UK health bodies say not to drink untreated water, and they name streams among the places the parasite cryptosporidium turns up. If your water may run out on a long hill day, carry a filter.
For most walkers that means the LifeStraw Peak Series Collapsible Squeeze Bottle 1L.
You fill it at the stream and drink through the filter.
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The three, by how you drink:
- To fill a soft bottle and drink from it, choose the LifeStraw Peak Series Collapsible Squeeze Bottle 1L.
- To fill a pouch and squeeze it into the bottle you already carry, choose the Sawyer Squeeze.
- To carry the lightest filter, a straw that also screws onto a bottle, choose the LifeStraw Peak Series Solo.
| Your day out | What to carry |
|---|---|
| You want one soft bottle to fill and drink from | LifeStraw Peak Series Collapsible Squeeze Bottle 1L |
| You want to fill a pouch and refill the bottle you already carry | Sawyer Squeeze |
| You want the lightest filter, as a straw or on a bottle | LifeStraw Peak Series Solo |
LifeStraw Peak Series Collapsible Squeeze Bottle 1L
You want one soft bottle to fill and drink from
LifeStraw Peak Series Collapsible Squeeze Bottle 1L Soft 1 L bottle with its own filterDrink from it, squeeze it or sip through it Read the full specification on AmazonA soft 1 litre bottle with its own filter. You fill it at the stream, then drink from it, squeeze water through it into a pan or a mug, or sip through it like a straw.
The filter lasts up to 2,000 litres, and when it is spent the water stops flowing.
That figure is LifeStraw’s. A backwash syringe comes with it, so you can flush the filter clean.
Best for: a walker who wants one soft bottle to fill and drink from.
Sawyer Squeeze
You want to fill a pouch and refill the bottle you already carry
Sawyer Squeeze Water Filtration System Filter screws onto a pouch or a 28 mm bottleFilter alone about 85 g Read the full specification on AmazonA small filter that screws onto a soft pouch. You fill the pouch at the stream, then drink straight from the filter or squeeze clean water into your own bottle.
It also screws onto a standard bottle with a 28 mm thread.
The filter alone weighs about 85 g, and Sawyer backs it with a lifetime limited warranty.
Sawyer says it needs backwashing more often in muddy water than in clear water.
Best for: a walker who wants to fill a pouch and pour the water into a bottle they already carry.
LifeStraw Peak Series Solo
You want the lightest filter, as a straw or on a bottle
LifeStraw Peak Series Solo Personal Water Filter Straw filter, 48 gScrews onto most 28 mm bottles Read the full specification on AmazonA straw filter of 48 g. You drink through it straight from a stream, or screw it onto most standard 28 mm bottles.
No bottle comes with it.
It filters up to 2,000 litres, then the water stops flowing, by LifeStraw’s figures.
A backwash syringe comes with it for cleaning.
Best for: a walker who already carries a bottle and wants the smallest filter to fit it.
What these filters stop, and what they do not
All three are sold as removing bacteria and the parasites giardia and cryptosporidium.
None of the three claims to remove viruses. LifeStraw says that neither of its two filters does. Sawyer’s product page and FAQ say nothing either way.
Why stream water needs treating
UK health bodies are plain about it: do not drink untreated water.
The UK Health Security Agency says cryptosporidium can be found in the faeces of infected people and animals, and that farm animals are particularly affected.
It says the parasite may contaminate streams and rivers, and that manure can carry it into fields and rivers.
Public Health Wales gives the same warning about streams. The NHS says you can catch giardiasis from drinking water contaminated by the poo of infected people or animals.
Where to fill
Mountaineering Scotland gives this advice for the Scottish hills:
- Take water from a flowing stream, not still water.
- Collect it upstream of houses and camping spots.
- Avoid muddy water, and water where there are a lot of livestock.
- Avoid water that looks stagnant, discoloured or oily.
Fill from running water above the farms, then filter it anyway.
In frost
Sawyer says to keep its filter in a pocket or close to your body in freezing weather. It says to replace a filter you think has frozen.
Tablets and boiling
Tablets weigh almost nothing, and a BMC panel contributor suggests carrying them for streams on the Welsh 3000s.
In its advice for travellers, TravelHealthPro says chlorine tablets do not always destroy giardia and cryptosporidium. It says cold water can weaken chemical treatments, and that chlorine dioxide works better against parasites.
Boiling works too. Mountaineering Scotland says to hold a rolling boil for one minute, which does not remove sediment.
Water on Yr Wyddfa
There is no tap at the summit of Yr Wyddfa, and the Eryri National Park Authority says to carry at least 1.5 litres each.
The Authority asks walkers to fill the bottle to the brim before setting off. Its designated water taps give water that is safe to drink.
The rest of your kit is on the what to pack list, and your day rucksack decides how you carry the water.
We compile and explain public route and safety information. We guide nobody and sell nothing on the hill.
Start full, fill from running water if you run short, and filter every refill.
