Without a doubt get the water turned on before closing. Asking for a seller hold-back will only cover so much. Depending on how and if it was winterized there could be massive damage that might make you reconsider buying the house at all; even if the sellers were to fix it. Water damage can be a nasty thing.

I would definitely recommend a complete home inspection before purchasing! If a satisfactory home inspection was a contingecy on your contract and it wasn't satisfied, you have the right to extend, cancel, or modify your offer to purchase. Good luck to you.

I would figure out a way to get the water on before closing if I paid for it myself. I had one here in central Georgia that sat (a foreclosure) for a year before it was on the market. Even with our temperate climate there was a lot of damage from frozen pipes. Luckily the asset company paid for the $4000+ worth of damage. I would not consider a home inspection complete unless all utilities were functional. In Georgia for FHA or USDA the appraiser has to note that the water (among other things) is functional.