Copper pipes commonly used in plumbing in USA have a tendency to leak due to pinholes formation.
The American Water Works Association estimates that it will cost US
water utilities US$325 billion during the next 20 years to replace losses due to corrosion and advocates the need to
upgrade water distribution systems. Nationally, corrosion of metals is believed to consume 4% of the
gross domestic product. Hence, interest has been generated in lower cost plastic pipes for plumbing in USA.
In a recent
research, scientists from Virginia Tech found that plumbing plastic pipes impart odour to water. The
sampling was part of pioneering research on how plumbing materials affect the odour and taste of
drinking water.
Virginia Tech’s scientific team has used two methods to evaluate odours associated with several types
of plastic piping. First, sensory panelists smell and describe the odour of the water after it has sat
in the pipes for several days. Then, the water undergoes chemical analyses for metals and organics and
basic water quality parameters, such as pH levels.
Using specially prepared, neutral-smelling water as their control, panelists described the test water
samples in terms that included “waxy plastic citrus,” “fruity plastic” and “burning plastic.”
Fortunately, the odours are not long lasting. How quickly the odors disappear depends on the amount
of water usage. When a household uses more water, the odours fade faster.
Several types of plastic pipes were evaluated such as CPVC (chlorinated polyvinyl chloride),
HDPE (high-density polyethylene), and PEX-a and PEX-b (cross linked polyethylenes).
Each is approved and certified for use in drinking water applications by NSF International, an
independent certification, standards and testing organization, and ANSI, the American National
Standards Institute.
CPVC has a low odour potential and it doesn’t seem to release many organic chemicals.
HDPE actually had the highest odour production, although it didn’t release many organic materials.
The PEX-b pipe had a moderate amount of odours and a moderate amount of organic chemicals that
were released into the air.
PEX-a had fewer odors and organics release than the PEX-b pipe.
The effect on public health of leached compound or chemicals is being studied.
The American Water Works Association has reported serious health and aesthetic problems that can occur from microbial growth or contaminant
leaching from metallic and concrete plumbing material. The environmental impacts from the
deteriorated plumbing include holes in pipes formed through corrosion, which allow the influx of contaminants
into drinking water systems, the loss of the water resource itself, and resultant property damage.