2010 Nitro Z-7; plug securely in live well drain. however, water fills live well - why??[/i][/u][i][u]

Maybe through the fill port.

May be come in the overflow drain when you come off plane. Open the live well cover and watch it to see.

It's not uncommon to have water come through the suction side of the pump and get through the pump body and trickle into the livewell.

With where the suction is on the underside of the stepped Transom, you get a little head pressure, just enough to work it's way into the livewell. When you come off the trailer and hit reverse pretty good it really gets in even more so.

check to see if you have a check valve on the drain side, had to put one in my champion to keep it from filling.

only lets water flow out, not back in thru the drain.