Air & Drain Works, a plumbing company in our example market, San Antonio, advertises "$39.99 Drain Cleaning." It's a real offer, and it sits on their site. Now imagine a different plumber whose site still shows a $39.99 coupon from last spring, with no expiration date, on a page nobody has opened since. Turn on AI Max, and Google can read that page and write the price into a fresh ad for this afternoon's searches.
That's the risk this chapter is about. AI Max is Google's newest way to automate Search campaigns, and it's the last thing a plumbing account should switch on. When it does go on, it needs a fence around it, because it writes from your website, and plumbing websites are full of prices.
AI Max Gives Google Three Jobs a Plumber Did by Hand: the Searches, the Words and the Page
Everything in Chapters 5 through 8 was a plumber's decision: which searches to buy, what the ad says, which page the click lands on. Switch on AI Max and Google takes over all three in one move:
- Search term matching lets the ad show for searches past the keywords you wrote. In practice it behaves like broad match, with Google deciding what's related.
- Text customization writes new headlines and descriptions using text from your website and your existing ads.
- Final URL expansion lets Google send the click to whichever page on your site it judges a better fit than the one you picked.
Start a Search campaign today and Google has already ticked the AI Max box for you, and the generated text and Google-picked pages ride along unless you untick them. The same page says these features need Smart Bidding that learns from conversions to work well.
That last point decides where AI Max belongs. Isolation runs on hand-set bids and exact match keywords, so AI Max has no place there; Chapter 9 switched it off at launch. Exploration, the broad match campaign that bids toward a cost per booked job from Chapter 6, is the only campaign in this build where AI Max fits, and only after it has run long enough to know what a booked job costs. One practical note from Google's FAQ: AI Max can't yet be managed through the Google Ads API, so whoever turns it on does it in the regular Google Ads screens, and anyone running the account through automated tools should hear about it first.
7 of 12 Plumbing Sites We Checked Publish a Drain Price. AI Max Reads All of Them.
The text customization feature draws on your website for raw material. So the question isn't whether AI Max writes well. It's what your website would hand it.
We read the sites of 12 plumbing and multi-trade companies in the example market. Here's what was sitting on them:
- Drain prices on 7 of 12: $39.99, $45, $79, $89, $99 on two sites, and $299 for a jetting job.
- Dollar coupons on 8 of 12. Several had no expiration date at all, or an expiration that left out the year.
- Fee amounts on 3 of 12. One site listed three different amounts for the same visit on different pages: $100, $60 and $69.
- Copy written for another city on 4 of 12. Fine print, testimonials or service text that named a different market. One San Antonio ad landing page told visitors how to keep "your Dallas-Fort Worth home cool."
- Maintenance plan prices on 7 of 12, from $12.95 to $29.99 a month across tiers and pages.
Every one of those is a line a model could lift into a headline. The undated coupon becomes a current offer. The $60 fee from an old page contradicts the $100 fee on the new one, and Chapter 4 showed what an ad-to-page mismatch costs. The other city's fine print ends up in an ad for San Antonio. None of it requires AI Max to make anything up; it only has to read what's already there.
Final URL expansion adds a second risk on top of the text. At least one of the 12 sites runs its best drain offer on its home and specials pages, while the ad for that offer points to a drain cleaning page with no price on it. With expansion on, Google can choose the specials page for the click, and then the homeowner lands on a wall of coupons instead of the job they searched for.
Plumbing sites make this harder than most because their offers move with the seasons. A winterization special in December, a water heater discount in spring, a drain coupon that runs all year: each gets added to the site, and too often nobody takes the old one down. AI Max reads every one of them as current, whatever date sits on the page.
So the first fence isn't a setting. It's the website. Before AI Max goes on, walk the site the way Google will: every coupon, every fee, every price, every page that mentions a city you don't serve. Delete what's expired, fix what conflicts, and date what stays.
A "$" Term Exclusion Lets "$39.99 Drain Cleaning" Through. A Messaging Restriction Doesn't.
The second fence lives in the campaign settings, under a name Google calls text guidelines:
- Term exclusions: a banned-word list, 25 entries long at most. Case doesn't matter. Language does: banning "free" leaves "gratis" open in a Spanish ad.
- Messaging restrictions: a banned-idea list, 40 entries long at most, written as sentences. These follow the ad into every language.
The obvious move for a plumber worried about prices is to add "$" as a term exclusion. Google says outright that it won't work. A term exclusion can't stop a priced asset from being generated, and Google's own example is that "$" won't block a line like "Shoes for less than $50." The fix Google names is the messaging restriction "Don't generate assets with prices."
The language rule matters if you followed Chapter 9 and built a Spanish ad group. Banning "free" leaves "gratis" open, so write the Spanish versions of your exclusions as well. Messaging restrictions don't need translating; Google applies them to every language in the campaign.
Google also suggests writing restrictions with an example inside them, because they work better that way. For a plumbing account: "Don't generate assets with prices, e.g. $39.99 drain cleaning or $299 jetting." And it warns that a rule like "don't include any pricing information" may be broader than you mean, since it can strip out promotions you actually want. Google also flags restrictions that are too vague to follow. Its example is a rule that just reads "25% off $60": the model can't tell whether that phrase is required, banned, or partly banned. A plumber writing "$50 off $250" into a restriction has the same problem. Say what you mean in a full sentence: "Don't mention the $50 off $250 offer," or "Only mention discounts that appear on the specials page today."
A Plumber's Text Guidelines, Written Before AI Max Is Switched On
Here's how a plumbing account fills in both lists before AI Max touches a campaign. Adjust it to your own site and your own offers.
Term exclusions (up to 25):
- The names of cities and towns your site mentions but your trucks don't serve.
- "Free," if you don't offer a free estimate or free service call right now.
- "Guaranteed" and "warranty," unless your page states the terms.
- Competitor and franchise names, so a stray line can't mention them.
- "Cheap," if that's not how you want the shop described.
Messaging restrictions (up to 40):
- Don't generate assets with prices, e.g. $39.99 drain cleaning or $299 jetting.
- Don't mention trip, service call or diagnostic fee amounts, e.g. $60 or $100.
- Don't claim 24/7 or emergency service, if your phones aren't staffed around the clock.
- Don't mention financing rates or terms.
- Don't promise same-day service.
Then add the URL exclusions from Chapter 10, so final URL expansion can't send a click to the coupons page, the careers page or a blog post. Google lets you check the text assets AI Max has generated, so look at them in the first week and again a few weeks later. A guideline you didn't think of will show up there first. Read the generated headlines the way a homeowner would: does every price match today's offer, does every promise match the page, does every town name match the service area? Anything that fails becomes a new exclusion or restriction. If the same kind of problem keeps coming back after you've fenced it twice, switch text customization off and keep AI Max's wider matching only, or switch AI Max off entirely and let Exploration run as it was.
Finally, treat AI Max like any other change: on the Exploration campaign only, after the 30-conversion gate, measured on booked jobs. Google makes that easier than it used to. Its help page describes AI Max experiments that split traffic 50/50 between the campaign as it is and the same campaign with AI Max on, and lets you switch the wider matching or the generated text on or off ad group by ad group inside the test. A plumbing account can try AI Max on drain cleaning, where the site's prices are clean, while water heaters stay out of it.
Two more details from Google's own FAQ. Your negative keywords still apply with AI Max on, so the list from Chapter 5 keeps doing its job. And switching AI Max off later turns off every AI Max feature at once, including any brand exclusions set inside it, so recheck brand settings if you ever back it out. If booked jobs per dollar hold or improve after it goes on, keep it. If the calls get stranger, it's reaching too far.
Setting those fences and watching what AI Max writes is part of what our Google Ads management team does before it touches a plumbing account's ads.
Next: Google Asks Emergency Plumbers to Disclose Call-Out Fees. Most Sites We Read Didn't Give a Number.
Fees came up twice in this chapter: on the sites, and in the reviews. Chapter 14 covers emergency calls and the fees that come with them, including Google's own rule on disclosing call-out charges.
This chapter is part of Google Ads for Plumbers, our sixteen-chapter guide for plumbing companies anywhere in the US.
