The Water-to-Go bottle is ideal for outdoor fans

Water-to-Go water filtration system

Colour: black or white
Weight: 170g
Price: £25.00, with one filter. Replacement filters £14.95 for two
Country of manufacture: not stated

Effectiveness 38/40
Ease of use 28/30
Quality 6/10
Value for money 16/20
Total score: 88/100

Drinking water is essential for any serious trip to the great outdoors.

Hydration not only stops us getting thirsty, but helps the body perform better too.

But it’s heavy. Every litre carried adds a kilogram to the backpack, so the ability to find usable water en route is both desirable and helpful in keeping pack weight down.

But how do you know that mountain stream is safe to drink from? The last thing you want to find after filling up your water bottle is the remains of a dead sheep a few metres upstream.

There are various solutions of differing complexity and cost to obtaining clean water. Boiling kills bugs, but doesn’t get rid of metal and chemical contaminants. Chlorine tablets will sterilise water but you’re left with pretty foul-tasting liquid.

The filter is screwed into the bottle lid

Water-to-Go’s drinking bottle is a simple system.

It’s a 75cl plastic bottle with drinking spout. But sitting inside is a filter that the company claims gets rid of 99.9 per cent of contaminants.

Their list includes bacteria such as E Coli, the Weil’s disease bug, dysentery, cholera and campylobacteriosis, as well as viruses such as Norwalk, giardiasis protozoa and parasites such as cryptosporidium.

The Water-to-Go bottle’s filter will treat about 200 litres of water or last three months before needing replacement, and the company sells replacement filters online.

It warns, however, that adding cordial, energy powders and such-like will diminish the filter’s effectiveness. And it won’t treat sea water.

The filter material was, according to Water-to-Go, developed for Nasa’s space programme.

In practice, the bottle is simple to use.

Unscrew the lid and the filter, which is screwed into it separately, comes out with it. Put the lid somewhere safe and clean so as not to contaminate it, and fill the bottle from your source – stream, lake etc.

Make sure the lip of the bottle is clean and the filter is screwed in fully – there is a silicon o-ring to stop water bypassing the filter – and replace the lid, again making it is screwed on firmly to engage another, larger silicon ring.

A conventional drinking spout flips up and allows water to be drawn from it as with a conventional drinks bottle.

One advantage of the Water-to-Go over, say, a rigid alternative, is that you can squeeze the water out of the spout and transfer it to another vessel such as a hydration bladder if you prefer.

Just unscrew the lid and fill the bottle from your outdoor source

And that’s it.

We tried it and it worked – we certainly had no ill effects from drinking from various outdoor sources.

If we have a criticism, it’s the cost of replacement filters which is a bit steep at nearly £15 for two, though you can get a 10 per cent discount off them if you register with the company online.

There might be a temptation to go without replacing the filter which probably means you’re effectively just using a conventional water bottle in that case, with the accompanying risks.

More information is available on the Water-to-Go website, which also has links to purchase the bottle and filters.