Researched in October, 2014
Being able to filter water, which is slightly different from purifying it, is not something that amount merely to effort. You may happen to have bleach or pool shock lying around to kill pathogens, but you likely do not have a competent filtering system.
Any commercial products mentioned on this page and specifics of some commercial brands are given as examples only. This page is no attempt at product endorsement. You can read a great deal of polemic, how claims by one manufacturer are false, endorsements by some government agency are true only to a point, etc. It's up to you to make up your own mind.
Commercial filtering systems abound. You need only Google for them using, e.g.: "water filtering."
You can build a competent and inexpensive system to save yourself a couple of hundred dollars. However, you cannot make the filters yourself. Unless you plan, in your situation, to consume the water on an on-going basis, you'll want to cover any filtering container from sunlight that would lead to algæ formation, especially in the unfiltered reservoir.
In the linked video here, the two long, black filters being used are Berkey-brand and can be purchased at this link, for about $100 for two:
Black Berkey water filtration, replacement filter source
The Berkey filters should do some 6,000 gallons of water over their life (3,000 each). Please note that even though the system filters water through two at a time, the total output should be 6,000 because each filter does one-half the water.
You can of course substitute different brands by modifying the hole sizes and topology of the system demonstrated.
YouTube page demonstrating construction of water filter.