It is difficult to provide a useful answer to this question without additional information. For example, what is the system pressurization - operating psi/bars? Having installed ductile iron water mains, and having pressure tested new installations to destruction (resulting from hairline cracks in new pipes), I can confirm that the effects can potentially be devastating to infrastructure - especially roads and possibly other foundations/buried structures. In addition to the obvious negatives associated with traffic disruption and reinstatement, there will also be substantial water losses should this happen.
Where HDPE pipe is used, one of the predictors of service life is the cyclic nature of the pressurization. Cyclic pressurization may not lead to catastrophic failure, as it could for ductile iron, but it will certainly shorten the lifespan of the network.
What is the nature of the network design in terms of control points? Can the network even be controlled? The valves, tees and joint connections will likely be the most fragile part of the system.
Nonetheless, in my view the best chance of implementing such a programme successfully would be to partially shut down the network on a rotational schedule in such a way that essentially the entire network would have a chance to stay pressurized - or at least ensure that the portion of the network that is exposed to risk would be minimized. This would require endpoint valves however. It could be possible, depending upon the nature of the network, to install these at strategic locations.
Whether such an approach is economic, or would provide any benefits at all in terms of a reduction of water consumption, is another question. My guess is it may not, but then again a rationing programme may not be enforceable either.