Goed Gietwater (demo)

Location: Westland, The Netherlands


Provincie Zuid-Holland
Hoogheemraadschap Delfland


The horticulture sector in Westland uses groundwater to irrigate their crops. However, the salinity of the groundwater in the western part of The Netherlands is increasing as a result of sealevel rise and salt water intrusion. This means that expensive desalination technology is required that produces a brine that causes environmental harm. It is expected that new policies will prohibit the disposal of brine within the next 5-10 years. The increasing salinity of the groundwater combined with the increasing frequency of droughts means that there are strong incentives for the horticulture sector to look for alternative sources of irrigation water.

Tailor-made effluents can be a reliable source of irrigation water year round. The consistent quality of effluents combined with the improved water security of supply compared to groundwater are good reasons to switch over. Options for the treatment and reuse of municipal wastewater (from the RWZI – Harnashpolder and the AWZI – De Groote Lucht) have been explored mostly from an individual technology standpoint.  It is unclear however, how the system design should look like: which water treatment technologies should be selected and especially where the pipeline corridors and storage solutions can best be located in the area. That’s where AquaVest comes in!

AquaVest to identify the optimal system design at lower CAPEX

We built a demo for the project to showcase how the different variables interact, to identify the economic tipping points to switch over to tailor-made effluents, and to determine the optimal system solution. In other words, how the (seasonal) demand for irrigation water from the greenhouses, the OPEX of the RO units, the sales prices of the crops, the timing of the legislation on brine disposal, and the available effluents from the RWZI and AWZI all play out. The CAPEX and OPEX of a number of investment options were defined, and by running a number of scenarios AquaVest produced an investment strategy to transition towards a more sustainable use of water that also improves the water security for the horticulture sector in Westland.


SDG12: Responsible consumption and production

  • Treatment and reuse of municipal wastewater as alternative source of irrigation water
  • Reduced groundwater extraction (more fresh water for nature)

SDG13: Climate action

  • Create a reliable source of irrigation water with improved security of supply
  • Reduce drought related economic damage of the horticulture sector

SDG14: Life below water

  • Reduced brine disposal leads to improved groundwater and surface water quality
  • Reduced groundwater extraction improves the area’s water balance