Hi Michael, I was about to ...

Hi Michael, I was about to reference my experience in NWL, but I guess you would know that more than I these days!

Globally my expereince backs up your comment re "no right answer". I think it depends on the appetite for risk, ie likelyhood and consequence. Age of network assets, key customers in network, confidence in response to rectify, water quality, and ability to rezone.

I would suggest putting all these things into the mix for the specific situation, get the Ops guys involved and work through it. Personally I would think that (given the focus on customer experience) 24 hours is excessive unless its impossible to rezone. My starting point "rule of thumb" has always been 18 hours (taking into account likely growth), noting that the risk analysis may push that up, or even knock it down a tad.