Whether hiring a plumber or taking on a DIY plumbing project, the experience can be confusing because of the choice of several types of plumbing pipes used for water. Eventually, pipes' uses tend to blend together. What's the right pipe 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, 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 made water-supply plumbing easier for do-it-yourselfers and professional plumbers.
Long-term capabilities untested
May leak with push-fit plumbing fittings
Cannot be recycled
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.
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
The pipe cannot be unjoined and must be cut
Glued pipes can be prone to leaking if not installed properly
Degrades in sunlight
Watch Now: Best Ways to Repair a Leaky PVC Pipe
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. Rigid copper pipe is great for water supply because it does not come with any health risks.
Handles heat well
Stands up against intense pressures
Easy to recycle and waste copper pipe even has monetary value
Difficult for do-it-yourselfers to work with due to soldered connections
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. Be sure to consult your local codes to determine where you can use this product.
Stronger than PVC pipes
Good for underground exterior use
Works well in cold temperatures
Often not permitted by building code
Warps and deforms at certain temperatures
Flexible Type Connection
Flexible connections, also called Flexi's for short, are used for final connections to appliances. Like water heaters, toilets, sinks, etc. They are used on gas & domestic water and come in many lengths & sizes. BUT local codes must be followed. They are not permitted inside walls or floors.
Fits in tight, unusually shaped areas
High heat tolerance
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 DIYers: 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 fittings.
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.
There are no pros for the use of galvanized pipe anymore. However, it is still required for use in some applications, like natural gas.
Galvanized steel pipe eventually corrodes and blocks water flow.
Some galvanized steel pipe may pass lead into the water supply.
Plumbing and Pipes: Healthier Choices. Environmental Working Group.