Whether PVC water pipes are safe for potable water is a matter of some debate. While PVC pipes are certainly safer than lead pipes, copper is often deemed the more reasonable choice for internal home water plumbing, and PVC is not safe for potable hot water. CPVC is safe for hot water; however, there are some important pros and cons in the debate been plastic and copper piping.
For internal plumbing, copper is considered the gold standard, particularly since PVC is not safe for hot water. Once the piping is past your home's water heater, it makes the most sense to use piping that can support hot and cold potable water. So, the question is, why use PVC at all?
CPVC (chlorinated polyvinyl chloride) can be used for both hot and cold water, eliminating the confusion of internal piping past your water heater.
Some of the downsides to both PVC and CPVC include strong solvents in the glued joints and environmental concerns during production. There's also some concern about a "plasticky" taste from water fed through either type of PVC pipe. That leads to another debate about the leaching of chemicals into the water from the pipes. The leaching usually abates after several months, but there is not sufficient research into any health risks during the initial stages of PVC installation.
Flexible PEX solution
The flexible PEX tubing solution is becoming popular for internal plumbing. Flexible PEX is easy to install and has the benefit of a lack of strong solvent glues at the joints. However, the plasticky taste from chemical leaching and subsequent health questions remain in this type of pipe. If choosing PEX or PVC, a water filter may be used to rid the home water supply of leached chemicals.
PVC safer than lead
Replacing lead piping in older homes is highly recommended, as lead poisoning from lead leaching into the home water supply is likely. Lead is one of the most significant environmental health threats. So, if you have lead piping and PVC or PEX tubing is your only viable solution, it should certainly be considered.
However, vinyl chloride (an ingredient of PVC) has been found to be carcinogenic. After that was discovered, regulations limited the amounts of vinyl chloride allowed in PVC water pipes. However, EPA-allowed amounts still exist. The greater concern is in the solvents used to glue the joints and in the metallic components used to guard the piping from heat degradation.
CPVC vs. copper
Copper can be more expensive and more difficult for a do-it-yourselfer to install. It also has the issue of corrosion, while CPVC can last quite a bit longer. Copper is also an electrical conductor, which allows you to ground your electricity. CVPC requires special glues to join, while copper requires soldering.
Copper is also better at lasting through extreme temperatures than CPVC, so since the Atlanta area has extreme summer seasons, copper may be the better choice.
Both PVC and CPVC will melt in a building fire and can harbor bacteria on the interior surface. And the joint compounds are known pollutants and toxins. Another downside to CPVC compared to copper is the requirement of ventilation during the installation process. Copper soldering requires no such ventilation.
PEX tubing vs. copper
First off, PEX tubing is significantly cheaper than copper. PEX also has fewer fittings and is burst-resistant since it's flexible. It allows for a significantly easier installation due to the lack of joints and elbows as it can turn around corners. It's significantly less skill-intensive than copper piping installation. And, once a somewhat expensive special crimper is purchased, there isn't much capital output for the PEX tubing installation. It has a shutoff valve at every supply line, which aids in repairs.
Some of the disadvantages include the fact that, due to UV sensitivity, it cannot be used outside. It also can't be recycled. The piping is an impermeable membrane, which may allow water contamination over time from the surrounding ground.
Comparatively, copper is bacteria-resistant and resists corrosion. It's not affected by UV rays, so it can be installed outside. Copper is recyclable, making it a better choice environmentally. However, there is some recent evidence that PEX piping has potential to be a greener choice than it may initially seem. Its strengths in durability, water conservation and energy efficiency earn it points in the environmental realm.
Copper can corrode and is quite expensive, relative to the plastic piping options. Once the piping corrodes, it can give water a metallic taste.