The growing trend for artificial lawns could be raising the risk of flooding in urban areas.  

A series of tests revealed that more than 50 per cent of rainfall runs straight off some types of artificial turf whereas living lawns absorb almost every drop.

The more expensive fake grass, which is longer and tuftier, was found in the “controlled rainfall experiments” to be worse at retaining water than the cheaper and shorter variety tested.

“Significant differences in runoff were observed across all treatments, demonstrating that both types of artificial grass displayed greater volumes and proportion of runoff than living grass, and that long artificial grass had significantly greater runoff than short artificial grass,” the Kings College London study concluded.  

Most of the time water runoff in urban areas will flow safely into drains. But during wet weather most towns and cities also rely on the soil in green spaces such as parks and gardens to act as a sponge, slowing the flow of water into drains. 

Sales of artificial lawns have soared since the start of the pandemic. Dr Robert Francis, one of the co-authors of the Kings College report, is worried that if too many lawns are replaced with artificial turf British towns and cities could struggle to cope with water runoff in wet weather.  

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“The real concern is that if you have urban areas that are already susceptible to flooding… and then people start to replace green space with plastic grass, it’s possible that would be made worse because you get more runoff taking place,” he told i . 

Climate change is expected to bring increasingly intense bursts of rainfall to the UK, with tropical-style downpours set to become commonplace during the summer months. That pushes up the risk of flash flooding.  

Experts are already warning towns and cities to install more sustainable drainage systems – such as replacing patios and driveways with flower beds – to counter the mounting threat. 

Dr Francis urged homeowners considering a switch to fake grass to think carefully. 

“If you’re installing it over an impervious surface like a driveway it’s not going to make a lot of difference in terms of hydrology, but if you are replacing a lawn just think about the potential for water to come off it and where that water might go,” he warned.  

Very little scientific research has been done on the ecological impact of fake grass. The research, published in the journal Urban Forestry & Urban Greening, is the start of a series of studies into fake grass which will also look at its propensity to overheat and shed plastic particles.   

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