Based upon an exchange in this question, we require complete purity in the drawing of water for the purposes of mei chatas. The setup described in Maseches Parah was essentially a ritualistic clean room to avoid impurities, and the process of gathering the water was a bit of a Rube Goldberg to make sure there was no possibility of any tumas tehom.
The discussion in Parah 3:2 suggests that we not go "too overboard" with how we go about the process, but it also suggests that direct ko'ach gavra is not a requirement in the drawing of the water. If the movements of a robot are controlled by an operator one ostensibly solves the issues of kavanah through the mechanism of grama - since the operator's intent is what is causing the action, the lack of intent on the part of the tool has no bearing on the status of the water.
Assuming there was a need to perform the drawing of water for mei chatas again, would it be possible to do so using a properly constructed robot as a "puppet" rather than the clean-room setup mentioned in the mishna? One would still need to ensure that the tool doesn't become tamei, so what other parts of the process (riding on doors on the backs of animals) might still apply?