top of page

Groundwater monitoring in Iceland

Updated: Dec 5, 2023

Interview with Sigrún Tómasdóttir and Sverrir Guðmundsson

The biggest waterwork in Iceland, Veitur, has installed 5 BactoSenses in the last five years to mitigate the risk of contaminated water and improve trust in water quality and by extension public health.

In this interview, Sverrir Guðmundsson, the Research and Development Lead and Sigrún Tómasdóttir, a geologist at Veitur, tell us how implementing BactoSense helped them with research projects and to understand better and control their system. They explain how near real-time measurements with the automated flow cytometer (in normal conditions, under rain and melting events) allowed them to improve their borehole management. Sverrir and Sigrún also share their vision for the future of Veitur and water monitoring. Thanks to their experience with BactoSense, they also give practical and valuable advice to future users.

Sigrún Tómasdóttir and Sverrir Guðmundsson from Veitur in an Interview with bNovate Technologies about Groundwater monitoring in Iceland
Sigrún Tómasdóttir and Sverrir Guðmundsson from Veitur, Iceland
Dear Mrs Tómasdóttir, dear Mr Guðmundsson, you are both water professionals working in Iceland. Tell us a bit more about yourselves.

Sigrún Tómasdóttir: I am a geologist at the Research and Development Department of Reykjavik Energy, the parent company of Veitur Utilities. I work at the waterworks with Sverrir on projects related to sampling and data analysis for quality testing. We also manage issues related to water quality and water reserves. In addition, for each utility, we are establishing future vision projects considering multiple parameters, such as the development of water demand, climate change, size and location. Each utility has a different sensitivity to events and water quality. By evaluating how the parameters affect them, we can improve our planning and decision-making related to drilling, reserves or water quality.

Sverrir Guðmundsson: I am the Research and Development Lead at the Veitur Waterwork in Reykjavik. I am involved in projects focusing on the future of water production and quality. I also work on technical projects such as asset management, system planning, innovation and intelligent technology. These aspects are crucial for maintaining and improving the water distribution system.

Reykjavík water production areas where Veitur installed bNovate's BactoSense for rapid water monitoring of ground water
Iceland is a country of spectacular landscape, with volcanoes and glaciers, for example. Do you have specific factors you must consider for water production and distribution?

Sigrún Tómasdóttir: Being located on tectonic plate boundaries and having active volcanoes means that there is a lot of seismic activity. We regularly need to think about that, especially in recent years. Could an eruption happen close to our production sites? What effect could that have? Is there a risk that a large earthquake will impact our distribution system or reserves? These are not day-to-day threats but something we need to take into account.

Sverrir Guðmundsson: We operate waterworks in Reykjavik and West Iceland, and these regions are quite different. Let's take Reykjavik: it is on a Peninsula right by the Atlantic ridge, an active volcanic zone. The water pumped from the boreholes is drained through permeable Holocene lava fields and flows through long paths. It is naturally filtered to very high hygienic quality, and hence we can most often distribute it without any further chemical treatment or nutrient addition.

Veitur Utilities is Iceland's most prominent utility company, serving around half of Iceland’s population. What are the potable water regulations you must follow?

Sigrún Tómasdóttir: Every year, the health authorities take samples from all the water utilities of Veitur Utilities for microbial analysis. The frequency of the sampling depends on the population in each area. So, for example, in the capital area, health authorities take around 100 samples for microbial analysis per year from the distribution system. They also routinely analyse pH, conductivity and temperature. Health authorities then conduct a comprehensive chemical analysis of water from the waterworks in Reykjavík eight times yearly to identify all possible contaminants. This is done in our other smaller utilities once or twice a year.

Sverrir Guðmundsson: The safety indicator for microbial contamination is the culture and detection of E. coli and the total microbiome growing at 22°C. In Iceland, the regulation states that per 100 ml, no E. coli or coliform bacteria are allowed, and the tolerance for other microbes growing at 22°C is less than 100.

Installation of the first bNovate BactoSense at Veitur in Iceland in 2018, for rapid groundwater monitoring
Installation of the first BactoSense in 2018
Can you tell us about how you monitored water quality before BactoSense?

Sverrir Guðmundsson: Before implementing BactoSense in 2018, we took manual samples for plating to control the microbial quality. We discarded lower-quality water and distributed untreated potable water. This was possible in Reykjavik because we operate two production areas with a total production capacity of 2400 litres per second, which is double as much as the highest water consumption peaks we have ever observed. Back then, our production system faced two problems: on the one hand, manual bacterial plating did not allow us to monitor the water from the lower production areas in real time. There, the older, shallower boreholes are more exposed to surface contamination. Therefore, in wintertime (between October and April), we needed to take them entirely out of operation; on the other hand, we faced production restrictions in the higher area. We only have permission to produce 300 litres per second annually from deeper boreholes of higher quality because they have less exposure to surface water contamination. Higher-area boreholes alone are not enough to satisfy the whole demand.

What did BactoSense change for you, and what did you learn by using it?

Sverrir Guðmundsson: Before implementing BactoSense, we did not know how the most exposed boreholes behaved during floods. But after a sizeable thawing event in 2018, we have done two things:

1- We implemented UV disinfection as a backup for the lower areas that are more exposed.

2- We implemented direct measurement with BactoSense, which provided more information about the boreholes' behaviour.

BactoSense measures total cell count (TCC) in water. By monitoring boreholes and measuring their background values, we now know how the boreholes that we have observed behave and how sensitive they are during events. Comparing the TCC values from BactoSense with the count of cultivated bacteria, we always find a very high correlation but no uniform correlation. That relates to the complexity of microbiomes that vary between seasons, locations and even between events. What is certain is that a rise in TCC, especially a high rise, is a strong indicator of microbiome contamination. Now, we can utilise the lower areas more confidently, as we know that increased TCC values strongly indicate contamination, and we can stop using the borehole.

Sigrún Tómasdóttir: We use BactoSense manually for some of the smaller utilities by taking samples we can analyse in less than 30 minutes. For example, a few months ago, we had what appeared to be a failed sample taken during regular auditing. We were sceptical about the result because the weather conditions were frosty and calm, which makes for good water quality. Sverrir graciously went on a Friday afternoon to take a sample to measure on BactoSense and analyse it. We could compare the results to previous samples from that utility. The TCC value did not exceed our previously observed background samples. We could immediately tell the health authorities that this may have been faulty sampling and not wait three days for the plating to replicate. We could quickly assess the situation and avoid disturbing the population.

Sverrir Guðmundsson: This situation allowed us to implement a reliable flushing process before sampling for the health authorities. Now they can entirely rely on the quality of their sample collection process.

What else did you learn about the boreholes with BactoSense?

Sigrún Tómasdóttir: We've learned that the bacterial community around the wells we're utilising can be very diverse, even within the same production area. We also learned that some boreholes have orders of magnitude higher background TCC values, which doesn't mean that there's anything wrong with that water. It is simply a reflection of a very different bacterial community. We're learning a lot, and we continue to investigate. For example, we will move some of our BactoSense instruments within the areas to better understand the behaviour of single wells we have yet to monitor continuously.

Sverrir Guðmundsson: We also learned that the TCC values decay slowly before stabilising after rain or melting events. This may take up to days in Reykjavik and even weeks in some of the boreholes we have been monitoring in West Iceland. Knowing how fast the boreholes recover and stabilise after an event is critical for us.

Operator sets water quality thresholds. Without BactoSense, the threshold is set depending on time of the year. With BactoSense, high quality is defined by TCC background value within the 99% confidence interval.

The operator sets the water quality thresholds. Without BactoSense, the threshold is set depending on the time of the year. With BactoSense, high quality is defined by TCC background value within the 99% confidence interval. Everything in between is considered good quality.

You mentioned that different boreholes have different background TCC values. How did you come up with the threshold for your water quality evaluation?

Sverrir Guðmundsson: To set up thresholds for the boreholes, we measured the stable background values during favourable weather conditions and then put some 99% confidence into it. When we observe a fast-rising TCC above our threshold, we know this strongly indicates bacterial contamination. We learned this by comparing it to some cultivated samples. But if we have a high rise in TCC values, we have a strong indication of dropping quality or contamination.

Thresholds are relative to the particular borehole and its specific complex bacterial communities, varying between events, location, time of the year, etc. Indeed, we have found that during some of the events, TCC values in some boreholes exceeded the set threshold, and the water remained of good quality. Therefore, we set our thresholds iteratively. We generally put them lower than needed because we have a production capacity that exceeds two times the demand, and we can afford to be stricter.

Does BactoSense help you manage water production, and do you see a benefit?

Sigrún Tómasdóttir: We are still in the learning phase, and BactoSense helps us to mitigate the risk of contaminated water. In addition to improved public health, there is also a social impact on the population because they can trust the water quality.

Sverrir Guðmundsson: The policy of the company is to be transparent. We want to inform the people as much as possible through the media, in public venues and at conferences. We keep everything in the open. So when we claim that we have the best water in the world (smile), we know we have pristine water purified through natural processes.

Sigrún Tómasdóttir: It is a national pride that we have clean water that people rely on, and we want to maintain that. We know of our advantages with water quality compared to other countries, but we have challenges. For example, we have very permeable bedrock, which means that surface contamination, if it occurs close to our well fields, can enter the groundwater and persist for a long time. Therefore, it is essential that large water production areas were defined decades ago. Our essential task at Veitur is maintaining that legacy and the protection areas. We work hard to bring public awareness on that topic because not everyone knows where water comes from and how sensitive it can be.

In the future, can you imagine that BactoSense will replace plating?

Sverrir Guðmundsson: Definitely, yes. That's my vision for the future of Veitur Utilities: to be able to control and monitor water quality in near real-time. With BactoSense, we can always select the boreholes according to the highest quality, meaning that we will choose only the boreholes closest to the stable TCC and HAP background values.

However, the matter is not only to have a smart device like BactoSense, but also to implement better methods to control the boreholes. We need to adjust our processes and implement some changes to do that. BactoSense showed us where to look. First, we have learned that there are better ways to control the boreholes on and off than turning the boreholes on and off. Bacterial contamination dramatically increases if we shut them down and turn them back on. Instead, we need a soft speed variation to remove the bad-quality water slowly. Second, we have learned that the method used to flush the boreholes caused the flushing water to go back into the boreholes and increased bacterial contamination. So we also needed to improve the flushing techniques.

Sigrún Tómasdóttir: BactoSense can also be used for research projects, and results can be unexpected. For example, during one experiment, we artificially created precipitation near a borehole to see if it was particularly vulnerable to surface contamination. Coincidentally, we observed that when flushing the well towards the surface using a 20-meter-long pipe, the water came straight back in with a higher bacterial content.

So, you have had the instrument now for about five years. What is your advice to people who would like to adopt this technology?

Sverrir Guðmundsson: I would tell them that BactoSense is accurate and reliable. It helps us better manage risk and control the water quality of the groundwater extraction boreholes. Now, we can have a more optimal use of the water resource.

I would also tell them to think thoroughly about their end goal. We acquired BactoSense because we wanted a method to quickly determine or detect the microbiome quality. We started with one BactoSense to experiment and see how it works for us, our purpose and our wells. We did a lot of data comparisons with cultivated bacteria. We ran tests for over a year to see how the device operates under stable background conditions, like good weather, or how it responds during surface floods, rain and massive events. We learned a lot from our pilot, notably about what information we could get and how to use it.

Sigrún Tómasdóttir: On the practical side, I would tell new users that the device needs maintenance, so place it in easily accessible areas. They need to consider having a spare electrical supply because if the electricity goes out, it shuts off, and you may lose measurements.


​Population served:

165 000

Water Origin:

Groundwater extracted from boreholes drained by

permeable lava fields

​Production capacity

(annual average):

​2400 litres per second in Reykjavik

​Average daily production:

​740 L/s in Reykjavik


bottom of page