Key take-aways

  • Unaccounted sewage water leads to higher water treatment costs

  • We’ve created a more convenient, user-friendly analysis solution

  • We’re continually developing this solution for a more insightful future

Unaccounted sewage water costs companies

Unaccounted sewage water shouldn’t be in the sewage system in theory, but in practice, surface, drainage, and ground water often enters systems via leaking sewer pipes – and this can even double the volume of waste water flowing to a treatment plant on dry days. 

This is a problem because additional unexpected water in the system means pumping stations use more energy and the need for additional purification can increase, leading to higher costs. In addition, clean ground, drainage, and surface water draining into the sewage system can contribute to dehydration.

The difference between what happens in theory and practice can be expressed in pollution units. Discrepancy is the difference between the predicted pollution load and the load that’s actually measured.

Discrepancy can be up to 20 or 30 per cent, meaning treatment costs aren’t fairly distributed among the ‘polluters’. For example, a company can discharge far more pollution units than it pays in treatment charges.

A user-friendly and automated solution

Three years ago, an initial Excel calculation tool was created that allowed water boards to calculate sewage sludge and discrepancies unequivocally and uniformly. The tool gave good results but required a lot of labour-intensive manual work.

We needed a new, more convenient, user-friendly, and automated tool. Through DEEP: The Data Science and Engineering Expert Program – a collaboration between Het Waterschapshuis and Royal HaskoningDHV - we developed an initial prototype using Het Waterschapshuis’ Microsoft Azure Cloud platform.

An interactive platform for insight

The new tool combines multiple online data sources such as the Weather Information Water Management for precipitation data and Z-info – a central system that measures wastewater supply to purification plants. 

Water boards can also use an interactive platform to collate both theoretical and practical values to perform calculations for unaccounted sewage water and discrepancies.

The new online tool is available since early 2022.

Continuous development creating further value

The tool will undergo continuous development and refinement after it’s been fully deployed, coordinated with municipalities and water boards.

The development will look to: expand analysis of unaccounted sewage water, add analysis of rainwater discharge, and integrate with the BGT intake tool and table.

These improvements will enable water boards to gain better and faster insight into their performance, highlighting the value of data-driven work in water management.