Use of alternative drinking water sources demands close collaboration within the water system

The trusted groundwater and surface water sources for drinking water are under pressure from existing and new threats. As stressed by Vewin, this preoccupying picture points to the absolute need for more measures to improve the quality of the sources. Furthermore, to be well prepared for the future we need to look at possible alternative drinking water sources. KWR conducts research to this end within the Joint Research Programme of KWR and the water utilities.

29 alternative sources

In its futures study, KWR identified 29 possible alternative drinking water sources, and looked at key criteria, like availability, exploitability and quality. This involved water from surface water, the subsurface, residual water, the atmosphere, or water generated from fuel combustion. A selection was made from these 29 alternative sources of the most suitable ones on the basis of their availability, exploitability and quality.

Every water source could constitute a source for drinking water, but only if it meets key criteria like availability, exploitability and quality.

Scenario study

In addition, three scenarios were elaborated for a fictional environment with a city, a village, farms and industry.

• The first scenario assumes the use of local sources, like rainwater, and maximum water savings. In addition, greywater is treated and used as household water.
• The second scenario is based on a circular economy, in which WWTP effluent and residual water from the food industry are used as sources. Here, too, greywater is treated and used as drinking or household water.
• The third scenario takes into account an increasing level of water consumption and sharp climate changes, so that brackish groundwater is used as the most important drinking water source, complemented by residual water from the food industry.

Treatment schemes and costs

The selection of the most suitable of the 29 alternative sources was examined in the scenarios. Among other things this involved formulating treatment schemes: What treatment methods are needed to produce good drinking water from the alternative source? The costs of such treatments were also estimated. The research shows that in many cases there will be alternative local sources that can be used to make drinking water.

Good collaboration with all stakeholders

Small-scale, local treatment processes are generally more costly than centralised drinking water treatment. However, depending on the local conditions, the exploitation of such sources might still be of interest. But this will have implications for drinking water utilities, society and the surrounding environment. In all three scenarios the use of local sources requires good collaboration between all stakeholders in the whole water system. This applies for instance to the application of the necessary technical advances, such as the development of online sensors, legal and regulatory frameworks, and the closing of water cycles, or parts thereof. A robust drinking water provision means that all the different interests must be carefully considered, and that water systems must consequently be viewed in their entirety.

If the current drinking water sources come under even greater pressure in the future, there are thus alternative sources available that can technically be used. Switching to these sources will however have consequences for all stakeholders in the water sector. Closer collaboration between the drinking water utilities and other stakeholders in the water system is therefore becoming increasingly important.