Heuvelstraat, a waterneutral residential area - closed loop approach - Reference

Project's context & challenges

In the rural village of Silvolde, located in the Dutch Achterhoek region, the Heuvelstraat pilot project tackles a growing regional crisis: prolonged droughts caused by sandy soils and declining groundwater levels, combined with increasing pressure on the drinking water supply due to urban development. Traditional centralized water systems—where rainwater is drained away and wastewater transported to distant treatment plants—no longer provide a sustainable solution.

The challenge: design and implement a decentralized, circular water system that allows residents to live water-neutral and sewageless, by harvesting and reusing water within each household.

Key figures

28 homes

Designed to be water-neutral and sewageless

Up to 100%

Reduction in drinking water usage

Up to 40%

Drinking water savings through greywater reuse

Customer benefits

Reduces pressure on regional drinking water supplies

Provides climate-resilient, decentralized water infrastructure

Enhances drought resilience through local rainwater storage

Eliminates the need for central sewer connections

Demonstrates a scalable model for rural and urban settings

Residents gain awareness and ownership over their own water cycle

Solution

Nijhuis Saur Industries partnered with local authorities, residents, Vitens (the regional drinking water company), and other stakeholders to create a fully decentralized circular water system for the Heuvelstraat.

Key innovations include:

Rain-to-drinking water conversion using sand filtration, nanofiltration, and UV disinfection
Hydraloop greywater recycling for reuse in toilets and garden irrigation
Blackwater purification through a local treatment unit producing infiltration water and compost
Smart metering and monitoring to track performance and usage patterns

The system closes the water loop at household level, making every drop count — and ensuring water is used, reused, and returned to nature sustainably.