kept separate to avoid cross-contamination of the materials.

Silicon has somewhat similar recycling issues, but not as severe. Some alloys can be recycled with ordinary brass. Its chief advantage is that it is plentiful. It is not, however, less expensive.

Silicon-brass is considered a high-strength brass. The silicon increases resistance to wear and corrosion. Its disadvantages are that it requires a higher casting temperature than ordinary brass and its hardness makes it much more difficult to machine.

Plumbers don't care for it because it requires a hotter torch and special techniques to solder without which "cold" solder joints may spring a leak.

Nonetheless, it is increasingly popular among fau­cet manufacturers. One alloy, Eco-brass (C69300), is especially formulated for plumbing fixtures.

Stainless Steel

The other common metal material for fau­cets is stainless steel.

Stainless Steel Faucet

Photo: Moen, Inc.

Stainless steel is popular in kitchen fau­cets to exactly match stainless steel kitchen sinks. This is the Notch contemporary kitchen fau­cet.

Steel is harder than brass and has a higher melting point, making it more difficult than brass to cast and machine.

But, it contains no lead, which in today's regulatory environment is a big plus. And, because it is stronger, castings can be thinner, saving on material.

The stainless steel used in fau­cets, 304 or 316 stainless contains 18% chrom­ium and 8-10% nickel.

The nickel gives the steel a particular crystalline structure which increases its strength and malleability. Chromium (or chrome) helps the steel resist corrosion. A small amount of molyb­denum (2-3%) is added to 316 steel to better resist acids.

Both alloys are austenitic steels, meaning they are low- or non-magnetic.

Stainless 304, known as "food grade" stainless, is by far the more commonly-used alloy for making fau­cets. However, 316 stainless, known as "marine grade," has superior resistance to pitting, corrosion, and staining, particularly in acidic or salt environments.

For kitchen fau­cets, 316 is considered the better material, but it is more expensive. Only a few manufacturers use it in their fau­cets.

switched from 304 to 316 stainless in 2019. sells stainless kitchen fau­cets made in Italy by Super Inox S.R.L. These faucets are also 316 stainless.

To make things a little more confusing, there are actually two commonly used grades of 304 stainless. The more widespread is 18/8, representing the proportion of chromium and nickel in the alloy: 18% chromium and 8% nickel.

Stainless steel fau­cets are usually made from 18/8 stainless but some are made from 18/10 stainless, a slightly better grade containing 10% nickel. It is commonly used to make knives, fine cookware, flatware, and restaurant-quality sinks. The added nickel makes the alloy a little harder, able to take a higher polish and, for knives, a sharper edge.

Zinc Alloy Faucet Handles

Zinc is easily identified by its dull gray color. Zinc fau­cet handles shown before (top) and after chrome plating.

There is virtually no stress on a fau­cet handle, so zinc works well in this fau­cet component. But, zinc is suspect in any part of a fau­cet that must endure water pressure year after year without failing.

Some fau­cets, made primarily in Asia, contain a lower quality stainless. As a buyer, you should always look for a certification that the steel used in the fau­cet is 304 (18/8 or 18/10) or 316 steel. Just the word "stainless" is not enough.

Fau­cets can be made from a zinc alloy. The best known is an alloy called ZAMAC (for its metal content: Zinc, Aluminum, Magnesium, And Copper) or ZAMAK developed by the New Jersey Zinc Company in 1929.

The original use of this "pot metal" was to replace more-expensive brass in applications where the strength of brass was not needed but its corrosion-resistant properties were.

It is commonly used in the manufacture of die-cast objects such as children's toys, model trains, locks, cabinet pulls and knobs, zippers, plumbing fixtures, including fau­cets, and, as its nickname suggests, cooking pots.

It is a distinctive metal, dull and gray but can be plated with chrome or another finish metal to make it indistinguishable from a brass fau­cet.

In the past the material's principal use was the manufacture of economy faucets, but with the advent of severe lead restrictons in brass and the soaring cost of lead-free brass, its use has expanded.

Most fau­cets that are made of zinc will say so on the box, sometimes indirectly.

The phrase "All-Metal" on the box tells you that parts of the fau­cet contain at least some zinc. If it's all brass, the box will say "All Brass".

However, some companies can get crafty with their terminology. For example

  • "All Brass Body" usually means that handles and other ancillary parts are zinc or even plastic.
  • "Brass construction" almost always means some of the parts are zinc, as opposed to "All brass construction".
  • "All brass fau­cet" is another iffy phrase. It sometimes means that the fau­cet is all brass but it may also mean that the fau­cet body and spout are brass, but other parts are not.

We have found that the best way to check for zinc is to get a peek inside the fau­cet. This may require one guy to wield a screwdriver and another to distract the store clerk.

Removing the handle for a quick look inside the casting where it joins the stem often tells the tale. If it's gray metal, the casting is zinc, if it's "coppery", it's brass.

A glance up the spout may also help reveal the fau­cet's composition, and does not require any disassembly. A penlight is helpful here. A dull gray spout is zinc. If it's brown, green, or "brassy", then it's brass.

Zinc and its alloys are not all bad, however.

In the body of a fau­cet or its spout — any part subject to water pressure year after year, zinc and zinc alloys are highly suspect.

But, ancillary parts such as handles, base and wall plates, and other trim pieces can be made of a zinc alloy without compromising the quality of a fau­cet. These parts do not need the strength of brass and zinc can be used to save the cost of the more expensive brass, shaving a few dollars off the retail price of the fau­cet.

Likewise, in core and shell faucet construction (see more about this new form of faucet building below), what was once the body and spout of the faucet is just a non-structural decorative shell that is not under pressure. Zinc is increasingly being used in shell manufacturing. It takes finish as well as brass and sometimes better, and, according to its adherents, can be more precisely cast and forged.

Companies using core and shell technology like have now converted most of their shells to a zinc alloy.


Plastic fau­cets have specialized uses. Examples are in laboratories and very saline coastal environments where corrosive chemicals or salt-laden air might damage a metal fau­cet.

They are also common in RVs. In this environment, plastic fau­cets can last a long time. RV fau­cets are fed from an overhead tank and are not subject to much water pressure. Plus, they are used only a few weeks or months out of a year.

But, for sustained residential use in a bathroom or kitchen under household water pressure, a plastic fau­cet is not a good choice.

Typical static household water pressure is between 40 and 60 pounds per square inch (psi). (Most experts suggest that 50 psi is the most comfortable pressure, and if your water pressure is regularly over 50 psi, you might consider installing a pressure regulator.)

Under certain circumstances, however, such as shutting a fau­cet suddenly, water pressure can surge to well over a whopping 200 psi.

Plastic fau­cets simply cannot handle that sort of abuse year after year.

In addition, there are the problems caused by dissolved minerals.

Household water contains dissolved minerals. Among these are magnesium, limestone, iron, silica, and even granite. The types and quantity of minerals vary depending on where you live. But, if you have "hard water", then your water contains lots of minerals.

When water flows through your fau­cet some of these minerals are left behind as very hard, rock-like, deposits.

In your bathtub or sink these are known as "limescale" or "mineral deposits" and they are the very devil to get rid of after they have built up for a while and etched into the fixture material.

They behave the same way inside your fau­cet where you can't get at them or even see them. They grind away at the internal moving parts of your fau­cet, wearing them down over time. Brass and steel can handle the abuse for years and years without failing, plastic cannot.

However, In parts of a fau­cet not under pressure and not subject to mineral buildup, plastic, like zinc, has a place, (although zinc alloys are a better choice). It can replace expensive brass in baseplates, handles, and other components that are not pressurized,

Plastic has also become almost universal in and housings for some cartridge valves. In these applications, they have worked very well, which is a little surprising. One of the tests that cartridges must survive in order to be certified is a surge test in which the plastic cartridge must survive a pressure surge of a whopping 500 psi for one minute without deforming. (But, see Anatomy of a Failed Cartridge, below).

Unfortunately, however, plastics have also become common in the spray heads ("wands" in the fau­cet-speak) of kitchen fau­cets

Manufacturers began switching from metal to plastic wands a few years ago for three reasons:

  • Plastic does not get uncomfortably hot in use like metal wands;
  • Plastic is not as heavy and is more comfortable to hold for a long period of time; and
  • Plastic is much, much cheaper than stainless or brass.

It is also true, however, that plastic fails more often than metal wands. But, it has now become almost unavoidable.

Even upscale fau­cet companies like have shifted to plastic wands. While the wands have gotten better, they are not yet on par with metal wands when it comes to longevity.

The sure cure for a wand that is too hot to hold is to dial down the water temperature. There is nothing in the kitchen that actually needs to be rinsed in scalding water.

If you have a choice – and often you will not have a choice if you are to get the look, features, and price you prefer – opt for a metal wand.

There is one form of plastic that does work and works well in fau­cets. It is cross-linked polyethylene, commonly known as PEX.

PEX has been used with good results to replace copper water pipes for over 30 years. It is recognized by all national plumbing codes as a suitable material for water channels. It is, in many ways, better than copper because it is a lot less expensive, easier to install, and is much less likely to burst from freezing.

It has only very recently begun to be used in fau­cets, largely in response to the very low lead requirements of the Safe Drinking Water Act effective in January 2014.

The Manufacturing Process

Three basic steps are required to manufacture a fau­cet: forming, refining, and finishing.

Finishing is treated in detail in part 5 of this series: Faucet Finishes. Here we will be looking at the first two steps: forming and refining.


Since almost all faucets a made from metal, forming a faucet is a process of shaping metal into a rudimentary faucet. In most faucet factories the process is highly automated. Machines controlled by computers do most of the work.

The processes most often used to form faucets are casting and forging.


Casting involves pouring molten metal into a mold or die in the shape of the faucet part to be formed, then allowing it to cool and harden.

Casting had its advantages and drawbacks.

Advantages include the ability to create intricate detail not available from other forming methods. Disadvantages include potential defects in the casting that can result in eventual failure. The most common of these are voids and cracks that can weaken the casting. These are often invisible to the naked eye but can be detected through ultrasonic testing.

Sand Casting

The earliest process for casting metal used sand molds. They are still commonly used for small runs even in production facilities.

Once an object to be used as the "pattern" for the casting is selected (or created, often out of wood), a special fine-grained sand called "greensand" is poured into a box called a "flask." The sand is alightly moistened so it will adhere.

The flask is made in two parts. The bottom half, called a "drag", is first filled with sand and tamped. The pattern is then embedded in the sand.

The top part of the flask called a "cope" is also packed with sand to complete the mold. It is attached to the drag. The two halves of the mold are separated and the pattern removed leaving a void in the sand in the shape of the part to be cast.

By reassembling the mold and then filling the void with molten metal through a channel (or "sprue") made in the sand the pattern is precisely duplicated in metal. (To see a sand mold being made, watch this video.)

The disadvantage of sand casting is that it is relatively slow. The mold is destroyed in the casting process and has to be made over and over again for each casting. It produces a fairly rough, granular surface (See the image below) that requires considerable refinement after casting to produce the finished object.

However, sand casting has the advantage of being scalable. It can be used to make a single casting or stepped up for small production runs of a few hundred pieces.

Many manufacturers of high-end faucets made as ordered in ones and twos or in relatively small batches prefer sand casting. It does not require a major investment in expensive metal dies that can cost thousands of dollars each.

Die Casting

Most production casting is what is called die casting. It uses metal molds or dies made from a steel especially formulated to be very hard and resistant to wear. These can cast many thousands of faucets before they wear out and need to be replaced.

Dies are made in two halves that are clamped together to make the casting. Where the halves meet is called the parting line.

The die-casting process used by most manufacturers is called cold-chamber casting. In contrast to hot-chamber casting, the casting metal is melted outside of the machine.

In the much faster hot-chamber casting, the metal is melted inside the machine, but hot-chamber casting is not possible with metals having a high melting point like the brass and zinc alloys used to make faucets.

To make the casting, a precisely measured amount or "shot" of the molten metal is fed into an ejection chamber. The shot is then driven into the die by a piston, allowed to cool, then the dies are separated to retrieve the casting.


A second common process for making faucet parts is forging, a method of forming in which solid metal is forced into a die under extreme pressure.

Forging is perhaps the oldest process known to man for shaping metal into useful objects.

Long before mankind learned to make fire hot enough to melt metal, smiths werd forging metal with hammer and anvil. Power hammers are still used in forging, primarily for shaping steel. Hydraulic presses are more common for forging the relatively softer metals used to make faucets.

In die forging, a slug of metal is pressed into a die that has the shape of the item to be forged. To facilitate the process, the metal is often heated to what is called its forging temperature. Heating softens the metal so it more easily conforms to the shape of the die.

Often a metal's forging temperature is just a few degrees lower than its melting point. Most alloys of brass, for example, soften at around 1,500°F (815°C) and melt at 1,710°F (930°c).

Nevertheless, because metal does not need to be melted and then cooled, forging is faster than casting. It also tends to strengthen the forged part by aligning the grain of the metal to follow the shape of the forging.

Its disadvantage is that forged parts are often made in two pieces and then joined by soldering, brazing, or welding. The joint is usually weaker than the forging itself and more likely to fail under water pressure.

Click to watch a video of faucet parts being forged on a forging press.

Monoblock Forming

Some faucets are neither cast nor forged. They are machined out of a solid block of raw metal. These are called monoblock faucets.

These tend to be very plain contemporary designs simply because elaborate designs are difficult to create using the process. Channels inside the faucet are borings rather than being created by casting or forging.

Monoblock faucets are considered by many to be the most structural sound of all faucets because there are no seams.


A newly formed faucet is usually far from ready for the finishing process. It needs to be refined.

Trimming, Grinding, and Polishing

Much of refinement is merely a process of cleaning up a rough casting.

When it emerges from the casting process, a faucet part is attached to a sprue, extra metal that formed in the channel used to deliver the metal to the mold.

There may also be flanges of metal where it oozed out of the parting line where two halves of the mold came together.

All of this has to be trimmed away.

Then the rough surface of the casting has to be ground and polished to get it ready for finishing. In small shops, this may be done by hand. But, in most production facilities it is done by a robot.

To watch a robot grind and polish a faucet through the many steps required, view this video.


Many parts of a faucet require threaded openings and precise mating surfaces. Providing these features is the province of machining or milling.

In former years, machining was done by skilled machinists who might apprentice for many years before they were considered accomplished enough to be trusted with this critical task.

In some small shops, a machinist may still do this work. But, in production facilities, it is all done by computer-controlled machinery.

Core and Shell Construction

The need to eliminate lead in faucets has produced a mini-revolution in how faucets are made.

In conventional fau­cet construction, function and decoration are combined. The body and spout of the fau­cet do double duty. They give the fau­cet its appearance. But, they also provide the channels through which water flows.

With core and shell construction, the channels that carry water (the core) are separate from the body of the fau­cet (the shell).

The two major U.S. faucet companies, have both adopted core and shell.

In Moen's fau­cets, water is routed through copper tubing inside the faucet. Delta uses PEX tubing. This tubing, not the faucet itself, channels water and contains the water pressure.

The body of the fau­cet becomes just decorative trim that hides the core from view. Since water never touches the shell, it cannot possibly pick up any lead.

Core and shell design helps keeps the cost of lead-free faucets under control. It also has several advantages over conventional faucet construction.

  • The decorative outer shell does not need to be very strong. It is not structural and plays no role in containing water pressure. It can be made of relatively thin-walled metal, thus saving on material and fabrication costs.
  • The shell does not need to be lead-free. Water never touches it, so it can be made of much less expensive leaded brass or a zinc/aluminum alloy.
  • It separates function from appearance, making design more flexible.
  • In conventional faucet construction, the design of the faucet can affect how well the faucet works. Designers have to be constantly aware of how a design might impede the operation of the faucet.
  • With shell technology, the function of the faucet is entirely contained within the internal mechanism. The design of the exterior shell has nothing to do with the operation of the faucet, so designers are free to concentrate on how it looks rather than how it works.
  • Shell construction creates an air gap between the inner waterway and the outer shell of the fau­cet, virtually eliminating heat transfer to the shell so it does not get uncomfortably hot in use.

Faucet Valves and Cartridges

From the point of view of the mechanics involved, a basic fau­cet is nothing more than a valve that controls and directs the flow of water through a tube. The main components are the valve itself, a body to contain the valve, a handle to operate the valve, and a channel through which the water flows. … (Continues)

Rev. 01/05/23