Friday 13th November, 2020 Water Blog

What are Surfactants?

In chemistry terms, surfactants are compounds that lower the surface tension (or interfacial tension) between two liquids, between a gas and a liquid, or between a liquid and a solid. In basic terms, surfactants have a special ability to dissolve fat/oil while at the same time being water soluble. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, or dispersants [1]. The most familiar use for surfactants is in the manufacture of soaps, toilets, laundry detergents, dishwashing liquids and shampoos [2].

So, where does the washing up liquid, washing powder, detergent end up? The treated clean drinkable water that enters your house is used by a person for showering, cleaning and flushing the toilet and goes down the drain. Once that happens we don’t really need to think of it again but it’s so important we understand where it goes and the impact it has on the environment. Once the water goes down the drain, it will enter a network of sewers that will eventually lead to a waste water treatment station. Once the dirty water enters the treatment plant it goes through a range of treatment steps to remove such things as ammonia, solids, nutrients and surfactants – Irish Water explain the process very well here [3]

Waste Water Treatment plants can cost millions to build but also have to be maintained to a very high standard ensuring EU standard compliance is met and the water quality is brought back up to a relatively clean standard before discharging it back into the sea.

Just last week, the EPA released the Report Urban Waste Water Treatment in 2019  where the current management of waste water in Ireland is grim. It found that:

  • Treatment at 19 of the 172 large urban areas failed the mandatory EU treatment standards set to protect the environment. These 19 areas generate more than half of Ireland’s sewage.
  • Raw sewage is released into our waters every day from 35 towns and villages.

This means that the surfactants in shampoo, liquid detergent, washing powder, toilet cleaner, and other cleaning products are entering our seas and oceans untreated each and every day.

What does this mean? What are the impacts of surfactants in our oceans? According to a study on characteristics and harm of surfactants [4] its research finds that:

  • Surfactants prevent the growth of algae & microorganisms resulting in decreased primary productivity of water bodies, thereby undermining the food chain of aquatic organisms in water bodies.
  • Fish can absorb surfactants through its body surface and gills, and with the blood circulation they distribute to body tissues and organs. Contamination fish enter the body through the food chain and produce inhibition to various enzymes in the human body, thus reducing the body’s immunity.
  • Surfactants-containing wastewater discharged into the environment can cause water pollution problems. When the concentration of the surfactant reaches to 0.1 mg/L, the water may appear as persistent foams. A lot of bubbles are not easy to disappear in the water, forming foam insulating layer. The insulating layer weakens exchange between the water body and gas atmosphere, leading to reduction of dissolved oxygen which is required for a healthy water body.

All stakeholders really need to play a role in protecting our oceans from pollutants such as surfactants – we advise users to choose eco friendly products. Investment into WWTPs in Ireland needs to be made much more rapidly than it currently is.


By Ruth Clinton

Water Innovation Officer




[3] Irish Water –

[4] file:///C:/Users/User/Zotero/storage/LWHKHGRT/Yuan%20et%20al.%20-%202014%20 %20Study%20on%20characteristics%20and%20harm%20of%20surfactants.pdf

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