Why rainwater management matters

Contaminated ditch. Outi Laatikainen.

We´ve got plenty of super-good fresh water available all the time here in Finland. And rain comes ones in a while and that´s about it, right? How should we think about rainwater management as a part of circular economy concept in this kind of surroundings? Is it a thing that needs to be taken care of in areas with severe droughts and water availability problems? Or should we understand something about it also up here?

Whilst we certainly are the lucky ones with superb water resources, there are couple of points, which might be worth paying more attention in order to secure this wonderful resource also in the future.

Finland is a sparsely populated country, but still in the city areas there are remarkable amount of various harmful contaminants leached from the streets when rain comes and runoff water flushes the streets (1). And in more densely populated areas the absolute and relational amount of contaminants are of course bigger. There are eg. heavy metals, which are known to harm the ecosystem very strongly. Runoff water is the most significant single carrier for microplastics and as a topic the role of microplastics is attracting more and more attention in today´s research world. At European level EU has established a plastics strategy on January 2018 in order to pave the way for sustainability in plastics use in various sectors (2). In Finland UEF et.al. are carrying out an investigation of microplastics occurrence in Finnish waterbodies, in which the preliminary results confirm the presence of these particles also in relatively sparsely populated areas. One significant source are microplastics from car tyres, which are flushed into waterbodies with runoff water (3).

All the mechanisms, with which the microplastics might affect the health of humans and ecosystems, are not fully understood yet. But what we know so far, is that many kinds of chemical, hormonal and medical residues stick very easily on these tiny plastic particles. And that´s the way these residues get into living creatures, including us humans. Also, the plastic itself operates in living organisms as a xenoestrogene, a “fake female hormone”, which is already seen nowadays with increasing hormonal imbalances. (4) (5). These imbalances have been so strong even in some European areas, that some local fish populations have turned mostly female, which of course leads to fish population degeneration. The hormonal imbalance concerning men and boys is also reported all the time more often also in European scale. The consequences might be eg. infertility or issues in body composition like “manboobs”.

The other side of the coin is money. Yes, runoff management structures are a costly investment, but it´s also a huge amount of money that´s lost today because the unwanted runoff water gets into sewage systems. According to water utility professional estimates we might say that as a European and Finnish average runoff water forms more than 50% share of the total volume in sewages. Sewages and proper waste water treatment is for sure a good way to minimize the microplastics and other contaminants but since waste water purification units are planned to treat very different kind of water matrixes, it´s also a very inefficient and costly to have this “relatively pure” water fraction  in the same system. And since the rain doesn´t usually come as a steady daily flow but as big-volume bursts, the waste water plant capasities just can´t be modified for this. Very often waste water treatment units need to let the overflowing water run with weaker or in worst case without any treatment – because there´s no way to store it.

Separate systems to manage the runoff water flows already exist and are developed though covering still only parts of European urban areas. The structures for runoff water management might be eg. building a ditch, stream or a pool with storing capacity and controlled outflow. There might be also mechanical, chemical or biological filtering applied; some plants can help to uptake the nutrients and also some contaminants. For these kind of investestments it´s always a bit tricky to  find a financial relevance, since the payback time is not so clear and public ownership usually means weak ability to make risky investments. The first admitted loans and results are just now on their way, so let´s hope this boosts the development in the future. (6)

To mention at the end, the city areas are not the only ones that matter in runoff water issues. Agricultural operations form absolutely the biggest share of al the environmental load for water reservoirs. In agriculture there are nutrients (phosphorus, ammonium) and humus/organic material we should be able to keep in fields to feed the plants, but today we are not in that state yet. And nutrients keep leaching to harm the waters and cause eutrophication. It´s a very complex field to develop the cultivation methods to manage the nutrient and water circulation better, but there are lot of innovations under development and trial all the time. Let´s just wish we are able to learn and adapt the alternative ways when the water ecosystems can still recover. (6)

KAMK University of Applied sciences and CEMIS – Center for Measurement and Information Systems are developing new monitoring and water purification solutions also for these purposes. The main fields of operations include introducing new online solutions to monitor the contaminants in water flows, sorbent material development for water filtration based on industrial side streams and development of mixed reality – assisted tools for planning the systemic solutions. Generally spoken, Finland puts a lot of effort for increasing the understanding on circular economy systems and solutions in which the management of water flows also belongs. One example of such actions is KiertotalousAMK – Circular Economy Competence to Universities of Applied Sciences -project. The project in which KAMK also participates, is funded by the Ministry of Education and Culture and aims to increase, co-create and share expertise within Finnish Universities of Applied Sciences in various circular economy cases.

Teksti ja kuva:
Erityisasiantuntija Outi Laatikainen
Kajaanin ammattikorkeakoulu




Korkealaakso et. al 2016. Urban needs and best practices for enhanced stormwater management and quality – State-of-the-art. https://www.vtt.fi/sites/stormfilter/Documents/D1.1_SOTA_Stormwater%20quality%20management.pdf


European plastics strategy:



Koistinen A 2018: Microplastics in lake Kallavesi in Finland: Analysis of size distribution and sources.



Science of The Total Environment. Volume 493, 15 September 2014.



Toxicology – new aspects to this scientific conundrum. Chapter 6: Microplastics in Aquatic environments and their toxicological implications for fish.



Water Europe technology & innovation 2016: The value of water – Multiple Waters for Multiple Purposes and Users Towards a Future-Proof Model for a European Water-Smart Society.