Abstract
A brand-new office building in Rauma, Finland, was used to study the first five years of PEX-a drinking water pipes in normal use. Both pipe material and water samples from hot and cold-water pipelines were analyzed. Migration of volatile organic compounds (VOC) from the PEX-a pipes into the drinking water was observed to decrease rapidly during the first months. Deterioration of the PEX-a material was observed to take place due to the wearing down of organic antioxidants added into the PEX-a material during the manufacturing of the pipes. Tert-butyl alcohol (TBA) concentrations were high during the first months after commissioning of use. The stagnation time of the drinking water in contact with the PEX-a material before the actual water sample was taken had a major impact on analyzed migration of organic compounds. Hence, the amount of organic compounds able to migrate from materials into the drinking water will increase when the stagnation time increases. In this study, the water samples were taken after overnight stagnation, whereas in normal use it is advisable to run water properly before drinking it. Instructions will be needed for the average user to avoid harmful health effects.
Highlights
The most typical materials in installed drinking water systems inside buildings are stainless steel, carbon steel, copper, and polyethylene
As part of a larger long-term research program related to the interactions between drinking water and materials this study focused on water supply pipes made from PEX-a material
Volatile organic compounds were analyzed from water samples
Summary
The most typical materials in installed drinking water systems inside buildings are stainless steel, carbon steel, copper, and polyethylene. Polyethylene pipes are generally either polyethylene, cross-linked polyethylene (PEX), or multilayer pipes. They have many useful features, such as long durability, corrosion resistance, low cost, and easy installation. Plastic materials used in water systems do not experience traditional corrosion, but their ageing processes have impact on durability of the pipes. Physical deterioration, oxidation, hydrolyzing, thermal decomposition, and combination of these may occur. Small differences in raw-material content or in manufacturing processes may have significant effect on to the properties of the plastic in the long run
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