You're standing in a sporting goods store, looking at two water filters. Both claim '>99.9% bacteria removal.' One costs $25 and only advertises bacterial protection, the other $50 but also offers virus protection.

Why do we prioritize virus protection while most companies don't offer it at all? And when does this difference actually matter?

When Does Virus Protection Matter?

The good news: If you're drinking tap water in the United States, viruses are rarely a concern. Municipal water treatment does an excellent job removing them.

However, waterborne viruses become a real threat in four specific situations:

1. Backcountry water sources near popular trails – Heavy foot traffic and improper human waste disposal can contaminate streams and lakes.
2. Private wells – Unlike municipal systems, private wells typically lack the disinfection treatment needed to remove viruses.
3. Emergency or disaster situations – Floods, earthquakes, and fires can compromise water infrastructure, allowing viruses into previously safe water supplies.
4. International travel to developing countries – In many regions, inadequate sanitation allows human waste to contaminate drinking water sources.

So here's the question: If viruses are a real problem in these situations, why don't regular filters handle them? And why do manufacturers proudly advertise bacterial filtration but stay silent about viruses?

The answer comes down to one critical factor: size.

The Size Problem: Why Viruses Are Different

There are three main classes of waterborne pathogens, and they exist on wildly different scales:

• Protozoa (Giardia, Cryptosporidium) – Think microscopic amoeba. On the pathogen scale, they're huge at 5-15 micrometers. While extremely dangerous, they're relatively easy to filter out.
• Bacteria (E. coli, Salmonella) – Much smaller at 1-2 micrometers. If a protozoan were the size of a basketball, bacteria would be the size of a marble.
• Viruses (Norovirus, Hepatitis A) – By far the smallest at just 0.02-0.1 micrometers (20-100 nanometers). Using the same scale, viruses would be the size of a grain of sand.

Why size matters: Most filters work like a coffee press—they have a certain pore size and can only capture particles larger than those openings. And this is where viruses become a problem.

The Pore Size Trap

The 0.2 micron (200 nanometer) pore size that most camping filters advertise? It's 7-10 times larger than most viruses. Viruses slip right through it easily.

To catch viruses through mechanical filtration alone, you'd need to use smaller and smaller pores. Here's what that looks like:

• Microfiltration (0.1-10 microns) – Catches bacteria and protozoa ✓ / Misses viruses ✗
• Ultrafiltration (0.01-0.1 microns) – Starts catching some viruses
• Nanofiltration (0.001-0.01 microns) – Catches viruses ✓

But here's the catch: As pores get smaller, several problems emerge:

1. Flow rate drops to a trickle – Water can barely squeeze through tiny pores
2. Filters clog almost immediately – Larger particles quickly block the tiny openings
3. High pressure required – You need pumps or significant suction to push water through
4. Cost skyrockets – Manufacturing sub-micron filtration media is expensive

For portable filters, pure mechanical virus removal simply isn't practical. You'd need heavy pumping equipment and constant filter replacements.

So scientists had to get creative.

The Clever Solution: Electro-Adsorption

Instead of making pores impossibly small, scientists discovered a completely different approach. They found that in normal pH water (the kind you actually encounter), most viruses carry a negative electrical charge.

This meant viruses didn't just need to be caught mechanically—they could be attracted using positively charged filter media, almost like a magnet.

Think of it like fishing:

• Old approach: Use a net with holes so tiny that nothing can escape (slow, clogs easily, impractical)
• Smart approach: Use a larger net, but coat it with fish bait. They latch on to it and get stuck.

With electro-adsorption, even when the pore size is 100 times larger than the virus itself, the positively charged filter media attracts and captures the negatively charged viruses as water flows through.

The result? Fast flow rates, minimal clogging, and effective virus removal—all without requiring impossibly small pores.

ÖKO's Solution: The Best of Both Worlds

At ÖKO, we realized that while electro-adsorption is powerful, combining it with mechanical filtration creates the most reliable protection.

Our approach:

• Electro-adsorptive media to capture viruses through electrical attraction
• ~1 micron mechanical filtration to remove bacteria, protozoa, and larger particles
• Dual-action protection ensures comprehensive removal across all pathogen types

Whether you're trekking through Nepal, relying on a private well, or preparing for emergencies, you can trust that your water is truly safe—not just from bacteria, but from viruses too.