Effects of interventions in the distribution network on the existing microorganisms: DNA techniques offer clarity

Earlier research by Evides Waterbedrijf revealed that the number and composition of microbial populations can change during the distribution process of drinking water. This 2018 research was undertaken in three supply areas with drinking water produced from surface water; Next Generation Sequencing (NGS), an advanced DNA method, was used to determine the microbiology. The present follow-up research should show what impact different interventions in the distribution network have on the existing microbiology (population and processes), and how this potentially influences the drinking water quality. The study thus contributes to the provision of safe and clean drinking water, but also to the search for a good indicator for the biological stability of drinking water.

Next Generation Sequencing

Evides Waterbedrijf supplies drinking water from several sources: surface water (87%), groundwater (10%), and dune infiltrated surface water (3%). Extensive research is carried out for the purpose of improving the biological stability of this drinking water during distribution in selected and isolated areas. NGS is one of the techniques applied in the research. This molecular technique is used to examine the diversity of the microbial populations present in the drinking water distribution system.

Testing four types of interventions

The 2018 research showed that the change in the microbial populations already starts right after the high-pressure pumps at the production locations. Water quality, temperature and residential time are all factors that influence this change. The interventions that Evides wants to investigate in this new research are the following:

  • ultrafiltration (UF), which removes nutrients and microorganisms;
  • intensive purification in a selected area in combination with UF;
  • supply of biologically stable dune filtrate instead of treated surface water;
  • local UV disinfection to lower Aeromonas numbers in the distribution area.

In this new research, we will jointly apply NGS with Evides to determine the effect of these interventions on microbial drinking water quality.