if my iphone 6 get water damage , what should i do , is it under warranties , if i replace a new phone how much will it cost

You should make an appointment at the genius bar of your local Apple Store and get an out of warranty replacement.

I believe the price is US$269, but I'm too lazy to google it right now.

No. It's not. The warranty is void. Accidental damage, including liquid damage, voids the warranty.

If you pay for an out of warranty replacement, the replacement phone will inherit the balance of the original warranty or 90 days, whichever is longer.