Putting Pipe Material to the Test

Why Pipes Need to be Treated as Living Things

The specification of pipe material for water distribution system installation is often based on operational or financial factors. Unit cost, installation time and logistical considerations such as transportation and storage come into this important decision.

However, the way we specify type of pipe material, especially that which is required for hot and cold water for personal use, must also come from the perspective of water quality and resistance to microbial growth.

FlowGuard® CPVC is engineered with safe distribution of water in mind. Not only is it easy to install, but proper installation of CPVC pipes and fittings creates an environment for water that preserves quality and safety for its users.

It is better to think of water supply lines as living things, as they can be host to living organisms that could harm the quality of your plumbing system, as a recent study shows.

The Influence of Pipe Material on Drinking Water

The KWR Water Research Institute conducted a study to investigate the influence of pipe materials on the microbial community in unchlorinated drinking water and biofilm. 

Six different piping materials and a sample of glass were suspended in drinking water and incubated for 16 weeks, with a fresh replacement of water at regular time intervals. The samples and the biofilm that formed inside were measured for BPP (biomass production potential.) 

The test was to determine the extent of negative impact pathogens can have on drinking water distribution, through biofilm. 

The six piping materials were:

• Copper pipe
• PVC-C (Chlorinated Polyvinyl Chloride (CPVC))
• PE-Xb (Polyethylene crosslinked with silane) 
• PE-Xc (Polyethylene crosslinked with electron beam)
• PE-100 (Polyethylene density 100)
• PVC-P (plasticised PVC)

What Type of Plumbing Pipe is Best?

The study confirms that pipe material does have a biological effect on a number of factors:

• Biomass concentration
• Numbers of specific organisms
• Bacterial community composition

• PVC-P showed a distinct bacterial community composition and a high biomass concentration, compared to other materials.

• PVC-C (CPVC) was identified as “the preferred material to control microbial growth in drinking water systems compared to the other plastic materials analyzed in this study.” CPVC also displayed a lower concentration of microbial communities than any of the Polyethylene/PEX pipe materials. 

Why CPVC helps control microbial growth

According to the study, With PVC–C, which has a biomass concentration that is slightly higher than for glass (indicating release of small amounts of growth promoting substances), a lower water biofilm ratio for ATP was observed, demonstrating a shift of biomass from water to biofilm. 

Since the absolute ATP concentration in water in contact with PVC–C is the same as for glass, the extra growth with PVC–C only occurred in the biofilm.

This means that CPVC is fundamentally better at controlling microbial growth than other plastics, due to its very limited susceptibility to biofilm. While biofilm does form and while such biofilm does carry pathogenic potential, it cannot successfully accommodate as much biofilm as its plastic counterparts.

Therefore, the challenge for specifiers is controlling microbial growth and limiting the potential for risk to public health. 

We Need to be Preventing, Not Repairing

In a recent interview with FlowGuard CPVC, Dave Purkiss of NSF International explained,  “to achieve water safety, you need a preventative approach.” The specification of pipe material can have a direct and lasting influence on water safety.

FlowGuard CPVC is recognised and certified by NSF International as safe for drinking water distribution. When PVC becomes CPVC, its resistance to biofilm formation and therefore development of bacterial communities increases significantly. As this study demonstrates very clearly, not all pipe material is the same. 

Learn more about the importance of pipe material for water safety in our exclusive interview series here.

To find out more about this subject, listen to this episode of the FlowGuard podcast