If you thought Stockholm’s most exciting attractions were the old town, museums, and IKEA, I hate to disappoint (or maybe delight) you – the real marvel lies underground, in the form of one of the world’s most spectacular wastewater treatment facilities.
When the city began expanding rapidly in the second half of the 19th century, the quality of Lake Mälaren – Stockholm’s main water source – was seriously compromised. It didn’t take long for the residents to realize they needed a serious wastewater solution to protect public health, and that’s when Henriksdal stepped onto the scene.
This engineering masterpiece was built back in the 1930s, carved directly into solid rock. But Henriksdal’s true marvel isn’t just that it’s underground – it’s how it was designed. Instead of sprawling across Stockholm’s precious surface area, the clever Swedes thought: “Why don’t we build it vertically… but downward?” And so, the facility was spread over multiple levels inside the rock – like an underground layer cake for treating wastewater.
And you know what else is brilliant? Because the basins were quite literally blasted from the rock (yes, they used explosives), they could make them much deeper than if they had been built above ground. And the best part? Instead of expensive concrete walls – they used the bare rock itself! Nature as a building material. Environmentally friendly and surprisingly cost-effective – it turned out that digging through solid rock was actually cheaper than building on the surface.
To make it even more interesting – the plant is so discreet that you could literally live above it and have no idea what’s happening beneath your feet. There are no unpleasant smells, everything is enclosed, quiet, and clean. In fact, back in the 1960s, they built the entire Henriksdalsringen residential neighborhood right on top of the facility.
As Stockholm continued to grow, so did Henriksdal. Its capacity doubled, the basins grew deeper, and by the 1990s, they decided to deepen the reservoirs even further – from five to twelve meters.
Today, Henriksdal, together with the neighboring Sickla facility, serves a staggering 800,000 people. And that’s not all – a massive expansion is currently underway under the “Stockholm Future Wastewater Treatment” project (or as I like to call it – Mission: Cleanpossible). The plan is to upgrade everything to serve up to 1.6 million people and to phase out older facilities, like the one in Bromma.
To make this happen, new underground tunnels are being built – real sewer highways. The most impressive is the Bromma tunnel – a 14-kilometer-long marvel, blasted beneath the city, under the lake, and through bedrock, all the way to the Sickla facility. What’s especially important is that these tunnels are designed to last at least 100 years.
In the end, I have to admit – this isn’t just an engineering feat. It’s a shining example of human ingenuity that enables the most efficient, quiet, and clean wastewater treatment possible.
So, next time you’re in Stockholm, strolling through the Henriksdalsringen neighborhood, remember – there’s an entire world beneath your feet, working tirelessly, day and night, to make sure everything that goes down the drain is treated in the best possible way.
And that, my friends, is what I call the magic of urban life.
