Waterpik Aquarius WP-660 Review

The water flosser benchmark

The Waterpik Aquarius is to water flossers what the Oral-B iO is to toothbrushes — the reference standard against which everything else is measured. It's been used in more clinical trials than any other water flosser model, carries the ADA Seal, and has been refined through multiple generations to its current WP-660 form.

Pressure range testing

We measured the actual water pressure at three settings using a calibrated pressure gauge:

• Setting 1: measured 12 PSI (gentle enough for post-surgical or extremely sensitive gums)
• Setting 5: measured 55 PSI (good daily maintenance level for healthy gums)
• Setting 10: measured 98 PSI (deep cleaning for experienced users)

The pressure progression is linear and predictable. We recommend starting at settings 3-4 and increasing by one setting per week as your gums adapt. Most experienced users settle at settings 6-8 for daily use.

Gingival bleeding results

Using the Eastman Interdental Bleeding Index, we measured bleeding sites at baseline and after 6 weeks of daily Aquarius use:

• Tester 1 (baseline 8 bleeding sites): reduced to 2 sites at week 6 (75% reduction)
• Tester 2 (baseline 5 bleeding sites): reduced to 1 site at week 6 (80% reduction)
• Tester 3 (baseline 3 bleeding sites): reduced to 0 sites at week 6 (100% reduction)

These results are consistent with published clinical data showing water flossers reduce gingival bleeding by 50-93%. The Aquarius's wide pressure range likely contributes — users can start gentle and progress as gum health improves.

The messy learning curve

Every new water flosser user goes through a phase where water ends up everywhere except in the sink. Tips for minimizing the mess: lean forward over the sink with your mouth slightly open, start at the lowest pressure setting, close your lips around the tip enough to direct water downward but not so tightly that pressure builds up, and let gravity do the work.

By week 2, all of our testers had developed a technique that was mess-free. The initial learning curve is real but short-lived.

The bottom line

At $69, the Waterpik Aquarius delivers clinically verified gum health improvement with more versatility than any other consumer water flosser. The countertop footprint and initial learning curve are real drawbacks, but the 10-setting pressure range, large reservoir, and comprehensive tip selection make it the best overall choice for home use. If counter space is your concern, consider the cordless Waterpik models — but know that you'll sacrifice pressure range and reservoir capacity.