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Va Tech Taste Study Plumbing Contractor News

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New University Study Proves Superiority o CPVC Relativ Relativee to Taste, Odor and Leaching Leachi ng Concerns Copper and Five Dierent Polymer Pipe Materials Tested to Compare Perormance Using Multiple Water Treatment Disinectants

Executive Summary

“Results indicate that copper pipe consumed nearly all the residual

Water quality – both rom a health and saety sta ndpoint, as well as a

disinectants… 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 disinectants, 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 disinect ant.”

tastes and odors in the water t hey drink, a nd they’re they’re willing to go to extra eorts 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 Prole Analysis

and oxidation o the surace o the pipe during extrusion – all o which

to assess odors. A chemical process commonly reerred to as SPME-

can aect 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 preerred 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 disinectants used

identiy 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 specier 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 disinect

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,

Study Details

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, saety, saety, 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 perormance 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 disinectant 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 disinectants. The study conrmed 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 surace 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 disinectant, 2 mg/L chlorine,

Specically, CPVC CPVC perormed 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 disinectant but released ew

to the water, consumed the least amount o 

organic compounds or odors.

disinectants, 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 disinectant.

(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 eect on water quality, imparti ng a

materials perormed well in certain categories, they

moderate “plastic-putty-glue” odor, leaching 0.4-

under-perormed in others. The best-perorming

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 disinectant and

amount o organic carbon (but many specic 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 perormed 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 identied 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 disinectants did not appear to alter the intensity o the

no oensive 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

perormed dierently in the tests, with some pipe producing more

that it is the specic organic chemicals and not the concentration o 

odors than others. Water in contact with the best perorming 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 disinectant and amount o organic carbon leached.

Ethyl-t-buyl ether (EtBE) was ound to contribute signicantly to the

Both chlorine and monochloramine had minimal eect on the intensity

characteristic “burning-solvent/plastic” odor o the better perorming

o the odors associated with the polymer.

PEX pipe.

Impact on Drinking Water Quality

Parameter (short-term testing)

Increased Odors  – sensory annoyance

Organic Carbon Release Chlorine Consumption Chloramine Consumption



Best Performing PEX

Worst Performing PEX



























(1 indicates least impact to water quality; 5 indicates greatest impact)

The Lubrizol Corporation


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