Hotze Karsten turns on a tap. Photos by Zuzana Ľudviková

Flushing legionella down the drain

The men who
turn on taps

Hotze Karsten turns on a tap. Photos by Zuzana Ľudviková
Every week, all week, a group of eight people travel the whole of the university. They turn on taps and let the water flow for several minutes before turning them off again. They’re not wasting water; they’re fighting legionella bacteria.
13 September om 16:01 uur.
Laatst gewijzigd op 26 September 2022
om 12:04 uur.
September 13 at 16:01 PM.
Last modified on September 26, 2022
at 12:04 PM.
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Door Christien Boomsma

13 September om 16:01 uur.
Laatst gewijzigd op 26 September 2022
om 12:04 uur.
Avatar photo

By Christien Boomsma

September 13 at 16:01 PM.
Last modified on September 26, 2022
at 12:04 PM.
Avatar photo

Christien Boomsma

Achtergrondcoördinator en wetenschapsredacteur Volledig bio »
Background coordinator and science editor Full bio »

Hotze Karsten is no longer surprised when someone turns off a tap he just turned on. For his work in either the showers at the sports centre, one of the pantries at the Linnaeusborg, or the toilets at the Bernoulliborg, he turns on taps one by one. It’s happened more than once that a staff member walked in behind him to quickly turn the taps off again, causing him to start the whole process over again.

‘People are astonished to see me do my thing’, he says. ‘Especially when it’s really dry outside.’

‘Some people get really upset’, adds Jan Lomulder, who is still in training. ‘But one thing I’ve learned is that you shouldn’t debate them.’

‘One thing that comes in handy in this line of work’, says their co-worker Joop van der Vlugt, ‘is people skills. You have to be verbally strong.’

One thousand taps

Karsten, Lomulder, and Van der Vlugt are three of eight employees who, under the authority of water treatment company Normec Kalsbeek, regularly run the faucets at sixty-four UG locations. Working two days a week, they closely monitor a thousand taps. This means they run the taps at hundreds of showers, toilets, kitchens, sinks, eyewash stations, and boilers everywhere at the university. 

Their job gets even more intense during the holidays: that’s when they have to flush all taps. It takes them three days in the city centre and three days at Zernike. They also measure the water temperature, and twice a year, they take samples to ensure nothing’s going wrong. 

Some people get really upset

The main thing they check for is whether the legionella bacteria has found its way into the pipes. This is a bacterium that, when breathed in, can lead to flu-like symptoms. In some cases, it can lead to a fatal case of pneumonia. 

‘This bacterium thrives in stagnant water that’s between 25 and 50 degrees Celsius, Mariët Tuitman with Normec Kalsbeek explains. ‘This leads to a biofilm on the water, just like you’d get on the bottom of a pool if you don’t use chlorine or a filter.’ The legionella bacteria feed on this biofilm.

They’re not always visible, and as long as the number of bacteria stays below the one hundred ‘colony-forming units’ per litre, everything’s fine. 

On top of that, not all legionella bacteria make people sick. But when a colony does settle in the pipes, it can use those to spread to showers and other places where water sprays and that could make people ill. 

Closed buildings

Ten years ago, there was a serious case of contamination at the dentistry department at the Antonius Deusinglaan. The university and the UMCG were forced to immediately close down three buildings. The university cleaned the pipes, replaced supply lines, and installed special filters, but the contamination kept coming back. After nearly a year of investigating, the culprit was found: the taps at the dental chairs. 

The bacteria can grow just as well at the modern Bernoulliborg

No one at the university is keen to repeat this incident, which means these days, the pipes and taps are thoroughly checked. Initially, the faculties were in charge of this, but in 2021, the work was outsourced to Normec Kalsbeek. That’s why the offices and faraway corners of the UG that used to be skipped now get weekly visits from the ‘tap flusher’. 

These flushers are either people in participation jobs at the UG or staff from Normec Kalsbeek’s senior citizen pool. Lomulder, for example, was unable to continue his job in production after surgery damaged the nerves in his hands and feet. He hopes to get back to work as a tap flusher. Karsten and Van der Vlugt are both done with their careers. The former worked as a nurse in the emergency department, and the latter was a driver at youth care institute Het Poortje.

Jan Lomulder, Hotze Karsten and Joop van der Vlugt (first photo left to right) at work. 

Farthest corners

So why did they take this job? ‘I have great colleagues. It’s also just a fun job’, says Van der Vlugt. ‘I could take on advisory work, but then I’d be home alone at my desk.’ 

Another bonus is the exercise that comes with the job. The trio walk to the farthest corners of Nijenborgh, visit every shower and boiler room at the Sports centre or the KVI-Cart. Along the way, they meet dozens of different people ranging from professors to receptionists, from security officers to students.

‘Take the hockey club, for example’, says Van der Vlugt. ‘There’s still a plaque on the wall with my name on it, because I used to be president. It’s a great way to remember the past.’

At the Forward football club, they often find a huge mess and their feet tend to stick to the floor because of all the spilled beer. They’ve seen pools of vomit on the floor, and even on the couch. ‘One time you threw cat litter on it, remember?’ Van der Vlugt addresses Karsten with a snicker.

‘It’s kind of amazing’, says Lomulder, ‘to think that these are the people who’ll be leading the country one day.’

Positive samples

But let’s not forget that their work is very useful. In 2021, when very few of the buildings were in use, the legionella bacterium was found in no fewer than eighteen of the sixty-four UG locations. 17 percent of samples tested positive. Now that people have returned to the buildings, the bacterium was found at thirteen locations – 14 percent.  

If something goes wrong, it’ll only cost more time and money

Legionella contaminations can happen anywhere. In some buildings, it’s because of the complicated infrastructure: Nijenborgh 4 has an extensive network of forking pipes, says Rob ten Wolde, project leader at the university services department. ‘But modern buildings like the Bernoulliborg or Linnaeusborg are just as much at risk of growing a bacteria colony.’ All the bacteria need is for the flushers to miss a single kitchen at the end of a water pipe. 

Sometimes, running the tap a bit more after a contamination is sufficient. Other times, the tap or shower head needs a special filter to block the bacterium. In severe cases, a chemical cleaning might be necessary, or the bacteria get killed off using copper or silver ionisation. In the worst-case scenario, like at the dentistry department, pipes need to be replaced. The dental chairs were also equipped with Ecapro, which electrolyses water and salt to create a biodegradable disinfectant.

Conserving water

But it’s still a shame that thousands of litres of water are flushed down the drain each week, especially now that we’re trying to curb the use of water. Isn’t there some other solution?

Ten Wolde shakes his head. ‘If we don’t do this,’ he says, ‘and something goes wrong, it’ll only cost us more time and money.’ Besides, the university is conserving water in so many other ways. They’ve installed motion sensors in the bathrooms at the Aletta Jacobs hall and push buttons in the Sports centre’s showers. ‘The UG as a whole uses much less water than other universities’, he says. ‘They also intend to reduce this use by another 10 percent.’

However, normal UG employees won’t notice any of this. That means that Karsten, Lomulder, and Van der Vlugt will have to keep explaining what they’re doing. Karsten chuckles. ‘Just tell them how often we still find legionella. They’ll understand.’

What is legionella?

Legionella is a bacterium that thrives in stagnant water at a temperature between 25 and 50 degrees Celsius. If that water ends up in the air as aerosols, very small droplets, and you breathe them in, you can get sick.

You’ll experience flu-like symptoms: a fever, headache, and coughing. However, some people get seriously ill. They get a severe headache and muscle aches, a high fever, and pneumonia. This is also known as Legionnaires’ disease, and it can be fatal. The disease can be treated with antibiotics, though. 

Do all taps have to be flushed?

No. Taps that are in regular use do not need to be flushed. The water in those pipes changes often enough, which means the bacteria can’t settle. But during the summer and Christmas holidays, when most people have left the buildings, the taps get flushed, just to be sure.

We regularly use our taps. Why do ours still need to get flushed?

Many people use taps for as little time as possible, to save water. But if you only use a little water, the pipes don’t get flushed out sufficiently, and the legionella bacteria can still grow there.