This paper provides the gist of the systematic review undertaken, involving evaluation, analysis, repackaging and modelling of all the literature that could be sourced on the subject. Copper slag (CS) and washed copper slag (WCS), as to be expected, have essentially similar basic physical (although WCS is usually finer than CS) and chemical characteristics and therefore they can be treated as one material. In-depth analysis of 2192 test data sourced from the literature showed that, given all the basic material characteristics, CS/WCS can be used as the sand component for making all strength grades of concrete and giving similar (or in some aspects better) performance to the corresponding concrete made with natural sand. The special attribute of CS/WCS for lowering the mix water demand has been used by the authors to develop two simple models for utilising the potential water savings and estimating the strength gains that can be realised when designing concrete with CS/WCS for given strength at a specific age. It is demonstrated that the water-saving potential of CS/WCS can be used to make other recycled and secondary materials more acceptable for use in concrete.