Titanium　dioxide　nanoparticles　(TiO2　NPs)　are　an　emerging　environmental　concern,　considering　their　proven　toxicity　and　wide　commercial　application　nowadays.　Once　entering　natural　water　bodies,　they　might　become　a　challenge　to　conventional　water　treatment　techniques.　In　this　pioneering　study,　coagulation　was　found　to　achieve　86%　of　concentration　removal　and　74%　of　turbidity　removal　of　TiO2　NPs　in　natural　lake　water,　when　the　initial　concentration　was　1　mg　L-1　and　the　corresponding　turbidity　was　2.3　NTU.　Furthermore,　the　zeta　potential　seemed　not　to　be　the　only　decisive　factor　in　the　coagulation　effect.　Further　studies　on　the　clarification　of　the　mechanisms　involved　are　hence　recommended.　©　2017　The　Chemical　Society　of　Japan.