What type of snake is this?

i found a snake coming out of a creak.it was white with brownish red patches with black borders.i picked it up and it kept biting me. i took it home and put it in a huge fish tank with fish,logs,mulch beding,water,rocks,caves,and a heating lap it loves it but its not white any more its brown with brown patches and a black border the under side is black with whitish gry dots and a tan line running down it its chin is white.me and my mom think its a northern water snake but where not too shore and if you need to see pic of it just send me a email at pkurnava@yahoo.com