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New University Study Proves Superiority o CPVC Relativ Relativee to Taste, Odor and Leaching Leachi ng Concerns Copper and Five Dierent Polymer Pipe Materials Tested to Compare Perormance Using Multiple Water Treatment Disinectants
“Results indicate that copper pipe consumed nearly all the residual
Water quality – both rom a health and saety sta ndpoint, as well as a
disinectants… results or the polymer materia ls indicated that CPVC
taste and smell perspective – should be a primar y concern whether you’re you’re
imparted the ewest organic compounds to the water, consumed the least
installing hot and cold water d istribution piping into a consumer’s home
amount o disinectants, and produced no noticeable odors. All other
or a commercial ood or beverage processing plant. The boom in the
polymer materials imparted distinct odors and organic chemicals to
bottled water industry is proo that consumers are sensitive sensitive to noticeable
water and consumed residual disinect ant.”
tastes and odors in the water t hey drink, a nd they’re they’re willing to go to extra eorts and even pay more or more aesthetically-pleasing aesthetically-pleasing water.
The Virginia Tech study is not the rst to examine the sensory impacts rom polymer pipes interacting with drinking water oxidants. What
The Civil and Environmental Engineering Department o Virginia Tech
makes the study un ique, however, however, was that both chemical and consumer-
recently conducted a sensory impact study on various piping materials in
assessed sensory characteristics o water in contact with the materials
regard to the possible leaching o polymer additives, organic compounds
were compared. A trained human panel used Flavor Prole Analysis
and oxidation o the surace o the pipe during extrusion – all o which
to assess odors. A chemical process commonly reerred to as SPME-
can aect the taste and smell o the water.
GC-MS (or more ormally known as solid phase m icroextraction-gas chromatography-mass spectrometry), which utilizes var ious ber
This study leaves no doubt that CPVC is the preerred choice rom a
elements to extract compounds in the water, was used to dete ct and
taste and smell viewpoint, as well the absorption o disinectants used
identiy organic components. And total organic carbon was determined
in the water trea tment process. Whether you’re a contractor working in
using an automated Sievers Sievers® 800 Portable TOC Analyzer.
new construction or remodeling, or the engine er or specier or a major commercial or industria l project, it’s it’s important to understand water
The study urther took into account recent changes in water treatment
quality changes imparted by pipe materials in order to make smart
in the U.S., including the increased use o monochloramines to disinect
decisions relative to the products you use.
water instead o chlorine. Both chlor ine and monochloramine levels were determined using the DPD (diethyl-p-phenylenediamine) (diethyl-p-phenylenediamine) method,
which is a popular testing technique used to monitor water quality in
There are many considerations when choosing a piping material – cost,
both pools and spas across the globe. Through this test, a tablet interacts
reliability, saety, saety, long-term maintenance requ irements, to name
with the water to turn it a shade o pink, depending on the intensity o
just a ew. ew. In rec ent years, polymer pipes have gained market share
the chlorine concentration in the water.
particularly in residential but also in commercial applications because o their superior perormance in all o these areas.
The test was designed to accomplish two objectives: (1) to investigate the sensory properties o water with either chlorine or chloramines when
One questionable area regarding t he use o polymer materials, however,
it came into contact with di erent piping materials; (2) to i nvestigate nvestigate
has been the possible introduction o perceptible tastes and odors that
changes in residual disinectant and leaching o organic chemicals rom
either occur duri ng the extrusion process or dur ing the pipe’s pipe’s interaction
pipe when in contact with drinking water.
with various water treatment disinectants. The study conrmed that not all plastics produce the sa me results with regard to the possible leaching
All testing was conducted under “typical” drinking water quality
o polymer additives, organic compounds and oxidation o the surace o
conditions. The Utility Quick Test, a standard leaching protocol
the pipe during extrusion.
or new materials, was conducted at room temperature using a low alkalinity water o pH 7.8-8 with no disinectant, 2 mg/L chlorine,
Specically, CPVC CPVC perormed consistently higher when compared
or 4 mg/L monochloramine. This test consisted o three consecutive
to copper, high-density polyethylene polyethylene (HDPE), epoxy lining a nd the
72-96 hour leaching/fushing periods and included triplicate testing o
PEX piping selected or the study. In act according to the report:
all pipe types.
Results comparing the polymer materials indicated
As or copper, the results indicate that it consumed
that CPVC imparted the ewest organic compounds
nearly all the residual disinectant but released ew
to the water, consumed the least amount o
organic compounds or odors.
disinectants, and produced no noticeable odors. All other polymer materials imparted distinct
The below table summarizes the impacts o the
odors and organic chemicals into the water and
various polymer piping materials on both the sensory
were shown to consume residual disinectant.
(taste and smell) and chemical quality o drinking
O all the materials tested, epoxy lining had the
water. It is interesting to note that while some
most dramatic eect on water quality, imparti ng a
materials perormed well in certain categories, they
moderate “plastic-putty-glue” odor, leaching 0.4-
under-perormed in others. The best-perorming
0.6 mg/L organic car bon including the compounds
PEX pipe, or example, leached the greatest amount
bisphenol A, styrene, toluene, nonylphenol and
o organic carbon, as well as the greatest number o
benzaldehyde. It also consumed nearly all the
volatile organic compounds, but did not c ontribute
residual chlorine and chloramines.
the most intense odors (although it did contribute a variety o odors). HDPE leached only a minor
In contrast, HDPE consumed a low amount o residual disinectant and
amount o organic carbon (but many specic organics) yet imparted the
released only about 0.1 mg/L organic ca rbon to the water including
greatest odor intensity.
phenol, bisphenol-A, tetradecane, cyclohexadiene, cyclohexanone, and cyclopentanone. The overall odor imparted to the water rom HDPE
Only CPVC perormed consistently well across the categories. Not only
had a moderate intensity and was described as “waxy/plastic/citrus.”
did it leach the least amount o Total Organic Compounds (TOC) and
Panelists described the HDPE odor as “chemical/plastic” in the presence
have the ewest number o compounds identied by SPME-G C-MS, but
o chlorine and “waxy-crayon/plastic” in water with chloramines. The
it also had the least impact on water aesthetics, which meant there was
presence o disinectants did not appear to alter the intensity o the
no oensive taste or smell to water fowing through CPVC piping. Not
odors. Despite their overall similar ities, various PEX piping products
only does this conclusion support the selection o CPVC but it suggests
perormed dierently in the tests, with some pipe producing more
that it is the specic organic chemicals and not the concentration o
odors than others. Water in contact with the best perorming PEX
organic carbon present in the water that determines odor intensity and
product possessed weak to moderate intensity odors, leached about
aesthetic impact. Additionally, there did not appear to b e any correlation
1 mg/L organic carbon, and consumed up to 0.5 mg/L ree chlorine.
between the type o disinectant and amount o organic carbon leached.
Ethyl-t-buyl ether (EtBE) was ound to contribute signicantly to the
Both chlorine and monochloramine had minimal eect on the intensity
characteristic “burning-solvent/plastic” odor o the better perorming