The Commission intends to set standards that toilets must meet to earn the European Union’s eco-label, which certifies that they are environmentally friendly.
To meet the criteria, toilets must flush no more than six litres of water and toilets with a ‘low-power flush’ option should use no more than three litres.
According to the Commission, the UK flushes the most, having used 1,125 million cubic metres of water in domestic toilets in 2010.
In the UK, some toilets have cisterns with a capacity of 7 to 9 litres.
The Commission said: “Two key elements appear to affect the water consumption of flushing toilets and urinals: their design and the user behaviour.
“User behaviour is a crucial aspect and must be without any doubts emphasised.”
However, Paul Nuttall, UKIP deputy leader and MEP, said that the research carried out by the Commission was a waste of taxpayer’s money.
“It is particularly ridiculous considering that Commission President José Manuel Barroso, recently said the EU executive should be ‘big on big things and smaller on smaller things’.
“The world is in a financially parlous state and thanks to nonsense EU carbon targets, energy bills are forcing families into fuel poverty. And yet money is being thrown away on efforts to deliver an eco-label for toilets and urinals,” he said.