Vomiting

[Bramblebeep]

DD is 4. She's been vomiting for about 8 hours.
After each episode she's so thirsty but then 20mins later she sicks it all back up.

I'm trying to give her diarolyte but she hates the taste.

She's sleeping in between and talking normally when awake. She does seem too dehydrated although hadn't weed for about 9hours.

How long do I let her go on like this?

I'd ring 111, that's a while without wee

Hope your DD's over the worst by now OP.
From what you've said it sounds like a pretty typical sickness bug. If you're giving her a drink straight after being sick that's probably prolonging the vomiting. Wait an hour after vomiting before offering a drink if possible, then only allow a small sip every 20 mins or so. Once she had gone a few hours without being sick you can start to offer a little more to drink and maybe some small plain food when she wants it.
A 4 year old won't be dangerously dehydrated from 8 hours of on/off vomiting, but if she still hasn't had a wee by now 111 might be a good idea.