PO440 ??? Could this happen???

[prolandco]

I put a 10k motor in my truck and bought a code reader cleared the SES light and for the 1st time no SES light. Then I took the family to the lake with the boat and had to back out pretty deep to unload and load the boat. On the way home the SES light comes on and there is a grumbling sound coming from my dash behind the steering wheel, I get home and put the code reader on and PO440 and PO440pd (EVAP malfunction). On another thread I read about PO440 and they said the charcoal canister and a test control are located in the rear of the truck, has water affected the canister or something else to cause the grumbling and PO440? PLEASE HELP IF POSSIBLE!!!!!!!