project

Survival and growth of water lice on organic matter in drinking water distribution networks

Expert(s):
Nikki van Bel PhD

  • Start date
    01 May 2019
  • End date
    01 Nov 2020
  • Principal
    Joint Research Programme
  • collaborating partners
    Evides

Earlier research has indicated that a correlation exists between the presence of water lice and the Aeromonas count in drinking water, and that this bacterium probably partly lives in or on water lice. But water lice are not present at the same levels in all distribution networks. Their presence presumably depends on the quality and composition of the food, but how this works precisely is not clear.

The objective of this research is to determine the possible connection between the survival and growth of water lice and the composition of sediment from different distribution networks. The explanation of the heterogeneity of the presence of water lice in distribution networks will bring control measures within reach.

Water lice on maple leaf

Clarification of role of sediment composition in the presence of water lice

Water temperature and organic matter play an important role in the growth in drinking water of protozoa, invertebrates and bacteria such as Aeromonas. This has been demonstrated by research over the last few decades. Aeromonas is a harmless bacterium that is used as an indicator for the biological stability of the drinking water, and its count must remain under the legal standard of 1000 CFU/100 ml. The presence of water lice is one of the factors that correlates with the growth of Aeromonas in drinking water, and the bacterium apparently grows on or in this invertebrate.

It is not known why water lice are not equally present in all distribution networks. Presumably the quality and the composition of the available food (sediment and biofilm) – which are a function of the water quality in the particular area – are determining factors for the survival and growth of water lice. These factors therefore also directly or indirectly affect the growth of Aeromonas. The objective of this research is to determine the possible connection between the survival and growth of water lice and the chemical and microbiological composition of sediment from different distribution networks.

Growth and survival of water lice in sediment

In growth and survival experiments, water lice are being grown in the presence of sediment taken from different distribution networks. The chemical and biological composition of the different sediments is also being determined. This makes it possible to ascertain which elements have a positive or negative impact on the length-growth and survival of water lice.

Water lice in grow box with sediment and faecal pellets

Making control measures possible

This research will provide greater clarity about a possible connection between the biological stability of the drinking water, sediment and the presence of water lice and Aeromonas. Insofar as possible, it will also explain the heterogeneity of the presence of water lice in distribution networks, which would bring control measures within reach.