Portable Water Filters: GRAYL vs Katadyn BeFree

One is None, Two is One

Water filters are NOT all the same. And understanding the difference could save your life.

I carry BOTH a GRAYL GeoPress AND a Katadyn BeFree — but in different places and for different reasons.

One is none, two is one. Every one of my bags has TWO filters in it.

Filter vs Purifier — The Critical Difference

A filter physically strains out contaminants based on pore size. Think of it like a screen door — stuff bigger than the holes can't get through.

A purifier goes further. It removes particles AND eliminates microorganisms, pathogens, and chemical contaminants that filtration alone can't address. Purification is what you need when water safety is uncertain or when there's any risk of biological contamination.

The key difference? Viruses.

The Science: Size Matters (Microns)

Here's why this matters — it's about size:

• Protozoa (Giardia, Crypto): 5-15 microns → ✅ Caught by 0.1μ filter
• Bacteria (E. coli, Salmonella): 0.2-5 microns → ✅ Caught by 0.1μ filter
• Viruses (Norovirus, Hepatitis A): 0.02-0.3 microns → ❌ TOO SMALL for filters

See the problem? Viruses are TINY — 0.02 to 0.3 microns. A standard 0.1 micron filter physically cannot block them. They slip right through the pores.

Most filters handle bacteria and protozoa just fine. But viruses require either chemical treatment, UV light, or a purifier that uses something other than pore size.

How Purifiers Work (When Pore Size Isn't Enough)

The GRAYL GeoPress uses electroadsorption technology. Instead of relying only on pore size, the cartridge contains positively charged ions that act like tiny magnets — actively attracting and capturing viruses, bacteria, and other contaminants that would slip through a standard filter.

The cartridge also includes ultra-powdered activated carbon to adsorb chemicals, pesticides, and heavy metals.

This is why GRAYL meets the EPA's water PURIFIER standard (independently tested, NSF/ANSI protocols 42 and 53) — not just a filter standard.

When Do You Need Virus Protection?

Use a PURIFIER for:

• International travel — especially developing countries where sewage treatment may be inadequate
• Urban disasters — flooding, sewage system failures, broken water mains
• Unknown water sources — if you don't know where the water came from, assume the worst
• Areas with human waste contamination — downstream from populated areas, stagnant water near settlements
• After hurricanes or floods — sewage overflow is extremely common

A FILTER is usually enough for:

• North American backcountry — viruses are generally not present in wilderness water sources away from human activity
• Clear-flowing mountain streams — still filter for bacteria and protozoa, but virus risk is low
• Municipal tap water (even during boil notices) — the concern is usually bacteria, not viruses

The rule: When in doubt, purify. If you're not 100% sure the water source is safe from human contamination, use a purifier.

🥇 GRAYL GeoPress (~$90) — PURIFIER

This is a PURIFIER — complete protection.

What it removes:

• 99.99% of viruses (norovirus, rotavirus, hepatitis A)
• 99.9999% of bacteria (E. coli, salmonella, cholera)
• 99.9% of protozoa (Giardia, Cryptosporidium)
• Heavy metals, chemicals (including PFAS), pesticides, microplastics

How it works: Fill the outer container with dirty water, press the inner bottle down through it, drink clean water. Takes about 8 seconds. Dirty water NEVER touches your drinking container — the systems are separate. No cross-contamination.

Specs:

• 24 oz (710 ml) capacity
• 15.9 oz weight
• ~350 presses per cartridge — that's 65 gallons (250 liters)
• Replacement cartridges ~$25-30

Is 65 gallons enough? Do the math: at 3-4 gallons of personal drinking water per day, that's about 20 DAYS of water from one cartridge. For an emergency? That's substantial. For long-term? Stock extra cartridges.

Where I keep my GRAYL: Go bag / BOB, trekking and adventure travel, international trips.

GRAYL GeoPress on Amazon →

🥈 Katadyn BeFree (~$45) — FILTER

This is a FILTER — and I absolutely love it.

What it removes:

• 99.9999% of bacteria
• 99.9% of protozoa (Giardia, Cryptosporidium)
• Does NOT remove viruses

Specs:

• 1.0L collapsible Hydrapak flask
• 2.3 oz weight (ultralight!)
• ~1,000 liters filter life — that's 264 gallons
• Flow rate: 2 liters per minute (FAST)

Why I love the Katadyn BeFree:

It's LIGHT. It CRUSHES DOWN TO NOTHING.

The flexible flask is both the downside and the upside — yes, it could puncture, but it also packs completely flat. I can stuff it in my work backpack or a purse and forget it's there until I need it.

My diabetic daughter keeps one in her purse. Always.

Cleaning is dead simple: Just shake or swish the filter in water. No backflushing, no tools, no complicated process.

Where I keep Katadyn BeFree: EDC bag (with a sillcock key for urban water access), every vehicle, work backpack / purse, backup in every go bag.

I own about 8 of them scattered across all my gear.

Katadyn BeFree on Amazon →

Bonus: 4-Way Sillcock Key (~$8)

The Katadyn is great for cities too. Pair it with a 4-way sillcock key and you can access water from those tamper-resistant commercial building spigots. Schools, office buildings, public facilities — they all have them.

In an urban emergency, that's your water source. Filter it and drink.

4-Way Sillcock Key on Amazon →

What About LifeStraw?

Avoid it. Overrated. Awkward to use. Better options exist for the same price.

A Word on Gear Quality

I focus on buying GOOD gear, not cheap gear.

Cheap gear breaks. Then you replace it. Then it breaks again. You end up spending MORE than if you'd just bought quality from the start.

No judgment if budget is tight — we all start somewhere. But if you can afford better, do it.

Start with ONE GRAYL. ONE Katadyn BeFree. Use them. Then buy more as you go.

Actually USE Your Gear

Seriously — take them out of the boxes. Practice.

Fill them with water. Press. Squeeze. Learn how they work BEFORE you need them.

Don't just toss gear into a kit and forget about it.

(Okay... truth? If you do that, at least keep the instructions WITH them.)

But better is to PRACTICE. Know your gear. Trust your gear. Because in an emergency, you don't have time to figure it out.