If you only run one data provider, you are seeing roughly half your TAM. Even the best single source — Apollo, Lusha, ZoomInfo — finds a verified mobile for one buyer in three. The other two move on without your call. That is the gap waterfall enrichment closes.
What a waterfall actually does
A waterfall is a routing rule, not a vendor. For each contact you submit — name + company + LinkedIn — Pronto queries providers in priority order, takes the first verified result, and stops. If the top provider misses, the request rolls down to the next one. And the next. Until either a verified contact is returned or the chain is exhausted.
Three things make this work in practice: provider scoring, response normalization, and validation at the edge.
- Provider scoring — each provider has a known hit rate by region, role, and seniority. The order is not fixed; it is computed per request.
- Normalization — phones come back as +33 6 12, 06 12, or +33612. The waterfall flattens all of that to E.164 before validation.
- Validation at the edge — every email is HLR-checked, every phone pinged. Bounces never reach your CRM.
If your CRM has 10,000 contacts and you trust the data, a single-source enrichment leaves 6,500 of them unreachable.
The math everyone skips
Run the numbers on your own pipeline. If your enrichment rate is 55% on Apollo and 40% on Lusha, a naive overlap gives you 55% + 40% × (1 - 55%) = 73%. Stack 8 providers with imperfect overlap and you cross 92%. That is not theoretical — it is what we measure in production every week.
+30%additional contacts unlocked when waterfall replaces a single-provider stack
When the waterfall hurts you
It is not free. Each step of the chain costs a credit. Three pitfalls to avoid:
- Charging credits on partial data (only a name, no domain). Always validate the input before the chain starts.
- Over-stacking providers with the same source feed. Lusha and ContactOut share data with each other — adding both rarely lifts the rate.
- Skipping the credit-back rule on bounces. Your finance team will notice within one quarter.
Build it yourself or buy
You can absolutely build a waterfall in Clay. Plenty of teams do — and it works for a single, small list. The pain shows up at scale: re-running the same waterfall every Monday across a 50,000-contact CRM, with provider keys rotating, with credit caps to respect, with rate limits to back off from. That is where Pronto picks up.
Want to test waterfall on your own list? Run a 100-contact sample on our free tools page. No signup. No credit card. Just numbers.
