Using subsurface solutions for a robust freshwater supply

At the drinking water company Dunea, fresh groundwater is extracted while extraction wells are under risk of saline groundwater upconing. In COASTAR, we are aiming on safeguarding the fresh groundwater volume increases. by extracting and desalinizing brackish groundwater to drinking water conditions.

Stage of the project




Starting Up





Why was this project started?

Fresh at hand, saline at bay (COASTAR, together with KWR, Arcadis and Allied Waters)

Our initiative opts for regional scale implementation of water resources management strategies to secure freshwater supply in coastal areas to agriculture, industry and the public. Large scale coastal Managed Aquifer Recharge and Aquifer Storage and Recovery can be used to store surpluses of freshwater until the demands peak. Interception of intruding brackish groundwater can prevent salinization of aquifers, polder areas and water well fields, while at the same time the brackish water may provide a source of freshwater after desalination. In the Netherlands, this concept is now part of water resources planning by water authorities, water companies and the (food) industry. Similar concepts are applicable in coastal areas worldwide – from urban delta’s to small islands.

The results of the project so far

Implementation of a pilot to demonstrate that brackish groundwater can be extracted and can be used for drinking water.
Desktop study on modelling the fresh-brackish-saline groundwater processes.

What are specific, distinctive, strong elements in this project?

Use the subsurface as a reserve to store the surplus of water temporarily and reuse it later when it is needed most.

Which specific lessons, do's and don'ts would you like to share? What would be suggestions for others when preparing or implementing the project in their own city?

Steps towards a climate-proof freshwater supply using the subsurface:
1. Sense of urgency on fresh ground water supply under climate and anthropogenic stress
2. Frontrunner stakeholders at every governmental level
3. Analysis of the (ground)water system
4. Open access to hydro(geo)logical data
5. Assessing the future water gap
6. Setting up piloting solutions/strategies
7. Procedure for scaling up solutions/strategies into the region
8. Open up regulations/rules
9. Communication and knowledge transfer

Have others adopted, or shown interest in adopting, your idea in their own area?

This concept works in areas where there is a lack of enough water of good quality at the right time with acceptable costs. If the subsurface is suitable and there is a moment during the year when water quality and quanity are sufficient, then a so-called Managed Aquifer Recharge system can relief the water stress

Can you tell us how valuable this project was for you?

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3. Could this project be shared to - and implemented in - your own city?
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