I find it rather hard to drink water after Kava this is why you should hydrate before.
Drink a litre 20 minutes before works well.
My water filter holds 8 Litres and I go through it every day. This is a mixture of Kavas, Teas, and water. Half for just water.
Point is to just drink water throughout the day, and forget trying after Kava.
How I do it.
Also eating watermelon after Kava.