5 Main Types of Plumbing Pipes Used in Homes

Whether hiring a plumber or taking on a do-it-yourself plumbing project, the experience can be confusing because of the choice of several types of plumbing pipes. Eventually, pipes’ uses tend to blend together. Which type of pipe should be used for water supply, drainage, sewer, and even for the exterior? The answer is not as clear as it may have been in the past when the main pipes of choice were galvanized steel or cast-iron.

PEX Pipe

PEX, or cross-linked polyethylene, pipe is one of the newest and most popular pipes to hit the plumbing market. PEX is used only to supply water. PEX is a pipe that is rigid enough to withstand the pressures of water supply but flexible enough to weave throughout walls, ceilings, basements, and crawlspaces. PEX has truly delivered water-supply plumbing into the hands of do-it-yourselfers and professional plumbers.

Pros

Color-coded red for hot water and blue for cold water

Highly flexible, with 90-degree curves possible

Attaches with push-fit plumbing fittings, among other types

Inexpensive

Able to join with copper pipe

Cuts easily

Cons

Long-term capabilities untested

May leak with push-fit plumbing fittings

Cannot be recycled

PVC Pipe

PVC, or polyvinyl chloride, pipe is a drain or vent line type of plumbing pipe. PVC initially gained popularity because it was lighter and easier to work with than traditional galvanized steel pipe. PVC pipe is moderately easy to install and requires little more than a hacksaw and a miter box to cut. PVC glues together with solvents.

Pros

Diameters clearly marked on the white surface of the pipe

Inexpensive and can be used for long runs such as for irrigation

Easier to work with than steel or copper

Cons

The pipe cannot be unjoined and must be cut

Glued pipes can be prone to leaking

Degrades in sunlight

Rigid Copper Pipe

Rigid copper is often used for water supply lines within the home. Rigid copper is easily cut with a hacksaw or with a special copper tube cutter. The connection is a different matter, as it requires a practiced hand to solder copper pipe together. Rigid copper pipe is great for water supply because it does not come with any health risks.

Pros

Though it is called rigid, this pipe can be slightly bent

Handles heat well

Stands up against intense pressures

Easy to recycle and waste copper pipe even has monetary value

Cons

Difficult for do-it-yourselfers to work with due to soldered connections

Expensive

Develops pinhole leaks

Inside of pipe may eventually corrode and impede water flow

ABS Pipe

ABS (acrylonitrile butadiene styrene) pipe is mainly used as a vent and drain line. ABS pipe looks very much like PVC pipe, except that it is black and slightly softer.

Pros

Stronger than PVC pipes

Good for underground exterior use

Works well in cold temperatures

Cons

Often not permitted by building code

Warps and deforms at certain temperatures

Flexible Copper Pipe

Flexible copper pipe or tubing is used for final runs to water heaters, refrigerators, and some sinks. Flexible copper is used only for short runs and can be cut with ease with a hacksaw. It can be bent to fit around corners.

Pros

Fits in tight, unusually shaped areas

High heat tolerance

Cons

Expensive

Thin and prone to breaking

Galvanized Steel Pipe and Cast Iron

Two additional types of pipe are sometimes found in older homes and are infrequently installed, especially by do-it-yourselfers: steel and cast iron pipe.

Galvanized steel pipe was used for decades for drainage, water supply, gas supply, and any number of other purposes. While galvanized steel pipe is still around (particularly for gas supply) it is far less used and is never used for water supply in new construction or remodel projects. Each end of the pipe is threaded, and individual pipes are screwed into each other with connecting joints.

Cast iron pipe was often used for sewer and other drainage purposes. Cast iron pipe is still found in many homes. Cast iron pipe is viable until the point that it rusts completely through. Cast iron is very heavy and difficult to cut. Retrofits tend to replace cast iron pipe with rigid plastic pipes such as ABS.

Pros

Galvanized steel pipe has the advantage of being extremely strong.

Cons

Galvanized steel pipe eventually corrodes and blocks water flow.

Some galvanized steel pipe may pass lead into the water supply.

https://www.thespruce.com/basic-types-of-plumbing-pipes-1822487

Types of Plumbing and Pipe Fittings

Types of Pipe Fittings

Adaptor

Barb

Coupling

Cross

Double Tapped Bushing

Elbow

Mechanical Sleeve

Nipple

Plug and Cap

Reducer

Tee

Union

Valve

Wye

Adaptor

Adaptors connect pipes that are not the same type. Because an adaptor can be male or female on one end, it can turn a pipe male or female.

If ends are non-threaded, they are left to be welded, soldered or glued to the pipe. Adaptors are used for PVC and copper piping.

Barb

A barb connects hoses to pipes. It is usually male at one end. The other has a barbed tube, which is a ridged and tapered cone.

It may also have a type of clamp to keep it secure. Barbs are made of plastic if they carry cold water and brass if they carry hot water.

Coupling

A coupling makes it easy to connect two pipes that have the same diameter and are the same type. It’s also used to repair a broken or leaking pipe. Along with a normal coupling, two other types are the compression coupling and slip coupling.

The compression fitting is connected between two pipes via rubber seals or gaskets on both sides which prevents leaking. A slip coupling includes two pipes, one of which slides out of the other pipe to a various length, to repair a specific length of damaged pipe.

Cross

A cross fitting has openings on all four of its ends and can connect four pipes. Cross fittings come with three inlets and an outlet or three outlets and an inlet.

Because they are the connecting point for four pipes, they are under more stress than other types of fittings and typically built tougher than other fittings.

Double Tapped Bushing

This is a type of nipple, but it has threading on both the inside and the outside. Because this center hole is threaded (tapped) from both top and bottom, it’s referred to as double-tapped.

A double tapped bushing is also a type of reducer, but does not have a reducer’s flexibility. A double tapped bushing is usually female.

Elbow

Not surprisingly, this sort of fitting has a bend that reminds you of the arm joint. They help the flow of water change direction. Elbows come in several degrees, including 22.5, 45, and 90 degrees.

Reducer elbow variations also exist for when the piping diameters being connected are different. Elbow fittings can be made of different materials, and most are female.

Mechanical Sleeve

This connects two pipes through the use of a screw or other device. This makes the fitting easy to install. The mechanical sleeve or coupling is usually made of rubber that is inserted inside a metal jacket (stainless steel clamp).

When the clamp is tightened, it compresses the rubber inside to make a tight seal. Because this fitting can be slightly flexed, it can accommodate small misalignments in hard to install locations.

Nipple

This is a short fitting that can be made of metals such as copper, brass or steel or chlorinated polyvinyl chloride (CPVC). Instead of connecting two pipes, a nipple connects two fittings.

If it has a continuous threading, it is a closed nipple. They are usually male and come in varying lengths.

Plug and Cap

Plugs and caps are both used to close up pipe openings during inspections and repairs. The main difference is that a plug is male while a cap is female. Most often, caps and plugs are threaded.

Plugs and caps are made of several materials, including metal, plastic or rubber and can be welded, soldered, glued, or threaded into the pipe.

Reducer

This fitting makes a flow smaller and thus reduces it. Reducers come in two types. The concentric reducer joins two pipes on the same axis, and the eccentric reducer is used to join pipes of different diameters.

The concentric reducer looks like a cone, while eccentric reducers look somewhat like bells with offset center lines. They prevent air bubbles in the pipes.

Tee

A tee has an inlet and an outlet and is shaped like the letter “T.” These fittings come in different sizes and are considered sturdier than the cross fitting.

A diverter tee is used in heating systems that use water. They come with directional markings and need to be installed correctly for the system to operate.

Union

Unions can have either male or female threads. They are similar to couplings, but the difference is unions are easy to remove making them convenient for maintenance or a planned future replacement.

A coupling, on the other hand, is more permanent and needs to be cut out. A union contains three parts: nut, male end, and female end. The nut is used to join the male and female ends.

Valve

Valves allow the flow of fluids to be adjusted. There are different types, including throttling, non-return and isolation. Non-return valves only allow the liquid to flow in one direction and are often found in drains. They’re also called check valves.

Isolation valves sequester a part of the plumbing system so that the system can be serviced or maintained. These valves are either left open or left closed all the time. However, because they may need to be used in a emergency, they should be checked now and then to see if they’re operational.

Throttling valves control the pressure and amount of a fluid. Because this stresses the mechanism, they tend to wear out faster than other valves. They are usually installed near isolation valves.

Wye

Built in the shape of the letter “Y,” this fitting is made to connect three pipes. Y fittings allow the pipes to change their elevations and to branch out into fresh water lines or drains.

Wyes are similar to tee fittings but the smoother angling reduces friction and turbulence in the water. This fitting is most commonly used to connect a vertical drainpipe to a horizontal one.

https://www.waterheaterhub.com/types-plumbing-pipe-fittings/