Gear Review—Homemade gravity-fed water filtration system

Lots of people are passionate about their water filtration systems. It seems like an odd thing to hang your hat on, but whatever floats your boat. This is what I care about in order of importance when it comes to gear:

1. Effectiveness
2. Weight
3. Ease of use
4. Durability
5. Dual-use

Where I usually hike, you don’t really have to filter your water if you’re high on the mountain. But after a recent bout with food poisoning (bad sushi), I realized that the convenience is simply not worth the risk. I eventually settled on this homemade system after exploring different methods of filtration.

System components

I use the Sawyer Squeeze as my filter. I bought the components of my gravity system separately, but they now sell a couple of them in the Sawyer Squeeze Hydration Kit. This includes the filter and the inline adapter (the gray nozzle in the picture). If you already have a Sawyer Squeeze, then you can buy the adapter separately. To complete the system, you’ll also need to pick up a bottle coupler, a shut-off hose clamp, and a Platypus Big Zip LP Reservoir.

System cost

All in all, this will run you about $65. That might seem high, but similar systems cost over $100.

For example, check out the Platypus Gravity Works System that’s around double the price of this system and weighs several ounces more (11.5 oz).

My gravity system is a better set-up because it’s modular. That means you can replace outdated or broken pieces when needed. You can also augment the system to suit your environment and needs as they change.

System set-up

This is not very complicated. The Platypus acts as a dirty water bag. You filter directly into clean water bottles.

1. Cut the quick-disconnect hose with a utility knife so it’s just a few inches long. Save the mouthpiece for other uses.
2. Thread the shut-off clamp onto the hose.
3. Thread the hose onto the inline adapter.
4. Screw the adapter into the dirty end of the filter.
5. Screw the coupler onto the clean end of the filter.
6. Tie some string on the Platypus mouth so you can hang the reservoir. I use a mini-carabiner so I can hang it from tree branches.
7. Fill the reservoir with dirty water and hang it anywhere.
8. Close the shut-off clamp on the hose and connect the tube/filter to the reservoir.
9. Screw a SmartWater bottle into the coupler. I actually use two 1-liter Propel bottles (they’re more rigid) with SmartWater sport caps. They fit perfectly into the coupler. Don’t thread it too tightly because the air needs room to escape.
10. Release the shut-off clamp while you fill the bottle.

Here’s what it looks like assembled and in use on the trail. Check out the flow rate. And this comes with zero effort other than filling and hanging the bag.

 

Using this method, the likelihood of cross-contamination is about as close to zero as you can get.

Pros

• It’s stupid easy to use.
• The wide mouth on the Platypus makes it easy to fill with dirty water.
• There is no squeezing and no thin water bags that are prone to failure.
• You don’t have to aim the filter over the water bottle.
• It filters quickly while you’re free to do something else.
• The shut-off allows you to stop the flow while you switch bottles without disconnecting the hose.
• The bottles just hang from the hose. I said it was easy.
• If you have two 1-liter water bottles, then this gives you a carrying capacity of 4 liters if you’re far from the next water source.
• To clean the filter, you just unscrew the Sawyer and backflush it with the SmartWater bottle cap.
• You can clean the reservoir and use it like a Camelbak when you’re out for day hikes. You just need another another quick-disconnect tube and the mouthpiece that came with reservoir.
• If you think it might freeze, you just disconnect the hose from the reservoir and toss the filter into your sleeping bag.

Cons

• More complicated than purification drops
• The complete system (7.62 oz) weighs more than just screwing the Sawyer Squeeze (3 oz) onto a water bottle. But much of that weight is the 2-liter reservoir (3.5 oz) that you’re probably carrying anyway, or at least something similar. That means the weight penalty to turn your squeeze system into a gravity system is around 1 ounce.

Honestly, weight is the only issue here. This gravity-fed filtration system is a model of efficiency. You might wonder why a Sawyer Mini wouldn’t be better since this is an inline system. Well, the Sawyer Mini is really slow, the weight difference is negligible, and the Sawyer Squeeze can be unscrewed from the line and used right on the bottles if need be. That reliability and adaptability make the Squeeze a better choice than the Mini.

If you’re already carrying a filter and a reservoir (and you’re not fond of using bite valves), then why wouldn’t you implement this system? It weighs basically the same and makes everything easier.

Everything you need to make your own

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