It depends on where you live and how well supported your race will be.

I personally almost never carry water with me unless all of the following are true: it’s really hot, I’m running somewhere without access to water fountains and I’m running more than about 10mi (16k). I have a backpack for those times and a handheld for shorter runs in extreme heat.

All this to say it’s a personal choice. If you’re ok running with more stuff on you and/or you want to avoid having to look for water fountains if it’s hot, give it a try.

I’ve never brought water with me on a race and the ones I’ve done have all been well supported with regular aid stations. I’d recommend alternating between water and the available electrolyte drink between aid stations.

It can’t hurt to use a few gels during your race. Of course, you should try them out before your race. There will be some disagreement on whether or not calories/carbs are needed for a half, but I’ve found them to be helpful. One 5 min before starting and then one every 40-45 min.