A trade with few searches punishes broad targeting harder than a crowded one

TL;DR

• Google Ads can work for a septic company when the septic campaign is drawn around the areas that have tanks, has its own budget, and keeps its keywords close to the word septic. Run inside a plumbing campaign drawn around a metro mostly on sewer, on broad match, it can spend much of its budget on homes that can't use septic service. In the Phoenix account below, septic spend moved out of the sewer-only center once its map was redrawn.
• Our reading of why: Maximize conversions "will try to fully spend your average daily budget", and broad match adds "additional related searches". When the real septic searches run out before the budget does, related searches from sewer households take the rest. A busy trade usually has enough real searches to absorb its budget, and a thin one doesn't.
• A small campaign needs months before a zero means anything. At an illustrative one booking per ten clicks, 29 clicks is the first point where a campaign that really books one in ten would show no booking less than 5% of the time.
• The Phoenix results below cover a window in which the new map and a separate landing page went live within the same fortnight, while the account also ran Local Services Ads and a Google Business Profile. They can't be credited to either change alone, or to Search alone.

Why does a service with few competitors still waste money?

The EPA says septic systems usually serve "houses and businesses located in suburban and rural locations not served by a public (centralized) sewer system" (EPA). In a big metro that means the edges. In the Phoenix account we run, most of the addresses the plumbing campaigns reached were on municipal sewer, and the tanks were in the unincorporated county, on the acre lots, and in the areas the sewer main hasn't reached.

A company that pumps and inspects those tanks has very few competitors, because most plumbers in town have no reason to learn septic. It also has very few searches, because not many households own a tank. In the ad account the second fact matters more, because it sets how much of the budget reaches a tank owner.

What happens when the septic searches run out before the budget does?

Three documented behaviors meet in a septic campaign:

• Broad match is the default match type (broad match guide). A broad keyword matches "all the searches of equivalent phrase and exact match keywords, plus additional related searches" (keyword matching options). In Google's own example, the broad keyword purple flowers matched the search "pink flowers" (search terms report).
• Google pairs it with Smart Bidding. The matching page says Smart Bidding "works best with broad match because the wide set of searches allows it to learn".
• Maximize conversions spends the budget. It "will try to fully spend your average daily budget" (Maximize conversions).

Google doesn't say what these three do together in a thin market. What follows is our reading.

Say, purely as an illustration, a septic campaign has $60 a day, and the searches from people who own a tank inside its area can absorb about $20 of it at your market's prices. The campaign is still built to spend the other $40, and broad match gives it somewhere to go: searches related to septic, about drains, sewer lines and plumbers. In a metro mostly on sewer, those come overwhelmingly from homes without a tank. Up to two thirds of the budget reaches people who can't buy the service, and no single setting looks wrong.

The leaking share is at most roughly 1 − (what real septic searches can absorb ÷ the daily budget). In the accounts we run, air conditioning in Phoenix in July has far more real searches, so the same settings seldom need the related ones. That is why one account structure can look fine on the main trade and fail on the small one.

What the reports show and what they leave out

Search terms (Campaigns → Insights & reports → Search terms). A row marked "Broad match" in the "Match type" column is a variation of your keyword, not a search that contained it (search terms report). Google lists only terms "used by a significant number of people", and "Some search terms that don't have enough query activity are omitted" for privacy. Google adds that Search terms insights account for these omitted searches, grouped into subthemes or shown as "other queries", without showing the searches themselves. Check how much of the septic campaign sits there, then compare the cost of the listed terms with the campaign's cost. In our reading, a trade made of rare searches, like septic, has more of its spend in that gap.

Matched locations (Insights & reports → When and where your ads showed). Google says these "could be users' physical locations or locations of interest" (matched locations). The report shows where Google placed the searcher, not whether the address has a tank.

Why "Low search volume" nudges you toward broad match

The obvious fix is narrow, specific keywords, and Google has a status for those. "Low search volume" goes to a keyword "with very little to no search history on Google", which "will be inactive until its search traffic increases" (Low search volume). Google "evaluates the number of searches on a given keyword worldwide over the past twelve months", so the status says nothing about demand inside your service area.

Two of the four fixes Google lists point wider: "Change the keyword match type to something broader", or make the keyword less specific. The keyword status page says "Consider using phrase or broad match for low volume keywords". Our approach is to shorten the keyword first, keep the word septic in it, and use phrase match: "septic inspection for home sale" plus a town name becomes "septic inspection". Broad comes later, if ever, after the search terms have been read.

If you also run Performance Max, one more line on the matching page matters: a keyword with "low search volume status" is one of the reasons a search can go to Performance Max instead of your Search campaign. Google doesn't say on that page which location settings apply then. Our read is that the Performance Max campaign serves it under its own locations, so check that campaign's map too.

Draw the map around the tanks, not the metro

Google's advice is to "target the locations where you can find your customers, which isn't necessarily the same place that your business is located" (target geographic locations). For septic, the customers are where the tanks are.

Find where the sewer isn't. Start from the unincorporated county, the larger lots on the edge of the metro and the areas the sewer main hasn't reached. County records help. Maricopa County, for example, runs a free online search of its septic records (Online Septic Research). Ask your county's environmental health office what it keeps, and add the addresses of your own past septic jobs.

Enter it as zip codes you include. Google takes "up to 1000 location targets at a time" in bulk (target geographic locations). Two limits shape the list:

• Google warns that if you target "a small radius or very small location, your ads might only show intermittently or not at all" (target geographic locations), and gives no size that is safe. In our experience zip codes usually serve, and they're easy to check against county records. If a zip code shows no impressions after two weeks while its neighbors do, replace it with a radius that covers it and the zip codes next to it.
• "The number of locations you exclude shouldn't exceed the number of locations you're targeting per campaign" (excluding locations). So don't target the county and exclude forty sewer-only zip codes. Include the septic zip codes and exclude only the sewer-only pockets inside them. Where the two overlap, "exclusion takes priority".

Google may also show ads in "nearby, closely related areas that normally couldn't be targeted because of low population" (targeting geographic locations), and thinly settled land is what a septic map is made of. Check Matched locations after 30 days; the other location settings are covered in the Google Ads articles for contractors.

Don't fix it with bids. Under Maximize conversions, "your existing bid adjustments aren't used", apart from a device adjustment of −100%. A higher bid on the septic zip codes changes nothing, so the fix has to be in the map.

Decide on "Presence" with the house sale in mind. For work tied to one address we'd normally use "Presence" (why, for service areas). Septic has one search that doesn't follow the tank: the inspection before a sale, which a seller or an agent living elsewhere may arrange. We haven't measured that share. Check who booked your last inspections, and from where, before you limit the map to people physically inside it.

Give septic its own campaign and budget

In the Phoenix account, the septic keywords sat inside the plumbing campaigns, sharing their keywords, their budget and a service area drawn around the whole Valley. We spent the first month trying to make septic work inside that structure, on the theory that a small trade wouldn't support a campaign of its own, and it produced nothing.

Our reading: one budget under Maximize conversions goes where the campaign expects the most conversions, and plumbing, with far more searches, wins that contest. One ad budget for two trades shows the same effect between HVAC and plumbing. The test we use for a small service has two questions. Do its customers live somewhere different? Do they search in different words? Septic answers yes to both, so in a plumbing account it runs as a separate line, the same way drain, water-heater and repipe work get their own targets and pages. A service that shares the main trade's map and vocabulary can often stay inside it.

Keep plumbing's words out. In that account "plumber near me" was cut from the septic campaign, because inside the septic map it bought sewer-connected households (negative keywords by trade).

The search with a closing date

Arizona requires anyone selling a property served by a septic system to "retain a qualified Inspector to inspect the facility within six months prior to transferring ownership", under rule R18-9-A316, and any significant amount of waste must be pumped from each tank (Maricopa County). Other states differ, so check your own.

In the Phoenix account this was the septic search worth the most. The person searching has a closing date and books whoever answers and can come that week. That made stated availability worth more than price, and the Google Business Profile listing worth more than either. Put the soonest opening in the ads, and run them in the hours someone answers the phone.

What changed in the Phoenix account

A.P.E.S. HVAC & Plumbing sells air conditioning, heating, plumbing and septic in Phoenix. Once septic had its own campaign, its spend moved out of the central, sewer-only metro and into the unincorporated county and the acre lots.

A.P.E.S. HVAC & Plumbing · Phoenix, AZRead the case

3.2 to 3.6×

Septic inspections booked

Window

150 days against the 150 before

Source

Client CRM

A.P.E.S. HVAC & Plumbing · Phoenix, AZRead the case

−41%

Cost per booked inspection

Window

150 days against the 150 before

Source

Call tracking

How long before a quiet septic campaign tells you anything?

Take the chance that one click doesn't book, and multiply it by itself once for every click. The result is the chance of that many clicks with no booking by bad luck alone. Purely as an illustration, at one booking in ten clicks:

At one booking in twenty, the 5% point is 59 clicks. A campaign that gets eight clicks a month at one in ten needs almost four months before a zero means it is broken rather than unlucky. A campaign with dozens of clicks a day gets there within a week.

So set the review point in clicks, write it down before you look, and change one thing at a time where you can. A small campaign can't tell you which of two changes worked, and the cost figure above carries exactly that limit.

What this doesn't cover

• The housing market. Property sales drive a meaningful share of septic inspections, so part of any septic result, including the Phoenix one, belongs to the market in a way we can't subtract.
• Markets where most homes are on septic. In a rural county the tank isn't the filter, and the map argument above mostly doesn't apply.
• AI Max. Google says campaigns using the campaign-level broad match setting "will automatically be upgraded to AI Max" starting in September 2026 (broad match campaign setting). We haven't covered how AI Max behaves in a thin trade.
• Local Services Ads. This is written for Search campaigns.

Do this in your account

1. Find where septic lives. If its keywords sit in a plumbing campaign, write down that campaign's budget, map and bid strategy.
2. Read 90 days of septic search terms. Total the cost of the "Broad match" rows, then compare the cost of all listed terms with the campaign's cost.
3. Build the map from county septic records and your past septic job addresses, entered as zip codes you include.
4. Give septic its own campaign and budget, not a shared budget with plumbing.
5. Tighten the keywords. Phrase match, with the word septic in each one. Add plumbing-only searches such as "plumber near me" as negatives in the septic campaign only.
6. Shorten "Low search volume" keywords before you broaden their match type.
7. Set the review point in clicks from the table above, before you look.

FAQ

Do Google Ads work for septic companies? They can, when the campaign is built around where the septic systems are and the words people with a tank use. The waste comes from running septic inside a plumbing campaign drawn around a whole metro.

What does "Low search volume" mean in Google Ads? It is a status for keywords with "very little to no search history on Google", and they don't serve until searches rise. Google counts searches worldwide, so the status says nothing about demand in your service area. Shorten the keyword before you broaden its match type.

Should a septic campaign use broad match? In our reading, not as a starting point in a metro that is mostly on sewer. Google's own low-volume advice suggests phrase or broad match, and phrase is limited to searches that "include the meaning of your keyword". Start with phrase match and read the search terms before widening.

Can I bid more in the zip codes with septic systems? Not under Maximize conversions. Google says existing bid adjustments aren't used there, apart from a device adjustment of −100%. Change the map instead: include the septic zip codes and leave the sewer-only ones out.

Sources

All read in full on September 24, 2026. Every quotation above is from these pages.

• Google Ads Help, "About keyword matching options", https://support.google.com/google-ads/answer/7478529
• Google Ads Help, "Your guide to broad match", https://support.google.com/google-ads/answer/12159290
• Google Ads Help, "About Maximize conversions bidding", https://support.google.com/google-ads/answer/7381968
• Google Ads Help, "About the search terms report", https://support.google.com/google-ads/answer/2472708
• Google Ads Help, "View matched locations and distance reports", https://support.google.com/google-ads/answer/7492954
• Google Ads Help, "Low search volume: Definition", https://support.google.com/google-ads/answer/2616014
• Google Ads Help, "About keyword status", https://support.google.com/google-ads/answer/2453978
• Google Ads Help, "Target ads to geographic locations", https://support.google.com/google-ads/answer/1722043
• Google Ads Help, "Exclude ads from geographic locations", https://support.google.com/google-ads/answer/1722040
• Google Ads Help, "About targeting geographic locations", https://support.google.com/google-ads/answer/2453995
• Google Ads Help, "About the broad match keywords campaign setting", https://support.google.com/google-ads/answer/13389795
• US EPA, "About Septic Systems", https://www.epa.gov/septic/about-septic-systems
• Maricopa County Environmental Services, "Onsite Wastewater (Septic Systems) - Ownership Transfer", https://www.maricopa.gov/2491/Onsite-Wastewater-Ownership-Transfer
• Maricopa County Environmental Services, "Online Septic Research", https://www.maricopa.gov/2581/Online-Septic-Research