I drank so much water today and only went to bathroom a few times...?

[loudmouther187]

About a week ago I drank for three days straight... Now for the past few days I have been drinking lots of water. I just started to urinate normalily throughout the day. But at night when I sleep I need to get up every 10 to 15 minutes to use the bathroom. Plus my legs below the knee have been swelling.. I know this is my body retaining water because when I lay down I get up to urinate for about 2 hours straight. Why is this?