When you’re out in the wilderness and need a reliable water source, gravity water filters are some of the best tools to carry. These systems require no pumping, are lightweight, and are capable of filtering large volumes of water while you’re setting up camp or resting. Based on ease of use, filtration speed, weight, and filter lifespan, here are the best gravity water filters for backpacking that I’ve tested and researched.
What to Look for in a Backpacking Gravity Water Filter
- Weight: You want a system that’s lightweight and compact, so it doesn’t weigh down your backpack.
- Filter Capacity: How much water it can filter in one go, and the lifespan of the filter.
- Flow Rate: Some filters work faster than others, which is important when you need water quickly.
- Filter Type: Most gravity filters use hollow fiber membranes or activated carbon to filter out bacteria, protozoa, and other contaminants.
- Ease of Setup: Look for a system that’s easy to hang and doesn’t require constant attention.
Best Gravity Water Filters for Backpacking
1. Platypus GravityWorks 4L Water Filter System
Best For: Fast filtering and large water capacity
- Weight: 11.5 oz (326 g)
- Filter Life: 1,500 liters
- Flow Rate: 1.75 liters per minute
- Capacity: 4 liters (available in 2L and 6L options)
The Platypus GravityWorks is often regarded as the best gravity water filter for backpackers, thanks to its fast flow rate and large 4L capacity. It can filter up to 1,500 liters before needing a replacement, and its 1.75 L/min flow rate is perfect for filling water bottles or hydration packs quickly. The system is easy to set up, with two clearly labeled bags for dirty and clean water, and it’s simple to hang from a tree or other structure.
- Pros: Fast flow rate, large capacity, easy setup.
- Cons: Slightly heavier than some other options.
2. Sawyer Gravity Water Filtration System
Best For: Lightweight, affordable solution for solo or small group use
- Weight: 8.5 oz (240 g)
- Filter Life: 100,000 gallons (can be backflushed for longevity)
- Flow Rate: 1 liter per minute
- Capacity: 1 or 2 liters
The Sawyer Gravity System uses the Sawyer MINI filter, known for its incredible lifespan and portability. The system itself is lightweight, making it ideal for solo backpackers or small groups. While the flow rate is slower than some other options (about 1 liter per minute), its small size and ease of use make it a solid choice for ultralight backpackers. Plus, with a 100,000-gallon filter life, you won’t need to replace the filter anytime soon.
- Pros: Lightweight, durable filter, very affordable.
- Cons: Slower flow rate, smaller capacity.
3. Katadyn BeFree Gravity 3.0L Water Filtration System
Best For: Ultralight hikers who need speed and simplicity
- Weight: 6.8 oz (193 g)
- Filter Life: 1,000 liters
- Flow Rate: Up to 2 liters per minute
- Capacity: 3 liters
The Katadyn BeFree Gravity system is one of the lightest and most compact gravity filters available, making it a favorite for ultralight hikers. With a fast flow rate of up to 2 liters per minute, it can fill bottles and hydration packs quickly. The EZ-Clean Membrane filter is easy to clean in the field, and it filters out bacteria, protozoa, and other harmful microorganisms. Its smaller 3L capacity is perfect for individuals or small groups, and the whole system packs down small.
- Pros: Very lightweight, fast flow rate, easy to clean.
- Cons: Lower filter lifespan compared to some other systems.
4. LifeStraw Flex with Gravity Bag
Best For: Versatility and budget-conscious backpackers
- Weight: 6.9 oz (196 g)
- Filter Life: 2,000 liters (carbon filter lasts 100 liters)
- Flow Rate: 1 liter per minute
- Capacity: 1 or 3 liters
The LifeStraw Flex is a highly versatile system that combines the LifeStraw Flex filter with a gravity bag. It’s an affordable solution for backpackers looking for a lightweight, easy-to-use filter that can also be used as a personal straw filter or inline with hydration packs. The system filters bacteria, protozoa, and reduces heavy metals, chemicals, and chlorine. The carbon filter improves taste but only lasts for 100 liters (though the main filter lasts for 2,000 liters).
- Pros: Affordable, versatile, includes carbon filter for better taste.
- Cons: Slower flow rate, shorter carbon filter lifespan.
5. MSR AutoFlow XL Gravity Filter 10L
Best For: Large groups or basecamp setups
- Weight: 12.5 oz (354 g)
- Filter Life: 1,500 liters
- Flow Rate: 1.75 liters per minute
- Capacity: 10 liters
The MSR AutoFlow XL is the ideal choice for large groups or when you’re setting up a basecamp. With a massive 10-liter capacity, it’s perfect for filtering water for a group all at once. Despite its larger size, the filter has a decent flow rate of 1.75 liters per minute, and the filter is designed to last for 1,500 liters. It uses a hollow fiber membrane, which is effective at removing bacteria, protozoa, and particulates.
- Pros: High capacity, great for large groups, durable.
- Cons: Heavier and bulkier compared to other options.
Comparison Table: Best Gravity Water Filters for Backpacking
| Brand | Weight | Capacity | Flow Rate | Filter Life | Best For |
|---|---|---|---|---|---|
| Platypus GravityWorks 4L | 11.5 oz | 4L | 1.75 liters/min | 1,500 liters | Large capacity, fast filtering |
| Sawyer Gravity System | 8.5 oz | 1-2L | 1 liter/min | 100,000 gallons | Ultralight, long filter lifespan |
| Katadyn BeFree 3.0L | 6.8 oz | 3L | Up to 2 liters/min | 1,000 liters | Lightweight, fast setup |
| LifeStraw Flex | 6.9 oz | 1-3L | 1 liter/min | 2,000 liters | Versatile and budget-friendly |
| MSR AutoFlow XL 10L | 12.5 oz | 10L | 1.75 liters/min | 1,500 liters | Large groups and basecamp setups |
Key Factors to Consider
1. Weight and Packability
For solo or ultralight backpackers, weight is everything. Systems like the Katadyn BeFree or Sawyer Gravity System are perfect for minimizing your pack’s weight.
2. Filter Capacity and Lifespan
If you’re planning a longer trip or want a filter that can handle group use, the Platypus GravityWorks or MSR AutoFlow are better suited due to their higher capacity and long filter life. For ultralight hikers, Katadyn BeFree offers a good balance between weight and lifespan.
3. Flow Rate
When you’re setting up camp and need water quickly, having a fast flow rate matters. The Katadyn BeFree and Platypus GravityWorks are great for speedy filtration, while the Sawyer Gravity System trades speed for durability and weight savings.
4. Ease of Maintenance
Systems like the Platypus GravityWorks and Katadyn BeFree are known for their easy backflushing or cleaning methods, ensuring your filter stays unclogged during longer trips.
Final Thoughts
Choosing the best gravity water filter for backpacking depends on your specific needs—whether it’s weight, filtering speed, or capacity. If you’re looking for an all-around high performer, the Platypus GravityWorks 4L is hard to beat for its balance of speed and capacity. For those who need something more compact and ultralight, the Katadyn BeFree is a top choice, while the Sawyer Gravity System is ideal for budget-conscious solo hikers. If you’re traveling with a group, the MSR AutoFlow XL is perfect for large-scale water filtration.
Whatever your needs, these gravity filters will provide you with safe, clean water without the hassle of pumping, making them invaluable tools for your backpacking adventures.