Negative Keywords: The Fastest Fix for Wasted Ad Spend

Open your Google Ads search terms report right now. If you run a plumbing company, there's a decent chance you've paid for clicks from searches like "plumber salary," "free plumbing course," or "DIY fix leaking pipe under sink."

None of those people will ever book a job. You paid for their curiosity.

The Leak You Can't See in the Dashboard

Your campaign dashboard shows clicks, impressions, and average CPC — and it can all look healthy while the budget quietly bleeds. That's because the dashboard shows the keywords you bid on. The search terms report shows what people actually typed — and with phrase and broad match, Google stretches your keywords to cover searches you never asked for.

The gap between those two lists is where wasted spend lives.

What a Negative Keyword Actually Does

A negative keyword tells Google: never show my ad for searches containing this term. It's the only lever in Google Ads that works by subtraction — instead of paying more to reach the right people, you stop paying for the wrong ones.

You can add negatives at three levels: a single ad group, a whole campaign, or an account-level list you share across every campaign. That last one is the workhorse — build it once, and every future campaign inherits the protection.

The 15-Minute Weekly Routine

1. Open the search terms report, set the range to the last 7 days.
2. Sort by cost, highest first — always work the expensive mistakes before the cheap ones.
3. For each term, ask one question: would this person pay us? Not "is this related to plumbing" — would they pay.
4. If the answer is no, add the offending word as a negative at the right level: one-off weirdness goes to the campaign, universal junk goes to the shared list.
5. Stop at 15 minutes. Consistency beats thoroughness — a short pass every week outperforms a heroic cleanup every quarter.

The Starter List for Local Service Businesses

Almost every local service business benefits from blocking searches containing: free, cheap, DIY, how to, salary, jobs, hiring, career, course, training, certification, license, school. These are researchers, job seekers, and students — not customers.

When NOT to Add a Negative

Two cautions. One bad click is not a pattern — block the term after it shows up repeatedly, not after one stray impression. And be careful with words that overlap buyer intent: someone searching "water heater replacement cost" is often a real customer doing real comparison shopping. Blocking "cost" everywhere would throw out buyers with the bargain hunters.

Every Blocked Dollar Goes Back Into the Math

If you've read our budget-math reality check, you know the equation: your budget only works when clicks come from people who can become jobs. Negative keywords don't just reduce waste — they raise the percentage of your spend that's even eligible to convert.

If you'd rather have someone run this routine for you every week — that's literally what we do.