Green Means

Choosing Safe Water Lines

By Shannon Scott

            Forget the mouse trap; the person who develops green, safe, potable water pipes may win a Nobel Prize for chemistry.  We expect potable water lines to be safe and last forever without problems.  Yet given that green home building considers a product’s sum total environmental impact, from manufacture to reuse, there is no good option for residential water lines. 

Copper

            Copper proves an environmental problem since it is extracted through open pit mining.  Processing copper ore requires significant amounts of water.  Often there is increased water pollution from discharged mine effluent and seepage from tailings and waste rock impoundments.  Water was referred to as “…mining’s most common casualty” (James Lyon, interview, Mineral Policy Center, Washington D.C.).  Given diminishing global fresh water supplies and disruption of natural landscapes copper is not a green choice.

            Over time, copper pipe can develop pinhole leaks.  These result from small localized corrosion spots called pitting corrosion. There’s no definitive data to isolate the cause.  Some theories include electrostatic charges from electrical systems being grounded through the plumbing, too low or too high water pH, or chemicals used in municipal water treatment.  Pitting corrosion gives copper pipes a 20 – 50 year life span before replacement.

            While copper is a necessary mineral for humans, cases of copper toxicity are rare but may occur where pH levels are below 6.5.  Excess copper consumption may lead to liver damage.  Several home water filters on the market can reduce excess copper levels.

            Copper pipes burst when they freeze.  Once water freezes and expands, it forces right through any weak area in a copper wall.  Too many home owners have come home from winter vacations to flooded homes or to having no available water.

            Since copper withstands high temperatures, we used it for our active solar system. The pipes don’t carry potable water.  They are filled with a propylene glycol (relatively safe antifreeze) and water solution that circulates from a header on solar collectors into a heat exchanger tank, and into floor radiant PEX tubing.  If or when we get a leak, it will be in the attic.  Hopefully we can catch it early.

            Copper’s biggest advantage is that it can be recycled.  Recycled copper can be used for fine enameled wires, power cables, more pipes, and element in gun metals, and bronzes.   

                                                                          PVC        

            Poly-vinyl chloride, or PVC is an organochlorine.  Its manufacturing contributes dangerous impacts to the environment.  The EPA has increased enforcement against the PVC manufacturing industry, which is responsible for the majority of our nation’s air emissions of toxic vinyl chloride (VC). VC, an odorless gas, is a known human carcinogen, endocrine disruptor, and linked to neurological disorders.  

            PVC pipes are designated with either "NSF-PW" or "NSF-61" to indicate that the product complies with the health effects requirements of NSF/ANSI Standard 61 for potable water.  This standard also establishes similar guidelines for other plumbing materials, including copper tubing.  If pipe is not coded with one of these designations or if it is designated with an alternative code such NSF-DWV (waste pipe) it should not be used for potable water applications.  We used some PVC in our pump house and underground, but I don’t feel good about it.

            When PVC pipes are no longer used, recycling poses a challenge.  More than 7 billion pounds of PVC are thrown away in the U.S., and only 18 million pounds – barely one-quarter of 1 percent – is recycled.  The additives used in the production of PVC inhibit recycling.  

PEX

PEX, cross-linked polyethylene, is much less toxic to produce than PVC.  PEX is flexible, resistant to scale and chlorine, doesn't corrode or develop pinholes, is faster to install than metal or rigid plastic, and has fewer connections and fittings.  PEX plumbing has been in use in Europe since about 1970, and was introduced in the U.S. around 1980.  

In California, a PEX environmental impact report (EIR), found that methyl tertiary-butyl ether (MTBE) and tert-Butyl alcohol can leach from PEX in amounts that exceed taste, odor and health guidelines set by the State of California for drinking water.  The EIR also found that PEX can leach ethyl tertiary butyl ether (ETBE), a chemical in the same family as MTBE.  A toxicologist report commissioned as part of the EIR found that the ETBE leaching from PEX pipe could contribute to taste and odor impacts, and could potentially lead to adverse health effects.  No serious adverse health problems are known at this time.

            Sunlight can dramatically reduce the PEX’s resistance to chlorine and result in premature pipe rupture.  Care should be taken to keep PEX out of direct sunlight. 

We used PEX for potable water lines.  It’s easy to install, red tubing for hot, blue for cold, and the expansion type fittings are tightly secured.  PEX is flexible, expandable, and resists cracking or bursting.  While poorly attached fittings may cause leaks, PEX tubing is highly resistant to problems as long as installation is performed with integrity.  

            PEX cannot be recycled.  A 2005 report by the San Francisco Department of the Environment found that PEX was the only type of plastic piping that no plastic recycler would accept.

Potable water pipes, at this time, are not green products.  Choose the best for your situation, and remember that just because a material can’t be recycled doesn’t mean it cannot be reused.  Think of copper art, PVC flotation devices, PEX weather stripping.  Be resourceful and think green.