MP1 tabs are great. I use a coffee filter to pre-filter the water (basically to strain out all the larger dirt and what-not), then add the appropriate amount of MP1 tablets. Gives water a slight chlorine taste, but it's no worse than a lot of tap water I've drank over they years, and it sure beats getting sick. One thing I really like about them is that they kill cryptosporidium, giardia, viruses, and bacteria; most of your other common methods do not work against all of them.

(For example, most filters fail to filter out viruses; Iodine and regular chlorine fail against Cryptosporidium.)