Water Filter Systems: AI Market Discovery Index

Tracking how AI platforms recommend water filter systems. This public AI Market Discovery Index is updated monthly since July 2026.

By Mark Huntley, J.D.Growth Strategist & AI Discovery Analyst

5 minutes read

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On this page

01Benchmark Summary
02Current Benchmark at a Glance
03Research Scope and Qualification
04Current Brand Standings
05How to Read the Standings
06Recommendation Coverage Movement
07Largest Increase: Culligan
08Category Leader: Aquasana
09Recommendation Placement Snapshot
10Buyer-Intent Distribution
11Historical Measurement Record
12Evidence and Source Layer

Benchmark Summary

Aquasana led the Water Filter Systems benchmark in August 2026 with 58.9% valid recommendation coverage, up from 55.4% in July 2026. The gap to the next brand, iSpring at 56.9% in August 2026, was 2.0 points.

Culligan recorded the largest coverage increase, rising to 36.6% in August 2026 from 29.6% in July 2026, a move beyond normal month-to-month variation. The largest coverage decline belonged to APEC Water Systems, which fell to 33.9% in August 2026 from 36.6% in July 2026.

The current month fits a two-month series where movement was concentrated. Culligan was the only significant riser, while nine brands were classified as stable. The benchmark began with 800 prompt-surface observations in each month and produced 697 qualified observations in July 2026 and 703 in August 2026 after qualification.

AI recommendation trend

valid recommendation coverage, Jul 2026 to Aug 2026

Aquasana+3.5%
Jul 202655.4%
Aug 202658.9%
iSpring-2.5%
Jul 202659.4%
Aug 202656.9%
PUR-1.9%
Jul 202638.6%
Aug 202636.7%
Culligan+7.0% · beyond normal variation
Jul 202629.6%
Aug 202636.6%
Brita+0.9%
Jul 202635.0%
Aug 202635.9%
APEC Water Systems-2.7%
Jul 202636.6%
Aug 202633.9%
Clearly Filteredno change
Jul 202629.3%
Aug 202629.3%
SpringWell Water-2.1%
Jul 202621.9%
Aug 202619.8%
Berkey-2.7%
Jul 202614.2%
Aug 202611.5%
Pentair-1.6%
Jul 20263.4%
Aug 20261.8%

Current Benchmark at a Glance

Measure	Jul 2026	Aug 2026	Movement
Qualified benchmark observations	697	703	Up 6
Tracked brands	10	10	No change
Qualified surface breadth	6	6	No change
Recommendation-shaped answer share	53.2%	52.8%	Down 0.4 points
Valid recommendation shortlist share	84.1%	88.3%	Up 4.2 points
Leader by valid recommendation coverage	Aquasana (55.4%)	Aquasana (58.9%)	Up 3.5 points

Qualified surface breadth counts the canonical AI/search surface families with at least one qualified observation: ChatGPT, Copilot, Gemini, Perplexity, AI Overviews, and AI Mode. All six families were represented in both months.

For the strategic interpretation of this benchmark, read CiteWorks Studio's analysis of How AI Search Is Recommending Water Filter Systems

Research Scope and Qualification

The public benchmark is narrower than the raw collection universe by design. Brand-level percentages use the qualified observations as the public denominator, not the raw collection.

Research stage	Jul 2026	Aug 2026	What it represents
Source prompt-surface observations	800	800	Raw prompt-surface observations collected
Unique questions	552	607	Distinct questions after de-duplication
Brand / competitor mentions	800	800	Prompts mentioning at least one tracked brand
Relevant observations	797	796	On-topic observations after relevance filtering
Irrelevant observations	3	4	Off-topic observations removed
Qualified benchmark observations	697	703	Public denominator after all qualification

Brand-level percentages use the qualified observations as the public denominator, not the raw collection. See the AI Market Discovery Methodology for the full qualification process.

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Current Brand Standings

This table is the primary current-month benchmark view, sorted by valid recommendation coverage.

Brand	Presence rate	Valid recommendation coverage	Top-three rate	Rank-one rate	Net sentiment
Aquasana	70.4%	58.9%	44.5%	18.9%	0.85
iSpring	62.5%	56.9%	38.4%	12.2%	0.92
PUR	52.6%	36.7%	14.4%	5.1%	0.61
Culligan	52.3%	36.6%	19.5%	3.4%	0.70
Brita	60.3%	35.9%	17.8%	4.3%	0.45
APEC Water Systems	36.7%	33.9%	26.9%	12.1%	0.93
Clearly Filtered	38.0%	29.3%	19.8%	7.1%	0.78
SpringWell Water	23.5%	19.8%	13.1%	6.8%	0.87
Berkey	21.8%	11.5%	5.3%	0.6%	0.48
Pentair	6.5%	1.8%	0.6%	0.1%	0.33

How to Read the Standings

Presence rate is the share of qualified observations where a brand is mentioned at all. Valid recommendation coverage is the share of qualified observations where a brand receives a recommendation that fits the query. Top-three rate is the share where a brand appears in the first three recommended positions. Rank-one rate is the share where a brand is the first recommendation. Net sentiment is the balance of positive over negative mention sentiment. For formulas and denominator rules, see AI Market Discovery Metric Definitions.

Recommendation Coverage Movement

Brand	Jul 2026	Aug 2026	Movement since baseline
APEC Water Systems	36.6%	33.9%	Down 2.7 points
Aquasana	55.4%	58.9%	Up 3.5 points
Berkey	14.2%	11.5%	Down 2.7 points
Brita	35.0%	35.9%	Up 0.9 points
Clearly Filtered	29.3%	29.3%	No change
Culligan	29.6%	36.6%	Up 7.0 points
iSpring	59.4%	56.9%	Down 2.5 points
Pentair	3.4%	1.8%	Down 1.6 points
PUR	38.6%	36.7%	Down 1.9 points
SpringWell Water	21.9%	19.8%	Down 2.1 points

Largest Increase: Culligan

Culligan rose 7.0 points to 36.6% in August 2026 from 29.6% in July 2026, a move beyond normal month-to-month variation. The increase was accompanied by a 10.7-point gain in presence rate to 52.3% and an 8.6-point gain in top-three rate to 19.5%, with 260 positive mentions out of 368 total mentions in August 2026.

Category Leader: Aquasana

Aquasana led the benchmark at 58.9% in August 2026, up 3.5 points from 55.4% in July 2026. While the leader change was within normal variation, Aquasana posted gains in top-three rate, up 11.5 points to 44.5%, and rank-one rate, up 9.1 points to 18.9%. The brand also held the highest presence rate at 70.4% and had 414 valid recommendations out of 703 observations in August 2026. The leadership position was stable.

Recommendation Placement Snapshot

Coverage alone does not show how prominently a brand is recommended. Among the leading brands, placement rates varied meaningfully.

Brand	Aug 2026 top-three rate	Aug 2026 rank-one rate	Jul 2026 top-three rate	Jul 2026 rank-one rate
Aquasana	44.5%	18.9%	33.0%	9.8%
iSpring	38.4%	12.2%	39.6%	15.8%
Culligan	19.5%	3.4%	10.9%	2.3%

Aquasana moved into first position in 18.9% of observations in August 2026, up from 9.8% in July 2026, while iSpring's rank-one rate declined to 12.2% in August 2026 from 15.8% in July 2026. Similar coverage levels can still hide different first-position rates, as seen between Aquasana and iSpring.

Buyer-Intent Distribution

All qualified observations in both months fell into the Brand Recommendation class.

Buyer-intent class	Jul 2026	Aug 2026
Brand Recommendation	697	703
Pricing & Value	0	0
Multi-Brand Comparison	0	0
Total qualified observations	697	703

The current public series measures brand recommendation discovery only and does not yet contain qualified observations in the Pricing & Value or Multi-Brand Comparison classes.

Historical Measurement Record

This is an evergreen benchmark URL. New measurements are added to the same report.

Measurement	Qualified observations	Coverage leader	Leader coverage	Largest coverage movement
Jul 2026	697	Aquasana	55.4%	Baseline (no prior period)
Aug 2026	703	Aquasana	58.9%	Culligan, Up 7.0 points

Evidence and Source Layer

The benchmark is built from prompt-level observations that retain the query, AI/search surface, answer, brand outcome, recommendation placement, sentiment, and, where exposed, citations or attributable evidence sources. Source presence is evidence about the information environment. It is not automatically proof that the source caused the recommendation.

Scope Boundaries

This public benchmark does not measure market share, attributable sales, every possible AI response, organic-search ranking, social mention volume, or private and sponsored channels. A metric movement alone does not establish causality.

About This Benchmark

The LLM Authority Index AI Market Discovery Index tracks how brands appear across major AI and search surfaces through structured, prompt-level observation. Canonical research links:

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