No, 1000L/day is about right for a typical American household. [1] claims "The average American family uses more than 300 gallons of water per day at home." 300 gal is 1136 L.

https://www.epa.gov/watersense/how-we-use-water

I know American toilets are comically big but 250L a day on flushing them seems insane to me. A cursory google suggests the average UK household uses 350L a day in total!

That's like 20 flushes. It's a lot more than I'd expect for "typical". Maybe a family of 5 does 20 flushes. Or maybe it's 2 people with strict anti-if-it's-yellow policy.