Cirkul’s Personalization Strategy, From Bottle to Inbox

Personalization has come a long way from simple subject line swaps and product recommendations. Today, brands face a new challenge: turning mountains of customer data into meaningful, respectful, real-time experiences. In this new landscape, successful brands aren’t the ones shouting the loudest—they’re the ones listening the closest.

Meet Cirkul: A Brand Built on Personalization

At Cirkul, we’re reimagining the way people hydrate. Our innovative water bottles and flavor cartridges let customers personalize every Sip—choosing from over 130 flavors and multiple intensity levels to craft a drinking experience that fits their lifestyle and their tastebuds!. Whether it’s an energy boost, electrolytes, or simply pure refreshment, Cirkul makes it easy to drink more water, precisely the way our customers like it.

As a direct-to-consumer brand with a growing presence, delivering a personalized customer experience isn’t just a nice-to-have—it’s essential. With such a customizable product, our customers expect the same level of flexibility and relevance in their communications. That’s where Iterable comes in. 

Personalization’s Shifting Sands: From “Big Brother” to “Brand That Gets Me”

When I hopped on to talk with the Iterable team about this post, we went down a rabbit hole about personalization—how it started, how it’s going, and what customers expect now.

Just a few years ago, I remember having conversations with colleagues that sounded something like: “Is this too creepy?” “Are we crossing the line into Big Brother territory?” We wanted to deliver personalized experiences, but were hyper-aware of being too overt with how we used a customer’s data.

Fast forward to today, and the landscape has drastically changed.

Modern consumers not only know we have their data—they expect us to use it—and not just in a generic, “Hi [First Name]” kind of way. They want thoughtful messaging, timely nudges, and an experience that reflects their preferences. We live in a world where everyone assumes you have some level of data. If you’re not using their data to improve their experience, you’re falling short of their expectations and delivering a poorer outcome.

Not utilizing that data to enhance their experience results in a disjointed and frustrating customer journey.

This is where moments-based marketing comes in. It’s not about blasting the same message to everyone—it’s about reaching the right person, at the right time, with the right message. In a world flooded with content and choices, relevance is the new currency. 

Respectful Personalization: Where Relevance Meets Trust

Personalization has incredible power, but when it crosses into overreach, it stops feeling helpful and starts feeling invasive.

We’ve all seen the cautionary tales: brands referencing details a customer never explicitly shared, or tapping into third-party data in ways that feel more like surveillance than service. Once you misuse data like that, the brand doesn’t just lose a sale—it loses trust.

Instead, think of personalization as a way to respect your customers. Use what you know to improve their experience: help them reorder before they run out, suggest new products based on what they’ve loved, or tailor their onboarding to reflect where they are in the journey.

Here’s what I’ve found works:

• Transparency builds trust, and zero-party data is a key part of that. When you invite customers to share their preferences or rate what they’ve tried, you collect valuable insights directly from the source. This empowers the customer and enables you to deliver relevant, personalized experiences—without crossing any lines.
• Personalization should feel like a helpful nudge, not a hard sell. It’s not about shouting “Buy now!” at every turn. It’s about surfacing products they’ll love at the right time, based on their behavior or preferences. Maybe it’s a reminder to restock a favorite, or a suggestion based on past orders. When done right, it feels like the brand “gets you”—not like it’s watching you.

Good personalization is just good communication, which keeps customers coming back. 

How Cirkul Uses Data to Enhance the Customer Experience

At Cirkul, personalization isn’t just a marketing tactic—it’s baked into the product itself.

From the moment a customer picks their first flavor, they’re crafting an experience that’s uniquely theirs. With over 130 flavors and the ability to control intensity with every sip, Cirkul turns hydration into a form of self-expression. That level of customization sets the tone for everything we do, from product to messaging.

• Closing the Feedback Loop with Flavor Ratings. We encourage customers to rate their flavors, helping us collect data directly from the source. This feedback loop not only improves our offerings—it powers more thoughtful, relevant recommendations. 
• Letting Favorites Shape the Future. Without flavor ratings, we take cues from order history to infer preferences and personalize accordingly. We might recommend new flavors that complement what someone already enjoys, highlight energy-boosting options for those who favor caffeinated blends, or surface electrolyte options for wellness-minded customers.
• Tailoring Onboarding Based on Customer Context. Our welcome emails reflect what we already know, like whether the customer purchased a bottle with their first order—so we can tailor the experience to their level of familiarity. Newer customers might get tips on using their bottle, while returning customers can discover new flavors or subscription benefits quicker.
• Perfect Timing with Send Time Optimization. One behind-the-scenes strategy we love is Iterable’s Send Time Optimization. This AI-powered feature automatically sends emails when each customer is most likely to engage. It’s a small detail that makes a big impact—ensuring our messages appear when our customers are ready to listen.

Personalization isn’t just about product suggestions—it’s about communication that feels like it was made for you. Every email, every offer, and every ask is rooted in the same principle: relevance builds trust, and trust builds loyalty.

Personalization That Puts the Customer First

At Cirkul, we know what’s possible when personalization is rooted in respect, relevance, and real-time insight. It’s not about using more data—it’s about using it better. Whether it’s flavor suggestions or onboarding flows, personalization isn’t a tactic for us—it’s a relationship builder. And when it’s done right, customers feel understood, not targeted.