I’ve heard that cordials can be used for water sterilisation from quite a few reliable sources. A quick search reveals that at least some kool-aid type drinks can be used for water purification.
It has also been reported that ordinary cordial will offer some protection.
I have extensive backcountry experience, and have often relied on questionable sources when travelling through the wilderness. Over the years I’ve learned a few things about dealing with the problems of obtaining safe, potable water. For this post, I will refer to the Backpacker’s Field Manual, the US Army Survival Manual, and my own experience.
First, the kinds of contamination:
Biological - any microorganisms in the water have the potential to cause serious illness or death. Giardia is quite common, particularly where large animals congregate and in beaver ponds. In the US, I understand that it is a more common ailment out west where you’re likely to travel through land that has some role in ranching.
Toxic - any pesticides, debris from mining operations, heavy metals. Nothing you can do in the field will remove these contaminents - not chemical treatment, not boiling, not even distillation. Fortunately, in most cases, this kind of contamination is obvious. Although, if it isn’t good luck!
Types of treatment:
Filtration - Simply removes particles larger than the membrane size of the filter being used.
Purification - A treatment which kills microorganisms
Methods of treating suspect water:
Boiling - expensive in time and fuel, but it is the surest way to destroy all microorganisms. This is purification of last resort, when your only source is a muddy, swampy, stinky hole.
Chemical Treatment - any chemical treatment varies in effectiveness depending on temperature, pH and water clarity. If the water has lots of particles in it, they should be filtered, because only the outside of the particles will be cleaned. You should wait 30 minutes after treating the water before drinking it. If you use tablets, don’t start counting until the tablet is fully dissolved. Aerating the water afterwards will improve its flavor, as will adding salt, drink mixes like Kool-Aid, or hard candies. Iodine is light sensitive and has a relatively shotr shelf life. It’s more effective than chlorine for treating Giardia, but will not kill the insidious Cryptosporidium. people can react poorly to iodine and some are even allergic. Iodine is available in liquid or tablet form. Chlorine is also available in both forms. It is a common alternative and works similarly.
Filtration- There are an extraordinary variety of filters on the market. In test, sports bottle filters have proven to be almost universally ineffective. Most filter manufacturers exaggerate the capabilities of their filters, so read the documentation closely. You should tailor your filter to the types of organisms you expect to encounter, paying careful attention to the pore size of your filter’s membrane. Virii are as large as 0.004 microns and can pass through most filters easily. To be effective, this kind a filter should also have a purification element. Filters have become less expensive recently, but they require frequent maintenance to prevent clogging and rough handling can easily damage filters that rely on depth filters (porous materials like carbon that trap particles). Remeber, purification is the only sure way to prevent infection. Check the flow rate, too - it can take a long time to pump a 1 liter bottle. Also be aware that the business end of your filter needs to be isolated from all other elements to prevent cross-contamination.
How to pick a good water source:
Your particular case:
With only a large bottle, you have two otions: boiling, or natural filtration. Pick the best water source you can find. You will need some other container to hold the filtered water. Improvise. Fill your bottle with alternating layers of sand, crushed rocks and charcoal from your fire. Fill the bottle with water slowly. Then, suspend the bottle upside down and funnel the water into your new container. Another method of filtration is to dig a hole in the sandy banks of a stream, the sand will act as a natural filter. However, if your bottle can withstand the temperatures, boiling is the only way to go.
Reality Check:
If you are in a survival situation, microorganisms in the water are the least of your worries. it takes from several days to 2 weeks for the common infections to take hold. Drink from the best source you can find and get yourself out of trouble. A few weeks of painful diarrhea are a small price to pay for saving your own life.
My Particulars:
I carry bottles of iodine tablets and sugarless drink mixes on treks of up to three weeks. I’ve never liked filters because of their inefficiency, cost, and pack weight. A bottle of iodine tablets and neutralizers costs about US$5. If I ever develop the urge to trek through Third World countries, I’ll surely carry a combination filtration/purification system, and probably still boil. 
Historical Anecdote:
In the 1970’s human waste was airlifted by helicopter out of remote backcountry facilities in large drums. At Kinsman Pond in the Franconia Range, a pilot accidently tipped his load and it toppled into the water. Needless to say, no one drank that water for years. Even today, it’s icky - though mostly due to sediment of a different nature.
One other aside. You may enjoy reading How to Stay Alive in the Woods by Bradford Angier. It’s a classic.
If you are near rivers and streams wouldn’t it be safer to set up a catch system to collect dew. The op didn’t specify weather he was constantly on the move.As a matter of fact drinking water from one source indicates he isn’t moving.
This is an extremely inefficient method, suitable primarily for desert survival where free-flowing water is non-existant or when a crippling injury that restricts mobility. Dew collection systems usually use tarps or sheets of plastic. One large container couldn’t collect enough to sustain life. Why die of thirst drinking dew when water is plentiful throughout most of North America? There’s no need to be THAT cautious.