The design of water and ore addition points has an important bearing on the ease of operation of a grinding circuit. The nature of some of the design decisions and the possible options of the designer are discussed. For example, design decisions determine the ease of alteration and measurement of flowrate, the ease of maintenance, and the effectiveness of feed- back control loops which maintain material inputs (water and ore) at required values. To illustrate discussion in the paper, a grinding circuit which contains one rod mill and one ball mill in series is used. Practical ramifications of desigl decisions :;ne stressed.