A search for CP violation in the phase space of the decay \(D^+\to\pi^-\pi^+\pi^+\) is reported using \(pp\) collision data, corresponding to an integrated luminosity of 1.0 fb\(^{-1}\), collected by the LHCb experiment at a centre-of-mass energy of 7 TeV. The Dalitz plot distributions for \(3.1\times 10^6\) \(D^+\) and \(D^-\) candidates are compared with binned and unbinned model-independent techniques. No evidence for CP violation is found.