Why Belgian Tap Water Isn’t Cold Anymore: Climate Impact
You turn on the cold tap expecting a refreshing stream of cool water, but what comes out is tepid—sometimes even warm. This is the experience of many Belgians this summer, and it’s not a plumbing coincidence. The record-breaking heatwaves gripping the country are warming everything from the Meuse river to the pipes buried beneath sun-baked streets, and the water that reaches household taps is feeling the effects.
According to RTBF, the intense heat that has persisted since the beginning of summer is the primary culprit. Eric Chauveheid, head of the laboratory at Vivaqua—Brussels’ water producer and distributor—explains that surface water sources are particularly affected. “We capture, for example, 30% of our water from the Meuse at Tailfer,” he says. “It is warmer than usual. We then redistribute it to Brussels, Wallonia, and Flanders, where it will influence the temperature of the domestic water that comes out of your taps.”
Why the Water Warms Up
The warming happens at multiple stages. Underground water sources remain cooler and more stable, but surface water—like the Meuse—absorbs the heat of the summer sun. Additionally, the water warms as it travels through pipes in the public network and, more significantly, within buildings themselves.
“Our pipes are well insulated and buried quite deeply,” Chauveheid notes, “but it is true that if the soil heats up under the asphalt or under the sidewalks, the water risks gaining a few degrees too. But I am convinced that it is mainly in homes that the warming occurs.” Poorly insulated conduits in basements and small-diameter pipes exposed to ambient heat all contribute to raising the water’s temperature before it reaches the tap.
Is Tepid Tap Water Safe to Drink?
The question on many minds is whether this warmer water is still safe to consume. Dr. Carole Schirvel, an infection prevention physician at Cliniques universitaires St-Luc, offers reassurance while noting important caveats.
“From a general point of view, tap water remains potable,” she says. “Both the Société wallonne des eaux (SWDE) and Vivaqua carry out very regular microbiological analyses, so it is monitored.” However, she warns that warmer water can encourage bacterial growth: “The fact that the water is warmer than usual can indeed lead to the proliferation of bacteria that begin to develop beyond a threshold of 25 degrees.”
Legionella, a bacterium that can cause respiratory infections, begins to reproduce above 25 degrees Celsius. Other bacteria could potentially cause gastroenteritis. The risk is primarily for vulnerable populations—the elderly, infants, and those with compromised immune systems. For healthy individuals, drinking warmer water poses no significant health concern.
Vivaqua has responded to the heat by increasing chlorine doses as a precautionary measure. “Since bacteria like heat, we reinforce our vigilance when it is very hot,” Chauveheid explains. “The chlorine doses are increased, while ensuring we do not alter the taste of the water.”
Practical Advice for Hot Weather
Experts recommend several simple practices during heatwaves. Let the water run for a few seconds before drinking to flush out the tepid water sitting in the pipes. Fill a carafe with tap water and refrigerate it for a few hours—the cool temperature helps inhibit bacterial growth. Avoid drinking hot water from showers, and don’t drink water that has heated up during a car journey. If returning from a trip, run the water for a few minutes before consuming it.
A Summer of Records
This phenomenon is unfolding against the backdrop of an extraordinary summer. Belgium is officially experiencing its second heatwave of 2026, which began on July 28, with temperatures regularly exceeding 30 degrees Celsius. Pascal Mormal, meteorologist at the Royal Meteorological Institute (IRM), predicts this will be “certainly the hottest summer in history,” with temperatures expected to reach 34-35 degrees in August.
The drought is equally severe. According to RTBF, 80% of Flemish groundwater measurement stations now show low to very low levels, up from 50% in June. July precipitation in Uccle was just 10.6 mm—only 14% of the seasonal norm. The drought code is orange in Flanders, with restrictions on water extraction and navigation.
VRT NWS reports that the Meuse river’s flow rate is a major concern for water production at the Tailfer site, while Brussels maintains its yellow drought alert. The situation is expected to worsen, with the IRM warning that extreme drought will spread across the entire country within ten days.
Looking Ahead
Mormal’s assessment is sobering: “We have the impression of being ahead of all the most pessimistic scenarios. So yes, we will have to find solutions, but they are more of the order of adaptation.” Aurore Degré, professor of hydrology at Gembloux Agro-Bio Tech, emphasizes that drought is an insidious phenomenon with far-reaching consequences—potentially affecting nuclear power station cooling, industrial operations, and even data centers.
Vivaqua is already planning for a warmer future. “We are aware that water supply sources may become scarcer,” Chauveheid says, “and we are currently studying the possibility of finding new ones or even restarting old ones.” For Belgians, the immediate takeaway is simple: the water is safe, but letting it run briefly and refrigerating it before drinking are wise habits in a warming climate.