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We studied plastic pipes - large variations in the quality of PEX pipes

12/20/2017

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VTT Expert Services was involved in a study funded by the Ministry of Social Affairs and Health and the Ministry of the Environment that investigated the dissolution of chemicals, especially tert-Butyl alcohol (TBA), from PEX plastic pipes into domestic water.

 

The study included long-term tests simulating real use in the pilot network of the WANDER Nordic Water and Materials Institute.

Dissolution was also investigated in short-term laboratory tests by VTT Expert Services. In the tests, ultrapure water was left to stand in the pipe samples for 3x72 hours. In addition, a sensory evaluation was carried out at the VTT Expert Services laboratory on one sample used in the long-term tests. It was found in the evaluation that a plastic taste and smell was transferred from the pipe into the water.

The concentrations of TBA, MTBE, ETBE and TAME in the water samples were measured. In addition, the effect of the duration of contact between the water and the PEX plastic pipe on the amount of TBA in the water sample was studied.

Quality differences discovered in the results

Based on the research results, the quality of the PEX pipes used as water pipes varies considerably, even between the products by the same manufacturer. To prevent this, it is recommended that the self-monitoring of the factory's production process should be developed further and the testing of production lots increased.

However, the concentration of TBA dissolved from the PEX pipes did not exceed the planned limits in either the long-term testing or the laboratory testing. In addition, the concentrations of all studied compounds in the water samples decreased with time.

In fact, the most chemicals dissolve from plastic PEX pipes when the pipe is being commissioned. For this reason, it is important to flush the water system of a building when it is commissioned. The health risks of substances that have dissolved into the water from the pipes can be reduced by running the water until it is cold before drinking it or using it in cooking.

More information about the study

The study was carried out by Martti Latva, PhD, Tuija Kaunisto, MSc (Tech.), and Aino Pelto-Huikko, MSc (Tech.), from the WANDER Nordic Water and Materials Institute of the Satakunta University of Applied Sciences (SAMK) as well as Jari Kiuru, MSc, from VTT Expert Services Oy. The research group's expert on the effects of chemicals on health was Research Professor Hannu Kiviranta from the National Institute for Health and Welfare (THL).​

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