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How WVRB ensures safe drinking water for 250’000 people

Interview with Bruno Burkhalter, process engineer at Wasserverbund Region Bern AG

The Wasserverbund Region Bern AG (WVRB) delivers drinking water to a quarter of a million people. In his role as Process Engineer, Bruno Burkhalter, is responsible to ensure its quality. From raw water extraction to transport and eventually disinfection, he keeps an eye on all steps to ensure that only the purest water reaches the Bernese network.

We wanted to learn how he manages this task and met him for an interview at the Belpau pumping station – one of three groundwater stations where WVRB uses BactoSense to reliably monitor the microbiology of the drinking water at all times.

Dear Mr. Burkhalter, how does it feel to be responsible for the drinking water and thus the health of 250’000 people?

It is certainly a big responsibility. We have the resources and do not shy away from the costs that are necessary to ensure a high quality. We are always striving to keep the water safe.

You operate a complex system with water catchments, reservoirs and an extensive network of transport pipelines. How do you ensure that everything works smoothly and safely?

We have many process controls that make our daily life easier. Our two main pumping stations (Belpau and Schönau) operate according to an energy plan. The amount of water to fill the reservoirs is ordered the day before and distributed to the pumping stations.

For the peripheral reservoirs and pumping stations, we work with a target curve that defines the number of pumps needed to fill the reservoirs. We also have various alarms for flow rate and quality data. There is always at least one on-call person who reacts according to the priority of the alarm. Response times range from "immediately", "6-10 a.m. the next day" to "no immediate response required".

WVRB Grundwasserbrunnen
Overview of the WVRB network with the two groundwater wells that are monitored with BactoSense. Water is almost exclusively groundwater from the Emmental region (Aeschau) and the Aaretal (Belpau, Kiesen, Wehrliau). Image source: WVRB

Where do you think the greatest health risks lie?

In our water supply system, bacterial contamination would certainly have the greatest impact. Other significant dangers are oil and chemical spills due to the proximity to the river. In Kiesen there is a risk of substances getting into the water because the Aare river, feeding the groundwater, is crossed by a railway and a motorway, where hazardous substances are transported.

Where do you see the biggest challenges in your area of responsibility?

It is to interpret bad results correctly and to make the right decisions for the health of consumers. For example, if a limit value of the Drinking Water Ordinance (Trinkwasserverordnung - TBDV) is exceeded at one point, a measure must be initiated. This could mean that follow-up checks have to be carried out at other points. It is important to take an overall view and to act fast and appropriately.

Years ago there was a manure accident in the protection zone, which also affected the stream near the catchment area. By chance, a sample was taken at that time, in which E.Coli was detected. The water was no longer used and emergency chlorination was initiated. The next bacteriological sample analysed was good again.

What are your critical control points and what is measured there?

In Bern, the critical control points according to HACCP only concern disinfection (detected amount of energy in UV or concentration in chlorine dosing). This is because a critical control point is a step where a possible risk can be reduced to an acceptable risk.

The most important other control points are protection zones, measuring points during withdrawal, reservoirs and laboratory analyses from the network. Various methods are used for this purpose:

  • Measuring panels with temperature, pH, conductivity, redox, turbidity, spectral absorption coefficient (SAC) and partly oxygen and TCC/HNAP (flow cytometry)

  • Laboratory analyses: catchment to reservoir and transport pipelines between communes. The municipal networks are monitored by the local authorities themselves.

WVRB has been using BactoSense for two years. Where is it installed and how do you benefit from it?

BactoSense was first installed at the main pumping station, where water is mixed and treated. Due to the routing of the pipes and pump downtimes, there was a lot of bacterial growth. To improve this measuring arrangement, BactoSense was moved to the groundwater well – providing considerable insights, especially due to the floods last year. Generally, we found good stability in the well.

The results provided by BactoSense helped us to conclude that we are well positioned with the SAC measurement for our groundwater wells. However, since the BactoSense measures much more sensitively, it makes sense to use it in the transport system. We still suspect considerable dangers there and hope to detect small deviations faster and better.

What do you expect from BactoSense in the future?

We have already tried multi-probe measurements with the standard method that did not deliver the desired results. We hope that the direct measurement principle of the BactoSense will provide us with more information about the influence of contamination and better control.

For example, contamination in the transport network could be detected by BactoSense and the effect then observed in the secondary network. EWB takes weekly laboratory samples, plating and total cell count. Knowing how microbiological contamination affects the distribution network, we could then also better determine the reaction.

From your experience, what are the advantages of online flow cytometry compared to the classical plating method?

The fast availability of the results and the online connection facilitate the immediate detection of dangers, meaning that measures can be taken in a more specific manner. Compared to the past, we are more sensitive to microbiological contamination.

If the total cell count (TCC) value is high, we know that there may be microbiological contamination which could not have been detected with the plating method. This helps us to decide how quickly to react in the event of an alarm from the chlorine dioxide system.

“The direct availability of the microbiological measurement has a direct influence on how to react. This is because you get a result immediately and not three days later.”

Where would you like to have better control of water quality?

The current approach focuses on control at the catchment and distribution points. Part of the transportation network is still quite unknown and it would be nice if this could be monitored better. Measurement at the endpoint, the tap, would be desirable – if homeowners also had a self-monitoring facility. A few years ago, a property manager called me because her maintenance staff had legionellosis and she thought the water we provided might have been bad. However, there was a problem with the plumbing of the house.

How do you think water quality management will change in the next 20 years?

We will be confronted with more and more micropollutants. Not because they are new, but because we can detect them more and more accurately. Depending on which method is used, we are already in the nanoscale range. This will certainly change water management and may lead to groundwater treatment in several stages or to the development of a certain acceptance.

Key figures on the WVRB

Water origin: around 99.5% groundwater and 0.5% spring water

Production capacity: around 111,000 litres per minute

Average daily production: 60-65'000 m³

Number of inhabitants supplied: approx. 250,000

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