Published: 22. Jun 2021

From groundwater to tap water


You might not think about it when you open your tap and have a glass of water. How did our water get so clean? Operations assistant, Anders Sørensen has the answer. He makes sure that the citizens of Aarhus Municipality have clean tap water.

A heavy smell of rotten egg hit the nostrils as Anders Sørensen opens the door to the water facility’s oxidation chamber. The smell is heavy in the air inside the grey concrete walls. The gas in the air is the result of an oxidation process where air bobbles of 2-3 millimetres is sent through the water to extract iron, hydrogen sulphide, and methane. Therefore, the smell is a natural part of the process when ground water becomes tap water at Kastedværket north of Aarhus.

Anders Sørensen is an operating assistant at Aarhus Vand. He has the responsibility for ensuring that Kastedværket can deliver clean tap water. At least once a month, he must go through the water board and the 16 drillings where the ground water is pumped up. Today, he starts the day at a water drilling a few hundred meters from the water board.

Inspections of drillings

This water drilling is at a gravel road. A little square woodshed is built around the actual drilling, where the ground water is pumped up. An electrical fence makes sure that Anders does not get a visit from the nearby horses when he works at the site. The display at the water pump shows 0.0. There is no need for the pump to be running all the time.

“The older the water is when we pump it up, the better”, Anders Sørensen tells as his phone rings.

With a quick touch on his earpiece, Anders answers the call. It is the co-worker Jesper Hansen which is helping with today’s inspection of the water board.

“Hang on for 2 seconds, then you can test out the security alarm on this drill site.”, Anders says and points to the alarm on the inside of the woodshed.

A responsible job

The citizens of Aarhus Municipality use approximately 120 litres of water per person a day. Kastedværket delivers water to about one fourth of the inhabitants of Aarhus in the middle and northern part of the municipality. Therefore, it is an important and responsible job that Anders does, when he ensures the operation at the water board.

If we cannot document the security of the tap water to be 100 %, the water supply stops until we can ensure that the water is entirely clean.
- Anders Sørensen, driftassistent Aarhus Vand

Therefore, hygiene has always been of high priority, which has not become less during the Covid-19 pandemic. Face masks, latex gloves, sanitizer, and blue slippers on the shoes is a part of the daily routine.

Back at the water board it is time to have a closer look at the other part of the ground waters journey to become tap water. This part consists of several reservoirs where the water seeps through a sand filter, which looks like a big sandpit. Exactly like at the oxidations process, gasses, which smell sets deep in the nostrils, are extracted. However, this does not bother Anders. He believes that he, through his 8 years as operating assistant, has gotten used to the smell.

During the review of the pipes, pumps, and sensors, Jesper Hansen enters the room and is met by Anders with a Covid-19 friendly greeting. “Jesper, do you think it smells in here?”, Anders shouts to make himself heard above the constant noise from the pumps.

“Yes, I can easily sense the farting-smell in the room,” Jesper responds.

Critical situations

Today, there are no critical task at the water board. However, not all days are as easily predictable as an operating assistant at the water board. In cases of incidental reports or urgent breakages on the water pipes or pumps, the earpiece rings non-stop. Then, Anders knows he must hurry.

Driftbillede 2

“The last time we had a breakage, I ended up working for 17 hours. It is always critical, when severe breakages happen, and I cannot go home until the problem is solved,” Anders tells. “But it is also the urgent alarms, that make the job exciting. This is where we need to be ready and work fast,” Jesper supplements.

Fortunately, it is not every day the alarm goes off. Besides the always critical breakages on pipes or pumps, the alarm can also be activated in other ways. Anders has both experienced cars and trucks setting off the alarm by driving into the drilling houses.

“One day a hunter had sent a rifle shot directly through the wooden wall and into the electrical board. At that moment, I was happy not to be at the drill site,” Anders tells.

The day’s last item is an inspection of the six cylinder-shaped water containers. They are 45 metres long and has a diameter of 3 metres. It can all be monitored from a large concrete room, which is situated underground. A constant noise from the large pumps is thrown around the room by the solid concrete walls. After it has been through the oxidation- and filtration processes, the clean water is stored here until it is sent towards the city of Aarhus by the powerful pumps.

All sensors are working according to the plan and the alarms blares loudly when Anders knowingly sets them off. After all, he is the one who gets the alarm call.

The day’s inspection of the water board is thereby over. Anders jumps into his mint green van and heads towards a lengthened weekend.