Waterfall enrichment: how it works, how to build one and what it costs

What is waterfall enrichment?

Waterfall enrichment is a method of filling one data field, usually a work email or mobile number, by asking several providers in a fixed order. If the first provider has no answer, the request falls through to the second, then the third, until one returns a result or the list runs out.

Clay's documentation describes waterfalls as a way to use multiple data providers in a predetermined sequence. The same pattern is sold as a standalone product by tools such as FullEnrich and BetterContact, and Apollo runs a version on top of its own database.

The approach exists because no single B2B data provider has every contact. Each provider sources data differently, so their gaps rarely overlap completely, and chaining them recovers rows any one of them would miss.

Most teams use waterfalls for work emails and mobile numbers, the two fields an outbound sequence cannot run without. The same logic also works for company data such as headcount or revenue when your first source returns blanks.

Why does an email waterfall raise match rates?

An email waterfall raises match rates because each extra provider only works on the rows the earlier ones failed to fill. Clay's guide to finding work emails says the best individual providers reach roughly 52 to 90% coverage depending on provider and market, and that a three-provider waterfall reaches about 90 to 95%.

Regional strength matters too. In the same Clay guide, Clay reports that BetterContact reached 90% coverage of European contacts in its tests, while Hunter had higher quality but reached only 55% of them. These are Clay's own data tests, published by a company that sells waterfalls, so treat them as directional rather than independent.

The arithmetic shows why order and overlap matter. In a hypothetical 1,000-row list, a first provider finding 60% fills 600 rows; a second finding half of the remaining 400 adds 200; a third finding 40% of the last 200 adds 80, for 880 rows or 88% in total.

How do you build a Clay waterfall for work emails?

A Clay waterfall for work emails takes a few minutes to set up from the pre-built Work Email enrichment. Clay's docs describe the steps below, and a 10-row test run before the full table catches mapping mistakes cheaply.

1. In your table, click Add enrichment and search for Work Email.
2. Choose Quick setup, or Full configuration if you need advanced Infer Email and validation settings.
3. Map the inputs: the company domain is required, plus the name fields your chosen email pattern needs.
4. Switch on the free Infer Email first step and pick an email pattern, which defaults to first.last@domain.com.
5. Set a validation provider and a validation strategy: Conservative, Balanced, Aggressive or Advanced.
6. Reorder, add or skip providers, save, and run on a small sample first.

For a waterfall from scratch, Clay's Waterfalls doc says to click Add column, choose Waterfall, set the data type, add the provider actions and save. You can save the result as a template to reuse across tables, and the same flow works for phone numbers.

How should you order providers and validate catch-all emails?

Provider order should follow your goal, not habit. Clay's guide says its default order is optimised for coverage, recommends leading with Findymail for maximum list completeness, Enrow for high-volume campaigns where partial coverage is acceptable, and BetterContact for European contacts.

Catch-all emails are the hardest part. A catch-all domain accepts mail for any address, so a guessed email can look valid and still bounce. Clay's Work Email waterfall treats catch-alls according to your strategy: Conservative includes only verified types, Balanced includes catch-alls, and Aggressive casts a wider net.

Clay's guide recommends Conservative mode for cold outbound on new sending domains and says safe-to-send-only validation cuts list size by 20 to 30% while protecting domain reputation. The docs also offer a duplicate-results threshold, suggested at 2 or higher, that stops the waterfall when the same email keeps failing validation.

How much does waterfall enrichment cost?

Waterfall enrichment cost depends on whether each provider charges per result or per attempt. Clay's Work Email docs say you only pay credits for the provider that finds a match, the Infer Email step is free, and validation costs credits but is cheaper than running the waterfall without it.

On Clay's 2026 pricing, Data Credits are the main cost. Clay's docs give 0.5 Data Credits per email found as an example, so 880 found emails would cost 880 x 0.5 = 440 Data Credits before validation, or $22 at the $0.05 starting rate. Each enrichment also uses one Action, and your own API keys remove the Data Credit cost but keep the Action.

Do not assume every tool works this way. Apollo's waterfall docs say some data sources charge only when they return data, while others may consume credits for a lookup even when they find nothing, so check each source's billing before adding it to a sequence.

Which waterfall enrichment tools work outside Clay?

Several waterfall enrichment tools sell the pattern as a packaged product, which suits teams that only need emails and phones rather than a full workflow platform. The table summarises each vendor's own pricing or docs page, checked on 17 October 2026.

You can also build a waterfall yourself in n8n or Make by calling provider APIs in sequence and stopping on the first verified result. That gives full control over order and cost, at the price of maintaining the logic yourself.

When is a waterfall not worth running?

A waterfall is not worth running when one provider already covers your market well or when the list is small enough to check manually. Each extra step adds an Action in Clay and some validation spend, so a fourth or fifth provider may recover only a handful of rows.

Pattern guessing alone is weaker than many people expect. In Clay's internal testing on a software-industry dataset, the default first.last@domain.com pattern returned a valid email roughly 31% of the time, which is why Infer Email works best as a free first step rather than a replacement.

Phone waterfalls deserve the most caution. FullEnrich and BetterContact both charge 10 credits per mobile number against 1 per work email, so run phone lookups only on rows that have already passed your qualification checks.

Waterfall enrichment: where to start

Start with one field, usually work email, and three providers. Add the free Infer Email step, set Conservative validation for new sending domains, and test on 10 to 50 rows to see which provider fills which rows.

Then reorder by what you observed, not by vendor claims, and only add providers that recover rows the others missed. Waterfall enrichment pays off when it is measured, so log match rate and cost per found email for every run. Tentt builds waterfall enrichment into outbound systems for B2B teams, and the free GTM stack resources in the Tentt newsletter include open-source tools for doing this outside Clay.