Gravity-Feed Water System

A bag of contaminated water hangs above a filter. Clean water drips into your container while you sleep.

When it matters

• Shelter-in-place at basecamp with questionable water source: manual boiling taxes fuel supplies and time. Gravity system processes overnight—1–3 liters per 12 hours depending on sediment.
• Group evacuation to rural area: 4–5 people, limited boiling fuel, large volume needed. Gravity system handles continuous processing with zero fuel cost.
• Post-disaster relief station: spring nearby but murky, hundreds of gallons needed. Multiple gravity systems running in parallel do bulk processing.

What it does

• Batch water purification when fuel for boiling is limited or zero
• Overnight processing—fill in evening, drink clean water at dawn
• Multi-liter capacity for groups (not single-person EDC)
• Non-obvious: pre-filtering sediment before relying on backup AquaStraw (extends straw life)

Built to last

Requires hanging setup and time. Doesn't remove all viruses (depends on filter grade). Slow—1–3 liters per 12 hours. Not portable for transit.

Where it fits your kit

Home 72-Hour layer. Collapsible Water Bladder 10L: Bladder is top chamber (fill point); system hangs and gravity-feeds through filter into container. AquaStraw Field Filter: Straw for emergency direct-draw if system isn't deployed yet; or for redundant filtration.

Specs

• Materials: Polyester fabric with gravity filter cartridge
• Flow rate: 1–3 liters per 12 hours (depends on sediment load)
• Filter type: Gravity-fed activated carbon and mechanical filter
• In the box: 1x complete system with filter cartridge

Field notes

• Pre-filter water through cloth before pouring into top chamber—sediment will clog the gravity filter fast and reduce flow to nothing.
• Hang from hook or branch at least 2 feet above your collection container. Higher = faster drip.
• If flow stops completely, cartridge is saturated. Backflush gently (reverse water flow) or replace cartridge.

FAQ

Q: How clean is the water? Removes bacteria, protozoa, particles. Some viruses pass through depending on filter grade—boiling is still safer if possible. Never use gravity alone for unknown contamination.

Q: How long does one filter cartridge last? It filters far more water from clear sources than from muddy ones. Silty water clogs it faster, so pre-filter through cloth. Always have spare cartridge.

Q: Can I use this in winter? Flow slows dramatically below freezing. Ice forms inside bag and clogs filter. Not practical in true winter unless you keep the bag wrapped and warm.

Covered by the optional Watchtower Guarantee.

Orders are placed with our fulfilment partner within 1–3 business days and ship tracked from overseas warehouses. Transit to the US is typically 5–11 days. Standard shipping is $7.95, free at $149 in qualifying items. We accept physical-item returns. You pay return postage. Refunds are issued within 45 days of receiving your return. Monthly subscriptions and digital products are non-refundable. Full shipping & returns terms.