A filter's price tag says little on its own. Divide it by the gallons the brand says it's rated for and you get cost per gallon, which is how we rank. Where a system has parts with different ratings, we use the shortest-lived part. Ratings and what each filter removes are the brand's claims, quoted on each product page.
Replacement elements 5
| Rank | Filter | $ / gallon | Price | Rated | Brand's wording |
|---|---|---|---|---|---|
| #1 | Survivor Filter Straw Ultra Filter Replacement Survivor Filter In stock | $0.0006 | $16.95 | 26,417 gal | "can be re used up to 100,000 liters (26,417 gallons)" Note: Replacement Ultra Filter element only |
| #2 | SURVIVOR FILTER™ Pure 10K - Replacement Chlorine Filter Survivor Filter In stock | $0.0080 | $80.00 | 10,000 gal | "Capacity: 10,000 gallons (37, 854 liters)" Note: Replacement chlorine filter for treated tap water |
| #3 | Survivor Filter Straw Carbon Filter Replacement Survivor Filter In stock | $0.0566 | $14.95 | 264 gal | "Can be re used up to 1,000 liters (264 gallons)" Note: Replacement carbon element only |
| #4 | SURVIVOR FILTER™ Max - Replacement Stage 1 Fluoride Filter Survivor Filter In stock | $0.0588 | $100.00 | 1,700 gal | "Capacity: up to 1,700 gallons" Note: Replacement stage 1 fluoride filter for treated tap water |
| #5 | Replacement Filter for Active All Terrain and Americana Ultra Light Water Bottle, 2-Pack Survivor Filter In stock | $0.35 | $35.00 | 100 gal | "Long lasting Filter: 426 refills, 100 gallons or 3 months of daily use" Note: Replacement filter |
Straws, squeeze and personal 5
| Rank | Filter | $ / gallon | Price | Rated | Brand's wording |
|---|---|---|---|---|---|
| #1 | Puribag Micro - Mini membrane water filter Uncharted Supply Co In stock | $0.0174 | $22.99 | 1,321 gal | "Filters up to 5,000 litres of water" Note: 5,000 L converted at 3.785 L per gallon |
| #2 | LifeStraw Peak Series Straw Echo-Sigma In stock | $0.0260 | $25.99 | 1,000 gal | "Long-lasting membrane microfilter will last up to 4,000 L (1,000 gallons) of water" |
| #3 | LifeStraw SIP Echo-Sigma In stock | $0.13 | $34.95 | 264 gal | "the filter lasts up to 1,000 liters – over a year of daily use" Note: 1,000 L converted at 3.785 L per gallon |
| #4 | SURVIVOR FILTER™ Active All Terrain Filtration Bottle & Carrier System Survivor Filter In stock | $0.50 | $49.95 | 100 gal | "1x Active All Terrain Filter, 100-Gallon Capacity" |
| #5 | Frontier Pro Ultralight Water Filter - Green Line (GRN-III-50-T) Legacy Food Storage In stock | $0.60 | $29.99 | 50 gal | "Certified filtration for 50 gallons (over 180 L)" |
Pumps and bag purifiers 5
| Rank | Filter | $ / gallon | Price | Rated | Brand's wording |
|---|---|---|---|---|---|
| #1 | Puribag Pro - Membrane Filter Kit Uncharted Supply Co In stock | $0.0227 | $29.99 | 1,321 gal | "providing up to 5,000 liters of treated water, depending on water turbidity" Note: 5,000 L converted at 3.785 L per gallon |
| #2 | Puribag Pro Portable Water Purification System Uncharted Supply Co In stock | $0.0492 | $64.99 | 1,321 gal | "The PRO SYSTEM amplifies the Puribag's capacity from up to 120 liters to an impressive 5,000 liters" Note: 5,000 L converted at 3.785 L per gallon |
| #3 | Puribag Pro Kit - Portable 4-in-1 Water Filtration System Uncharted Supply Co In stock | $0.0757 | $99.99 | 1,321 gal | "The PRO KIT amplifies the Puribag's capacity from up to 120 liters to an impressive 5,000 liters" Note: 5,000 L converted at 3.785 L per gallon |
| #4 | SURVIVOR FILTER PRO™ Portable Water Filter Pump Survivor Filter In stock | $0.15 | $77.95 | 528 gal | "The Carbon Filter can be reused up to 2,000 liters" Note: Shortest-lived part (2,000 L, about 528 gal). Pre-filter and Ultra Filter are rated to 100,000 liters |
| #5 | Puribag Monster Bug Out 4-Pack Water Purification System Uncharted Supply Co In stock | $1.26 | $159.99 | 127 gal | "Enough capacity to treat up to 480 liters of safe, drinkable water" Note: 480 L converted at 3.785 L per gallon |
Tap and inline filters 1
| Rank | Filter | $ / gallon | Price | Rated | Brand's wording |
|---|---|---|---|---|---|
| #1 | SURVIVOR FILTER™ Max, 2-Stage Fluoride and Chlorine In-Line Home Filter Survivor Filter In stock | $0.0400 | $200.00 | 5,000 gal | "the Fluoride Filter that removes fluoride by 95% and has a 5,000 gallon (18, 927 liters) capacity" Note: Shortest-lived stage. The brand rates the All Tap stage to 8,000 gallons. For treated tap water |
Gravity and countertop 4
| Rank | Filter | $ / gallon | Price | Rated | Brand's wording |
|---|---|---|---|---|---|
| #1 | Big Berkey Stainless Steel Drip Filter System - 2 Black Berkey Filters (approx. 6000 gal.) Legacy Food Storage In stock | $0.0645 | $387.00 | 6,000 gal | "These high capacity filters provide up to 3000 gallons per filter, and 2 are included" Note: Two filters at up to 3,000 gallons each |
| #2 | Royal Berkey Stainless Steel Drip Filter System - Includes 2 Black Berkey® Filters (approx. 6000 gal.) Legacy Food Storage In stock | $0.0717 | $430.00 | 6,000 gal | "Black Berkey® high capacity filters with an approximately 3000-gallon capacity each (approx. 6000 gallons total)" Note: Two filters at about 3,000 gallons each, per the listing |
| #3 | Frontier Max Filter System Virus - Red line (RED-IV-120) Legacy Food Storage In stock | $0.42 | $49.99 | 120 gal | "provides up to 120 gallons of virus, bacteria, and cyst removal" |
| #4 | Puribag 120L System Uncharted Supply Co In stock | $1.42 | $44.99 | 32 gal | "Enough capacity to treat up to 120 liters of safe, drinkable water" Note: 120 L converted at 3.785 L per gallon |
Store water first
Ready.gov's baseline is one gallon per person per day for several days (ready.gov/water). A filter is the backup. Work out your gallons in the water table, or browse water storage.
Questions people ask
What is the cheapest water filter per gallon?
Today: Survivor Filter Survivor Filter Straw Ultra Filter Replacement at $0.0006 per rated gallon.
Do tap-water filters work on lake or stream water?
No. Filters made for treated city water (chlorine, fluoride) are not backcountry purifiers. Check the brand's stated use and what it removes.
Why use the shortest-lived part?
If a pre-filter or pad needs replacing first, that sets the real cost per gallon unless you buy replacements. We note this on each product.