The woman suffered second and third degree burns to her legs when the toilet she was sitting on exploded from underneath her in a bar in Barcelona's Gothic Quarter.
The woman is now undergoing skin grafting on her legs. The blast was caused by the unhygienic conditions of the septic tank and the lack of ventilation in the lavatory, 'The Local' reported.
When the woman switched on the light, a spark acted as a trigger for the methane gas which filled the toilet, according to the official police report.
As the victim was sitting down, the gas was compressed therefore causing a strong blast.
The woman is suing the owners of the bar for the serious injuries she sustained.