It is getting a little late even for me so I will have to make this quick.
If by 2 liter bottles you are referring to plastic bottles that once held Soda like Coke Pepsi etc then the water will not last very long. I have read that bottles that have held anything except water should not be used since plastic absorbs a little of what was in it and it will contaminate the Water after a while, which is not a good thing for long term storage.
What I used to do when I thought I might need to have water stored was to use bottles that once held Spring Water and I also used one Gallon bottles that once head Cranberry Juice and when the emergency was over I got rid of the water in the juice bottles.
Now as to Water Filters etc.
First thing that needs to be considered is where are you getting the water from and what might be in the water.
Next thing is are you looking for something to use for your home water use or for in the field.
Now as far as I know boiling will kill all biological contaminates but is a big pain and requires the use and consumption of fuel which may be in short supply and it take a little while.
Filters work fine as long as you use them correctly except most of them don't filter out Viruses since a virus is too small to filter. The only Filters that will remove Viruses are Reverse Osmosis Filters. Reverse Osmosis Filters are also the only way other then Distillation which will filter out Viruses and they will also convert Salt Water to Drinking Water, which if you live near the Ocean may be very useful.
Also some Filters contain Activated Carbon to get rid of Chemical Contaminants
As far as I know the only other ways other then Reverse Osmosis to get rid of viruses is through the use of chemicals or boiling.
Now as to your PUR Filter it may or may not remove or deactivate Viruses. Some PUR filters use a chemical to kill viruses and a regular filter for everything else.
Now as to the danger of Viruses, I have read that Viruses are not that much of a problem unless you are in an area where there is a chance of contamination cause by people, if you are in a remote area basic filtration is all that is required.
What I use is a Katadyn pump type Filter, and the reason I bought it was because it can be used to Filter 11,000 Gallons of water before requiring a new filter.
The PUR Filter used for camping does not Filter as much water and the big problem is it can only kill viruses from a very small amount of water. So while is is very good for camping or a hunting trip it is not good for long term survival.
My suggestion for a low cost home Filter is a Katadyn Drip Filter that should supply enough water for your family depending of course on how large your family is. My mother had 13 brothers and sisters.
There is another drip filter the BRITISH BERKEFELD, it is supposed to be good but I don't know much about them. The only thing if anyone does get a BRITISH BERKEFELD please don't get it from John Manity from Frugals, since I think he is a total jerk.
And for short term use in the field the PUR is probably as good as any other, for long term use the Katadyn.
Now if it can be afforded a good Reverse Osmosis Filter would be best for your home and Reverse Osmosis Filters are also available for use in the field.
The biggest problem with Reverse Osmosis Filters is their Cost and Size but if you want the safest water then they are worth the cost if you can afford one.
There are also Water Distillation systems for your home that are not too costly but they need electricity to function.
Also you can make your own still that does not require electricity, Moonshiners have been doing it for a very long time, the only difference is you will be using it to make drinking water, the principle is the same.
This is the filter I currently have except I have the older model without the output hose:
http://www.waterfilters.net/Katadyn-Pocket-Camping-Water-Filter_p_0-334.html These are the other Katdyn filters:
http://www.waterfilters.net/Filters/campingfilters/campingfilters.htm BRITISH BERKEFELD Filters:
http://www.arctic-1.com/filters.htm Reverse Osmosis Filters
http://www.freedrinkingwater.com/water-contamination/water-contaminants-pollutants-list.htm http://www.home-water-purifiers-and-filters.com/reverse-osmosis-filter.php Counter Top Filter
http://www.ecrater.com/product.php?pid=6375020 For Camping:
PUR
Survivor 06
Manual Watermaker
Weight about 2 ½ Lbs
http://www.landfallnavigation.com/-sas07.html PUR
Survivor with higher output of 1.2 gallons/hour
http://www.landfallnavigation.com/-sas35.html Other models
http://www.landfallnavigation.com/watermaker.html For camping??
http://www.alibaba.com/product-free/101278959/Camping_Reverse_Osmosis_Unit.html I hope this has been of some help.
I seem to have made a longer post then I originally intended, oh well.
