On International Water Day, Christian Payne reviews the smart, compact and simple Sawyer water filter that will mean an end to the waste and expense of bottled water when travelling

I nearly died once in India after drinking contaminated water. A messy, unpleasant experience I have no intention of ever repeating, especially if all I have to do is invest in a filter or purifier.

As I write this I'm sat in a hotel room in Bogatá, Colombia. There are five different brands of bottled water in the room. And one tap. I'm told the water in the tap might be OK to drink. But there's no need for me to take any chances as it only takes a minute to filter my own.

Quite simply - carry a refillable bottle instead, and top it up from the tap.

Depending where you are of course, that can be a more or less risky proposition, because you can't always be sure the water is clean enough to drink.

If you are uncertain of how clean your water source is, buy a water filter. There are many on the market, including ultraviolet light pen purifiers, pump-action, gravity fed, and squeeze filters. Some are monsters designed for the great outdoors that you wouldn't or couldn't reasonably ask anyone to carry one around with them at all times, but that's not the case with the eminently portable small Sawyer filter.

I first heard about Sawyer from a friend who has taken various water filters around the Middle East on his work travels, and who always ends up breaking them from repeated use or finding irritating niggles; the Sawyer filter was the first one he had no complaints at all about.

As with any filter, you've got to read the instructions before you use it. It's extremely easy to use - I'd say idiot proof, really - but nonetheless must be used properly if you want it to filter out the bacteria that otherwise will make you sick.

Also remember with this particular filter that is it not a purifier. That means it does remove bacteria - E coli, salmonella and those causing cholera and typhoid - but it does not remove viruses, which are physically smaller and can therefore slip through its 0.1 Micron rated filter membrane.

To remove viruses with a filter you need something as small as 0.01 Micron, or you end up having to use a UV pen, chemical tablets or boiling to make sure the viruses are gone. That, of course, adds hassle but is worth it if you're in a place where the water might be contaminated by animals or humans.

Sawyer does make what seems to be a pretty revolutionary filter that takes viruses out too - most filters cannot - which means no need for chemicals, boiling or UV light. It has a 0.02 micron membrane.

But, a filter - not purifier - is something I'm more than happy to use for domestic back country travel or suspect tap water. The beauty of the Sawyer Mini is that, while it is suited for the rigours of use by Bushcrafters and survivalists, it is also small, light, portable and easy to use for anyone who needs clean drinking water from mildly questionable water sources. You really can carry this filter around all day in your pocket.

The Sawyer Mini Filter sell for between $20-$35 in the US and around £29 in the UK.

This filter pays for itself after you've filtered 14 litres of clean drinking water you'd normally pay for. And this one just keeps on going; if you used it for your recommended daily intake of three litres of water it will last you 347 years.

Most filters don't have that kind of longevity, and often have expensive ceramic elements that need replacing pretty regularly because they wear out.

Fragile ceramic filters need to be carefully taken apart and cleaned by hand. The Sawyer mini comes with a large "cleaning plunger" syringe used to "backflush" the filter, dislodging and flushing any particulates that may clog the filter and shorten its life. It's a four-minute job, if you're slow.

The kit also comes with a straw attachment for drinking straight through the filter and there's no need to pump, as you do with some water filters.

The only negative is that as with most filters, it will break if water freezes inside it because the frozen water expands and breaks the filter elements. It means keeping the filter in a pocket close to your body if you're somewhere that cold.

There are many reasons not to buy water in plastic bottles. It's expesive both financially and ecologically, and extremely wasteful of resources.

We consume 50bn bottles of water every year (30bn of those in the US), but it takes roughly three times the volume of water to manufacture one bottle of water than it does to fill it, and there's a huge amount of oil used in its production and transportation too.

Although made with recyclable plastics, plastic bottles don't biodegrade – they photo-degrade, breaking down into smaller fragments over a very long time that contaminate soil and pollute waterways. Then there's the impact on the animals that digest those plastics, some of which we then go on to eat.

According to the Ocean Conservatory, every square mile of the ocean has over 46,000 pieces of floating plastic in it. Plastic bottles and bags are also the most common form of pollution found on our beaches and in our oceans.

Anyway you look at it, bottled water is an expensive way to waste money that I'd certainly rather spend on almost anything else.