We Put E. coli Pond Water Through the "Best" Gravity Filters...

Overview

The video tests five gravity-filter elements on heavily contaminated local pond water to see whether they remove E. coli and total coliform bacteria. The pond sample contained 326 E. coli CFU per 100 mL and more than 2,420 total coliforms per 100 mL.

The tests did not measure virus removal, and the results cannot establish that any filter alone makes unsafe water safe to drink. The authors also caution that test limits, sample handling, and possible filter bypasses affect what can be concluded.

Pond-Water Test Results

Filter element E. coli after filtering Total coliforms after filtering Review’s interpretation Alexapure Pro 0 detected 0 detected Most promising overall; strongest supporting pathogen-test data British Berkefeld Ultra Sterasyl 0 detected 0 detected Promising in this test, but less comprehensive pathogen testing British Berkefeld Ultra Fluoride 0 detected About 78.8 per 100 mL Some bacteria passed through Purewell K-series 0 detected Above the test’s detection limit Some coliforms passed through Patriot Pure Nanomesh About 63.1 per 100 mL Above the test’s detection limit Failed both bacterial tests

A zero result means none were detected in the sample; it does not prove a filter achieved the reduction needed for reliable protection. The pond’s E. coli concentration was too low to demonstrate the EPA’s six-log bacterial reduction target, while the coliform concentration exceeded the test’s measurement range.

Alexapure Pro: Key Features and Experience

Strengths

• The only system in the comparison described as having third-party testing to the NSF P231 water-purifier protocol, covering bacteria, viruses, and cysts. The review says its published results met the protocol’s reduction targets: six logs for bacteria, four for viruses, and three for cysts.
• In the pond test, no E. coli or total coliforms were detected after filtration.
• Also performed well in the channel’s earlier tap-water testing, removing most tested contaminants completely or nearly completely. Lithium, strontium, and fluoride were less effectively reduced.
• Filtered water was described as clean-tasting and smelling.
• Easy to set up, with a sturdy stainless-steel faucet and 304 stainless-steel construction. The 2.18-gallon clean-water tank was considered adequate for ordinary use.
• Compact and not especially heavy when disassembled, making it portable.
• Filtration speed was considered suitable for daily use, though waiting for water on demand takes patience.

Limitations and Costs

• The manufacturer recommends a 200-gallon life per filter; the reviewers would not exceed it, especially with unsafe source water.
• The review says it is not always clear how much of the stated 200-gallon filter life was covered by P231 testing.
• Around $400 for a two-filter system, slightly above average among the filters compared. The reviewers were unable to obtain a discount.
• One-year warranty; estimated ongoing cost with two filters used in parallel was about $245 per year, around average.
• Despite its test results, Alexapure’s manual advises against using it by itself on microbiologically unsafe or unknown-quality water without prior or subsequent disinfection, specifically recommending chlorine dioxide.

Rating: 3.83/5, fourth-highest overall in the channel’s comparison. That score covers tap-water filtration, ease of use, and cost—not microbial reduction—so the reviewers still rank it first among the products discussed for non-potable water.

Comparisons and Other Findings

• British Berkefeld Ultra Sterasyl also produced zero detectable bacteria in the pond test. It has NSF certification for cyst reduction and third-party bacterial data, but the reviewers say the available bacterial result is four-log reduction rather than the six-log target, with no comparable virus result.
• Ultra Fluoride has a stated 0.9-micron rating, which the reviewers say is not small enough to reliably capture bacteria. It is certified for cyst removal and has third-party bacterial-reduction results, but some bacteria remained in this test.
• Purewell K-series includes a hollow-fiber ultrafiltration membrane rated at 0.01 microns, but coliforms remained. The reviewers also note inconsistent bacterial-reduction claims on its website.
• Patriot Pure Nanomesh had strong prior tap-water results and NSF-related certifications, but its product description’s claims about trapping microbes were not backed by germ-removal test results the reviewers could find. It failed both bacterial tests, so they do not recommend it for microbiologically unsafe water, despite ranking it highly for municipal tap water.
• Water clarity was a poor indicator of microbiological safety. Alexapure produced the clearest water, at 0.29 NTU from an initial 9.46 NTU. Nanomesh was second-clearest despite failing both bacterial tests, while Ultra Sterasyl—one of the filters with no detectable bacteria—had the highest final turbidity, 6.42 NTU. The authors’ conclusion: clear water is not necessarily safe water.

Verdict

The reviewers’ top choice among these gravity filters for non-potable water is Alexapure Pro, based on its pond-test results and the most comprehensive pathogen testing discussed. Ultra Sterasyl also looks promising from the pond test, but has less complete supporting evidence. The video strongly advises not relying on a gravity filter alone for unsafe or unknown-quality water; combine filtration with an appropriate disinfection method whenever possible.

Speaker perspectives: The video presents one narrator’s testing and assessment; no separate speakers offer differing views.