Hey Reader,

When I first looked into the impact on water at my employer three years ago, the initial conclusion was almost embarrassingly simple.

We don’t consume much freshwater. A bit for the toilets. The coffee machine. Our precast concrete production runs on stored rainwater.

Most buildings today designed according to BREEAM or similar standards often use little water during operation.

So the initial reaction is to assume construction does not really have a water issue.

But then you realise that your project might be in a high water stress area and you’re much more dependent on water than you might think.

What the heck is water stress?

Water stress measures how much pressure human activities place on local water resources.

Surprisingly, parts of Europe score very high on this metric. Flanders, the northern region of Belgium, is one of them.

For real. Despite all the rain.

Belgium ranks 18th out of the 25 countries in the world that experience extreme water stress every year. It is the only northern European nation that high in the ranking.

Let me explain why Flanders specifically is in trouble.

No natural water storage. Belgium has almost no natural lakes. There is nowhere to hold water when it rains. Compare that to Germany, where Lake Constance alone supplies drinking water to entire regions including my former hometown. Or Denmark, where a different geology creates natural buffers. Belgium has nothing comparable.

Sixty percent of available water drains to the sea. In total, around 60% of all water available in Flanders flows lost to the sea via rivers, drainage systems and sewers. It rains enough. The water simply leaves before it can be used.

Extreme soil sealing and high population density. Almost the complete triangle from Ghent to Antwerp to Brussels is urban area. That density means concrete, asphalt, driveways, parking lots, terraces. Surfaces that rain cannot penetrate.

The combined result is a imbalance between what Flanders withdraws and what is actually available.

Flanders uses over 80% of its renewable water supply every year. Water stress becomes extreme when that ratio crosses 80%.

Almost no region in the world at that level has a rainy climate. Flanders does.

Which role does construction play?

The built environment is itself a cause of Belgium’s water stress problem.

Green areas are progressively replaced by concrete and asphalt, preventing water from infiltrating the soil and recharging groundwater systems.

Every new impermeable surface a contractor builds makes the regional groundwater situation worse. There is a direct link between construction activity and the depletion of the very resource construction depends on.

In Flanders, over ten years, from 2013 to 2023, more than 21,000 hectares of sealed surface was added, an average of 5.8 hectares per day. The biggest contributors are not new buildings. They are roads, driveways, terraces and parking areas.

And then there is dewatering.

When you dig deep enough to hit the water table, you pump the water out.

On a 40 by 25 metre construction pit with two underground levels, that is around 100 m³ per hour.

In Flanders, around 90% of that pumped groundwater ends up in the sewer.

On sites where the water is not contaminated it is essentially clean groundwater. Infiltration back into the soil, reuse on site for dust suppression or cleaning are all better options.

Once it enters the sewer, it is gone.

Dependencies

We speak often about the impact of construction. Too much CO2. Too much waste. Soil sealing.

But we don’t speak that often about dependencies. Me included, to be honest. It’s more complex.

And yet, it goes much further than the regular sustainability topics.

Dependencies literally explain whether and how much you depend on something. These dependencies could distract or stop business operations.

So which dependencies are there with water?

Transport via waterways. Concrete plants, precast manufacturers and contractors depend on waterways to move huge quantities of material.

Soil removed from construction sites. Precast elements. Steel structures.

Inland shipping is often the only realistic option for the volumes involved.

When river levels drop during drought, that supply chain stalls. The Rhine and the Albert Canal have seen cargo restrictions in recent dry summers. It is a dependency most construction companies have never mapped.

Water as ingredient in concrete. It is so obvious that we tend to forget it.

Water is a key ingredient of concrete. Between 150 and 190 litres go into every cubic meter.

Droughts are a risk. Spain’s industrial sector faced a 25% water allocation cut during the Catalonia drought in 2024.

No water equals no concrete. Concrete producers, and everyone in construction using their product, are clearly dependent on a reliable water supply.

Multinational Holcim is already acting on this. Their plant in Tit Mellil (Morocco), now uses treated municipal wastewater for concrete mixing instead of freshwater. A dedicated tank and pump system connected to a local wastewater treatment facility. They report a 30% reduction in freshwater withdrawal at that site.

Holcim has committed to a 15% reduction in freshwater withdrawal across the ready-mix segment by 2030.

Access denied to drinking water connections. You have probably heard about grid congestion in the Netherlands and parts of Belgium. Developers cannot get electricity connections. Projects stall.

The same thing is now happening with water.

By 2024, Vitens, the largest Dutch drinking water company, had refused 45 companies a new drinking waterconnection. They have warned that new residential developments in some areas may not be connectable to the drinking water network at all.

We are not speaking about sub-Saharan Africa. It’s the Netherlands.

Where it stopped: Port of Urk, Flevoland. Port of Urk is a new 100-hectare industrial development zone in the Ijselmeer area, designed specifically for the expansion of the Dutch fish processing industry. Roads and sewers have been built. Plots have been sold.

But the fish processing businesses hoping to establish themselves there cannot get a drinking water connection for large-scale use.

There is a stop on all new large connections for the entire region. No structural solution is expected for at least ten years.

Take-away

Let’s stop taking water for granted.

While the immediate costs are low, the implications can be huge. Especially on the dependencies side. Every impact increases the chance that dependencies become constraints.

Three things worth doing now.

Start measuring water withdrawal on your construction sites. Not just consumption. Dewatering volumes included. Most companies have no idea what these numbers are.

And on deep excavation projects, have the conversation about dewatering water early. Infiltration on site is almost always the best answer where the water quality allows it.

Check whether your projects are in water-stressed areas.

Tip of the week The WRI Aqueduct Water Risk Atlas A free tool, no login needed. Takes two minutes. Go to the Aqueduct Water Risk Atlas. Scroll the map to your project or office location and zoom in. Once a location hits the dark red end of the scale, it means more than 80% of available renewable water is being withdrawn every year. The red area is high water stress and there are plenty. Southern Netherlands, Berlin, Southern-Western Germany. On the left panel you can switch between layers. Baseline water stress is the main one to understand. But also worth checking: groundwater depletion and riverine flood risk. Together they give you a realistic picture of both drought risk and flood risk for any project location. One practical step: before your next project kicks off, run the location through Aqueduct. It takes two minutes and it will change the conversation in your first project meeting. Did you try out the tool, Reader? Where are your projects located?

Disclaimer

This newsletter represents my own thinking, not that of my employer or the boards I sit on. I write it because I find the topic important not on anyone’s behalf.