Gear Review: Water Filters

Staying hydrated is crucial for both enjoyable day walks and multi-day hikes. Getting hold of additional water on a walk in Scotland is often not a problem, but knowing whether it is safe to drink can be. The presence of animals (who will be defecating and sometimes dying near or in water sources) and humans who may be contributing chemicals as well as their own waste to the environment can result in nasty illness as a result of drinking contaminated water.

People can also be worried about industrial, agricultural and sewage effulent as well as micro-plastics in water. Unless you can be 100% sure about your water source, its best to try and ensure drinking water is free of bacteria (E.coli, Salmonella, Cholera etc), disease-causing protozoa such as Cryptosporidium and Giardia (more of an issue overseas), chemicals, sediment and particles either using chemical treatment or filtering. We’ve been looking at a number of lightweight water filters as an alternative to our usual chemical treatment when we want more water than we are carrying.

The models tested are all designed for lightweight backpacking and day walks and work by squeezing water through a series of filters that remove bacteria and protozoa. All require some maintenance and you need to be scrupulously careful to keep clean and contaminated water (and containers etc) separate during the procedure, and to properly clean and dry the filters once back home. All the designs tested can be compromised if dropped, frozen or subject to extreme heat (60°C – so don’t dry on a hot radiator at home). However in general, and after a bit of practice (its best to run through the instructions a couple of times before you head out), we found them fairly easy to use and great for backpacking and bothy trips. I’m also going to be taking one on hot days rather than lugging my usual 2+ litres of tap water. During testing we looked at weight (all components supplied with system included in weight given), size, speed and ease of use, maintenance, what they claim to filter out, and price – here’s what we found:

Platypus Quickdraw Microfilter System

Recommended price: £49.95
Weight: 95g

This is a straightforward filter that comes with a 1 litre bladder. Fill the bladder (we liked the wide hole and small carry handle which made it easy to fill from streams) and then unscrew the cap on the end of the filter marked “dirty” and un flip the lid at the “clean” end. Point the clean end of the filter into another bottle (or drink direct) and just squeeze or roll the full bladder until all the water runs through the filter. This was relatively easy to do single-handed and in cold conditions. The filter is made from a grippy material that is easy to handle and I found it performed quickly (Platypus says its flow rate is equivalent to 3 litres a minute). The bladder is the same robust material as other Platypus bladders and I’d expect it to last well. It rolls up small and as well as fitting with other Platypus products it also works using a standard water bottles with 28mm opening. I liked the easy flip lid and small spout at the clean end which makes it easy to squeeze the water into any container or drink directly if need be.

Platypus say this filter should last for 1000 litres (which is less than the other brands tested) before the filter part needs to be replaced. It’s recommended you clean the filter every 8 litres to stop it getting clogged. This is really easy to do as you just need to vigorously shake the filter part way through the filtering process. If the filter remains slow or clogged there is also the option to backflush which is basically operating the filter the other way round using clean water – no separate backwash syringe is needed.

Platypus says the QuickDraw removes 99.9999% of bacteria and 99.9% of protozoa using filter pore size of 0.2 micron.

Pros – lightweight, easy to use and clean, attached flip lid keeps the spout clean and less likely to be lost

Cons – filter cartridge needs to be replaced after 1000 litres

LifeStraw Peak Collapsible Squeeze 1lt

Recommended price: £49.95
Weight: 110g

This is a grippy 1 litre bottle with an internal removable filter attached to the lid. To use simply remove the filter and lid, fill the bottle (nice wide opening but no handle so your hand will be in the water) and then replace the filter and either drink directly from the integral spout or squeeze the bag to pour the clean water into another container. If drinking directly it takes a bit of effort to get the water to flow but after the first few sips it works well and is the best design for direct drinking than the other models. The flow rate seemed slower than some of the others although LifeStraw says it can filter up to 3 litres per minute. The water bottle material is lovely to handle even with cold, wet, hands and seems robust. The cap is fairly easy to turn with cold hands. The filter on its own can be used as a straw and is also designed to be used with other LifeStraw Peak Gravity systems (hydration bladders etc).

LifeStraw says the filter should last for 2000 litres before it needs to be replaced. It recommends backwashing regularly rather than stating after a certain number of litres. To backwash a separate plastic syringe (included in the total weight) is used to draw water back through the filter. This is slightly fiddly, especially with cold hands, and means you have to remember to pack the syringe. For long term storage of over a month LifeStraw recommends making a saline solution of salt and water, this also involves using the syringe, and then the filter has to be backwashed again with clean water before use.

LifeStraw says it removes 99.999999% of bacteria and 99.999% of protozoa and 99.999% of micropastics using a filter pore size of 0.3 micron.

Pros – Good for drinking directly from bottle, grippy and robust design.

Cons – Slower if large amounts of water needed, syringe needed (included) for backwashing.

Alpkit Hippo

Recommended price: £24.99
Weight: 55g

This is a basic, gravity feed or direct drinking, system consisting of a lightweight filter with clean and dirty ends clearly marked, a plastic tube and a 1 litre pouch with sport bottle lid. To use the gravity method fill a normal bottle or hydration bladder with 28mm hole with water and attach to the dirty end of the filter. Attach to another bottle/bladder and hold up the whole system or, if using a pouch or bladder rather than a rigid bottle for dirty water, squeeze to filter the water through. Alternatively the straw can be connected to the dirty end and placed in the water source to allow drinking directly from the filter’s clean end. This works well and the straw means you don’t have to crouch quite so close to the water as the some models. The gravity feed is not quite as smooth as the other systems but does work well, if a little slower, after practicing the set up. It’s good for doing larger amounts of water if not in a hurry. The supplied water pouch feels a little flimsy, but most people will prefer to use this system with their own bottle or bladder anyway.

Alpkit says the filter should last for 3000 litres. It has a transparent window so you can inspect the filter, and the maximum flow rate is 1 litre per minute. Alpkit recommend backflushing the filter every 10 litres – this is easy to do, no syringe needed. It also recommended that the filter is sterilised using a mild bleach solution and dried at room temperature before long term storage.

Alpkit says it removes 99.99% of bacteria and 99.99% of protozoa using a filter pore size of 0.1 micron.

Pros – Lightweight, good value.

Cons – Slower filtering rate, supplied water pouch flimsy.

MSR Trailshot Microfilter

Recommended price: £74.95 (widely for sale for less)
Weight: 142g

This pocket-sized filter works on the same principles as the other filters but is particularly good for drinking directly from water sources. It is very small so will particularly appeal to runners and day walkers who want to stuff it in a pocket. Simply put the dirty end of the hose into the water source and squeeze the flexible bulb surrounding the filter repeatedly to get the water to flow. Drink directly from the intergral spout with flip lid or keep squeezing to fill bottles etc. It does not fit with other elements of MSR’s Trail Base filter kit and so can’t be hooked up to these to create a gravity feed system. The design and materials feel robust and are easy to use with cold and wet hands. The end of the tube does need to be held or wedged under the water. The amount of squeezing needed gets tiresome for large volumes and about 3 or 4 initial squeezes are needed before water starts to flow.

MSR says the filter should last for 2000 litres and has a maximum flow rate of 1 litre per minute. It is recommend the filter is cleaned every 8 litres – this is very easy, simply half fill the bulb and shake vigorously for 20 seconds. MRS recommended that the filter is sterlised and dried at room temperature for a week before long term storage.

MSR says it removes 99.9999% of bacteria and 99.9% of protozoa using a filter pore size of 0.2 micron.

Pros – Small and packable, long straw good for direct drinking, robust design and materials.

Cons – squeezing method tiring and slow for large quantities.

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