I amsterdam - Canal Sanitation

Long ago
For centuries, Amsterdam's canals had a less pleasant function: the busy waterways through the city also served as open sewers. Houses and factories discharged their waste, while household refuse, offal, rubbish and market trash were thrown in the canals. This system left the city with a rather unpleasant stench. In fact, in 1838, the German pastor F.W. Dethmar once turned walked through the city pinching his nose, writing later in his diary: ‘The stranger who views the city wrapped in a blue mist, and in the autumn breathes its unpleasant stench, will conclude with no second thoughts, that it is the least healthy place in the world’. These days the canals no longer pollute the air with foul smells, as they are cleaned and sanitised nightly.

Regular sanitation
Anyone walking along the canals at night might be lucky enough to see a lesser-known aspect of Amsterdam's relationship with water. About 40 sluices in the centre close between 19:00 and 20:30 every evening so that the water in the canals can be sanitised and cleaned. From places such as the AmstelRiver by the Carré Theatre, or the Haarlem Sluice in the Singel, one will find workers turning an enormous wooden wheel to close the sluice gates. An mage-sized pumping station on the eastern island of Zeeburg begins pumping circa 600,000 cubic metres of water from the IJsselmeer into Amsterdam's canals. To allow the water to flow through rapidly, between two and four sluices on the West side of the city are left open. The water from the canals flow through these sluices into the River IJ (the section of the harbour between the IJsselmeer and the North­-Sea Canal) to find its way to the sea via the North-SeaCanal. This guarantees that the entire water content of the city canals is completely refreshed every three days.

Pure enjoyment
Draining the canals takes place seven days a week, 52 weeks in the year and is only ceased occasionally when temperatures drop low enough in the winter for the water to freeze. It takes about three days of severe frost for the ice layers on the canals to be thick enough for people to skate on them – and they do. There is nothing lovelier than the crisp sound of blades cutting across a silver canal in the light of the moon. While this only happens every decade or so, it is still a treasured site to see.

Water levels
The so-called City Water Department, responsible for draining the canals, also keeps a close eye on the water level. As Amsterdam is linked to the sea via the North-SeaCanal, levels can start to increase during a lengthy westerly storm. Heavy rain in the Southern polders - which dispose of their excess water in Amsterdam's water - can also raise the canal levels. Thanks to the pumping station in Zeeburg, floods are avoided and the water levels are maintained. The refreshing process is then reversed and the water is pumped out of the city and into the IJsselmeer. For a good look at the water levels of the city, head over to the City Hall on the Amstel. By the north-eastern entrance hallway, you will find larger-than life hydrometers based on the Normal Amsterdam Level system.

The world below
There is life existing underwater in these canals. Various fish, including eels, make their home out of these waterways. Amsterdam’s canals sometimes take on a greenish hue due to algae. And the canals may look shallower than their official average of three meters. It is said that one should deduct one meter for the mud and another for all the discarded and lost bicycles which have found their way into the canals over the years. Curious about what a canal looks like from underwater? The Artis aquarium provides a great look at life underwater – fish and bicycles included!