Beatrice is a native Melbournian who moved to the Netherlands in 2009. With a background in independ...
Are Amsterdam’s canals clean enough to swim in?04 August 2014, by Beatrice Clarke
On those rare summer days when the temperature creeps into the high 20s and the sun shines warmly down, glittering canal water can look terribly inviting. Wouldn’t you love to slip into the cool depths and go for a swim? Often the thought of unknown bacteria and submerged bikes holds us back, who knows what’s in the water!
This article provides some insights into one of life’s great mysteries: is it safe to swim in Dutch waterways?
Amsterdam’s canals never cleaner
An investigation by pop science website Kennislink revealed some positive developments for canals in the nation’s capital: water quality has never been so good! Never in 400 years have Amsterdam’s canals been so clean! So much so that water manager Waternet has stopped regularly flushing out the canals. Despite the good news however, canal water quality can still be further improved.
Historically canals used as dumps
For hundreds of years open water in Amsterdam was treated as a garbage dump and sewer. People dumped rubbish straight into canals and sewerage flowed in via pipes and gutters. The situation was especially bad during periods when the city grew quickly, such as at the end of the 19th century. Amsterdam’s canals remained polluted well into the 20th century, even after the introduction of sewers and rubbish collection services.
Canal pollution today
Thanks to new measures introduced by Waternet, there has been a rapid improvement in canal water quality in recent years.
At present the main polluting factor of Amsterdam’s canals is the "overflow" of sewerage during heavy rains. Waternet spokesperson Maarten Ouboter explains that during and after downpours rainwater flows into the sewer system causing the contents to overflow at hundreds of points around the city. This issue usually occurs less than 10 times a year, with pollution levels usually subsiding after around three days via dilution and biodegradation.
Waternet is working to bring sewerage overflow under control by installing big underground tanks. These containers can temporarily store large quantities of rainwater that would otherwise interfere with the sewerage system.
There are also around 800 (out of a total 2.800) houseboats in Amsterdam whose waste water still goes directly into the canals. Within a few years all houseboats and vessels must be connected to the sewer.
The word from Waternet
The official line from Waternet is that swimming in Amsterdam’s canals is not permitted as water quality is not clean enough and also because the canals are classified as boating ways (vaarwegen). This judgement is still current for summer 2016.
However, Waternet is aiming for bathing-safe quality canal water. This will only be achieved once all houseboats are connected to the sewerage system, roughly by 2017-2018. The water manager also warns about hazards like rubbish and submerged debris, particularly bicycles, which they regularly haul out of canals - at a rate of 50 bikes per day!
The Amsterdam City Swim
The Amsterdam City Swim, launched in 2012, demonstrates the potential of clean canals. That year then-Princess Maxima took the plunge (and survived), swimming two kilometers to raise money for charity.
Waternet video (in Dutch) about historic improvements in Amsterdam's canal water quality.
In the lead up to the swim each year, Waternet closely monitors canal water quality for the presence of two "guide" bacterias: E. coli and enterococcus. If there has not been any heavy rain (and thus no sewerage overflow) prior to the analysis, then the water quality will meet swimming standards.
Zwemwater: the app
Until Amsterdam’s canals are pristine perhaps it is wiser to visit one of the many official outdoor swimming spots around the Netherlands. Zwemwater, an app and website, lists more than 800 swimming locations around the country, providing up-to-date information about swimming water quality.
The app features an interactive map and rates locations using three categories of water quality: goed (good), waarschuwing (warning) and zwemverbod/negatief zwemadvies (swimming ban/negative swimming advice).
Water quality checks
The swimming advice is based on water quality checks conducted by the governmental department Rijkswaterstaat, the provinces, area services and water boards. Zwemwater gathers the data from these separate sources and displays it on the app and website.
The app also mentions the dates of the most recent and upcoming water quality checks, and provides information on facilities available at each location. Water quality is only measured at outdoor swimming spots during official bathing season (May 1st to October 1st).
In true Dutch fashion the responsibility of choosing to swim or not lies with the individual. For locations with a warning, meaning that swimming there can be hazardous for health, people are permitted to swim, but must assess themselves if there is a health risk (for example by checking for algal bloom). On these occasions young children and elderly people, who are the most vulnerable, are advised to find a different spot to swim.
Swimming in the future
Perhaps in a few years certain canals in Amsterdam will start appearing on the Zwemwater app. Then everyone will be able to enjoy a dip in Amsterdam waters, only mind the rusty bikes!