A Waterpik is at least as effective as string floss for most people, and for certain measures, particularly gum bleeding and gum inflammation, it performs meaningfully better. In one well-cited clinical trial, using a water flosser reduced bleeding by up to 93% and gum inflammation by up to 52% more than traditional floss over four weeks. That said, the full picture depends on what you’re trying to accomplish and what’s going on in your mouth.
How They Compare on Plaque Removal
Both tools remove plaque between teeth, but the numbers tilt in favor of water flossers. In a study comparing the two head-to-head, string floss reduced whole-mouth plaque by about 58%, while a water flosser reduced it by roughly 74%. The gap widened for plaque specifically between teeth: floss brought a 63% reduction, while the water flosser hit nearly 82%.
These results make sense when you consider how each tool works. String floss physically scrapes plaque off two flat surfaces of adjacent teeth. A water flosser sends a pressurized stream into the entire pocket between and around teeth, reaching curved surfaces and areas below the gumline that a piece of string can miss. It’s especially effective in the small irregular spaces where plaque tends to accumulate but where floss doesn’t make full contact.
Gum Health Is Where the Gap Widens
If your gums bleed when you floss, this is the comparison that matters most. A four-week trial at the University of Nebraska Medical Center tested 105 people split into three groups: water flosser with a manual toothbrush, water flosser with a power toothbrush, and the traditional combo of manual toothbrush plus string floss. All participants cleaned once daily with their assigned tool. By the end of the study, both water flosser groups significantly outperformed the floss group on bleeding and gingivitis scores.
The reason likely comes down to compliance and comfort. Flossing correctly requires wrapping the string in a C-shape around each tooth, sliding it below the gumline, and repeating dozens of times. Most people don’t do this thoroughly, and inflamed gums make the process painful, which leads to skipping it entirely. A water flosser requires you to point a tip at your gumline and move slowly from tooth to tooth. It’s faster, less uncomfortable on sore gums, and doesn’t punish you for imperfect technique the way floss does.
Braces, Implants, and Special Situations
Orthodontic hardware makes traditional flossing a chore. You have to thread floss under each wire, clean around each bracket, and repeat for every tooth. Studies on orthodontic patients show mixed results when comparing the two tools directly. One trial found no significant difference in plaque scores between super floss (a thicker floss designed for braces) and a water flosser. Another found that adding a water flosser to an electric toothbrush was the only combination that significantly improved oral hygiene compared to a manual toothbrush alone, and the improvement was primarily attributed to the water flosser. A third study, however, found no benefit from adding a water flosser to manual brushing in younger patients with already good oral hygiene. The takeaway: a water flosser helps most when your current routine isn’t getting the job done, which is common with braces.
For dental implants, a clinical trial tracking 76 implants across 24 patients found no statistically significant difference between floss and a water flosser on any measure, including plaque, probing depth, and bleeding. Both tools maintained implant health equally well. There was a trend toward the water flosser producing slightly greater reductions in bleeding around implants, consistent with its performance around natural teeth, but the difference wasn’t large enough to be statistically meaningful in this study. Notably, no adverse events were reported with water flosser use around implants, which addresses a common concern that the pressure might damage the tissue surrounding an implant.
Safety at Different Pressure Settings
One worry people have is whether a pressurized water stream can damage gum tissue. Research testing water flossers across a range of pressures (50 to 100 psi, which covers the full dial on most consumer models) found no negative impact on gum tissue or the attachment between gums and teeth. In fact, measurements showed stability or slight improvements in periodontal health across all pressure settings. If you’re new to water flossing, starting at a lower setting and working your way up over a few days is a reasonable approach, but you aren’t going to harm your gums by using the device at full power.
The ADA’s Position
The American Dental Association has granted its Seal of Acceptance to several Waterpik models. The ADA’s evaluation confirmed that these devices are safe and effective for removing plaque along the gumline and between teeth, and for helping prevent or reduce gingivitis. String floss also carries the ADA Seal. In other words, the ADA considers both tools legitimate options for interdental cleaning.
Which One You Should Actually Use
The best interdental cleaner is the one you’ll use consistently. That sounds like a dodge, but it’s the most honest answer. String floss, used correctly and daily, is a proven tool. The problem is that most people don’t use it correctly or daily. National surveys consistently show that a large percentage of adults rarely or never floss. A water flosser lowers the barrier: it’s faster, more comfortable, and more forgiving of imperfect technique.
If you have healthy gums, good dexterity, and an established flossing habit, there’s no urgent reason to switch. You’re already doing the work. But if you have braces, bridges, implants, crowns, periodontal pockets, or gums that bleed regularly, a water flosser gives you a practical advantage. It’s also a strong choice if you simply find string floss tedious enough that you skip it most nights.
You can also use both. Floss to physically dislodge stubborn debris wedged between tight contacts, then follow with a water flosser to flush everything out and clean below the gumline. That combination covers the strengths of each tool and leaves very little behind.