Open any piece of AI-generated content and count the words that carry no meaning on their own: the, is, of, and, to, a, in, that. On average, these "water words" — also called stop words — make up 40 to 60 percent of AI text.
That's a problem. Not because stop words are inherently bad, but because AI models systematically overuse them as connective tissue, bloating sentences without adding substance.
What Counts as a Water Word?
Water words are grammatical function words that carry structural meaning but no content meaning:
Articles: the, a, an Prepositions: of, in, on, at, to, for, with, by Conjunctions: and, but, or, so, because, although Auxiliary verbs: is, are, was, were, has, have, had, will, would Pronouns: it, this, that, these, those, they, we
In a well-written 500-word article, you'd expect about 200 of these — 40%. In a typical AI-generated equivalent, the count is often 280–310, or 56–62%.
Why High Water Density Hurts SEO
Search engines use statistical models to assess content quality. High stop word ratios are one signal among many that correlate with thin content:
TF-IDF dilution: TF-IDF (Term Frequency-Inverse Document Frequency) measures how important a keyword is in your document relative to a corpus. When water words crowd out content words, your actual topic keywords get diluted — their TF scores drop even if you mention them frequently.
Passage indexing: Google now indexes individual passages, not just pages. A passage stuffed with connector phrases and filler is less likely to be surfaced as a featured snippet or AI Overview answer.
Readability signals: High water word density often correlates with low information density — which modern ranking algorithms can detect via perplexity-based language model scoring.
The Fluency Trap
AI models are optimized for fluency — text that reads smoothly and sounds natural. Fluency and information density are often in tension. To produce fluent transitions, the model inserts phrases like:
- "It is important to note that..."
- "In the context of this discussion..."
- "As we can see from the above..."
- "It should be mentioned that..."
These phrases are pure water. They read naturally but communicate nothing. A reader scanning your article loses time; a search engine's quality classifier sees low-density prose.
How to Measure Water Density
Water density = stop words ÷ total words
Under 40% — excellent. Your content is dense with meaningful terms. 40–50% — acceptable for most content types. 50–60% — AI-like filler level. Editing needed. Over 60% — significantly diluted. Major rewrite recommended.
TextPurify calculates water density automatically and highlights stop words in orange, so you can see which sentences are carrying weight and which are padding.
How to Reduce Water Words
Cut the setup phrases
Instead of: "In order to fully understand the concept, it is necessary to first consider..." Write: "To understand this, consider..."
Use active voice
Passive constructions multiply water words. "It was decided by the team that..." becomes "The team decided..." — four water words removed.
Compress transitions
"With all of this in mind, we can now move on to discussing..." becomes "Next:" or nothing at all.
Delete hedge words
"somewhat," "rather," "quite," "generally," "typically," "often" — unless you're making a precise claim that requires qualification, cut them.
The Right Amount of Water
Zero stop words isn't the goal. Text without function words isn't English — it's a keyword list. The goal is purposeful density: every word, including the structural ones, should earn its place.
A water density of 35–45% is the sweet spot for most professional content. Below 35%, prose often feels choppy or technical. Above 50%, you're writing filler.
TextPurify's water word detector highlights stop words in real time so you can spot and fix density problems before publishing.