It's far from ideal, but retrofitting can be very problematic depending on construction type, route options and internal wall/floor finishes. Irish water will not go to additional risk or expense to route pipes internally in most cases. Their responsibility legally ends at the boundary of your property, so if you want a solution other than the effective good will offered under the first fix free program, you will likely have to pay for it yourself.
Try around a few local plumbers and see what they'll charge you to route it internally and what disruption the work might cause?