Case Study: Kristinehamn Municipality and WaStop® in Stormwater Networks

Background

Kristinehamn is a municipality in Värmland County, Sweden, with a population of around 24,000. Like many municipalities across northern Europe, Kristinehamn's Water and Wastewater department manages an extensive network of sanitary sewer and stormwater pipes serving both urban and rural areas — infrastructure that faces increasing pressure from ageing assets, urbanisation and more frequent high-intensity rainfall events.

The challenge the department faced was not unusual: a number of locations in the network were experiencing backflow incidents, where water surcharging in the sewer system reversed flow at low-lying connection points, causing localised flooding. Traditional interventions — penstock valves, manual overflows and pump adjustments — required regular operator attention and were not providing reliable protection.

Why They Chose WaStop®

Kristinehamn's Water and Wastewater team had been evaluating alternatives to their existing backflow management approach when the WaStop® Inline Check Valve came to their attention. The key requirements were:

• Passive, automatic operation — a solution that would work reliably without requiring manual intervention or a power connection at the installation point
• Compatibility with existing pipe infrastructure — they needed a product that could be installed into the existing pipe network without requiring large-scale civil works or pipe replacement
• Low ongoing maintenance — the department needed to reduce the operational burden associated with managing multiple problem sites across the network
• Proven performance in both sanitary sewer and stormwater applications — the problem sites spanned both network types, so a single product solution was strongly preferred

The WaStop® met all four requirements. Its flexible sleeve design operates entirely passively; it installs inside the existing pipe barrel via standard access chambers; it has no moving parts requiring scheduled maintenance; and it is certified for use in both foul and surface water applications.

Installation

WaStop® valves were installed at several identified problem locations across Kristinehamn's network, covering both sanitary sewer connections and stormwater outfall points. In each case, installation was completed through existing access chambers, without excavation or disruption to the surrounding road or landscape.

The installation process at each site was completed in a single working day. No specialist plant or large crews were required — the compact installation equipment and straightforward process meant that the department's own teams could manage the work with standard drainage maintenance resources.

Results

Following installation, Kristinehamn's Water and Wastewater department reported no further backflow incidents at the treated locations. The passive, automatic operation of the WaStop® valves meant that protection was in place immediately after installation, without any configuration, commissioning or ongoing adjustment.

The department's assessment of the product was direct and practical: "Easy to install, reliable, and a high quality product."

Significantly, the reduction in manual intervention requirements freed up operator time that had previously been absorbed by monitoring and responding to problem sites — a benefit that compounds over time as the number of treated locations grows.

Lessons for UK and Irish Drainage Authorities

The Kristinehamn case illustrates several principles that are equally applicable to drainage network management in the UK and Ireland:

• Targeted intervention outperforms reactive management — identifying specific backflow risk locations and installing passive protection is more cost-effective than continued manual monitoring and incident response
• Installation simplicity matters at scale — when protecting multiple locations across a network, the ability to install quickly through existing access infrastructure significantly reduces programme time and cost
• Passive solutions reduce long-term operational burden — valves that require no power, no control systems and minimal maintenance are easier to manage across a large asset base and easier to include in drainage management plans

Could WaStop® Solve a Similar Problem in Your Network?

NordSeal supplies the complete Wapro product range — including WaStop® Inline Check Valves, WaFlap™ flap valves, WaGate® gate valves and WaReg® flow regulators — to local authorities, drainage contractors and water companies across the UK and Ireland.

If you have locations in your network experiencing backflow incidents, or if you are planning a proactive programme of backflow risk reduction, our technical team is available to review your requirements and recommend the most appropriate solution.

View the full WaStop® Inline Check Valve range, explore WaFlap™ flap valves and WaReg® flow regulators for complementary network applications — or contact our team to discuss your network's requirements.