Rank #2 in Best Water Flosser 2026: 10 Ranked, and Why the Cheapest Wins
COSLUS C20 Cordless Water Flosser, 300ml, 5 Jet Tips
Price and rating as shown on Amazon when we collected them. Both change.
The COSLUS C20 is a cordless, rechargeable water flosser listed at £19.97 in black and transparent, with a stated 300 ml tank, five jet tips and a two-year manufacturer warranty. It comes second in this guide, and it is the cheapest model in it — yet it also carries the most ratings, 47,762 at 4.3 out of 5. Put that beside the £69.99 Waterpik Cordless Advanced, which has 6,194 ratings at 4.2 and does not state a tank volume at all, and the central point of this ranking is already visible: the price and the weight of buyer evidence do not move together.
The listing's own numbers are worth reading closely. The tank is given as 300 ml (10 oz); the only larger figure stated anywhere in this guide is the Waterpik Pulse's 450 ml, whose listing says it lasts 'up to 45 seconds'. COSLUS calls its 300 ml 'twice capacity of other old models' without naming those models, and promises 'high water pressure' without giving a psi figure anywhere on the page. Battery life is claimed at up to 30 days per charge, with no capacity or charging time stated, and the motor is said to last up to three years. Everything on this page comes from the Amazon listing rather than from our own testing.
How those 47,762 ratings break down
An average hides its own shape. This is the spread behind the 4.3 stars.
Specification
Exactly as published on the Amazon listing, field for field.
| Price | £19.97 |
|---|---|
| Amazon rating | 4.3 out of 5 from 47,762 ratings |
| Tank volume | 300 Millilitres (10 oz), as listed |
| Stated water pressure | No psi or pressure range given anywhere in the listing |
| Battery claim | Up to 30 days of use per full charge |
| Item weight | 442 g |
| Best Sellers Rank | 2 in Power Flossers & Irrigators |
| Warranty | 2-Year manufacturer warranty, as listed |
What buyers actually say
Quoted from customer reviews on Amazon
Verified purchase“Water capacity is enough to use twice, portability and handyness for everyone.”
Verified purchase“I recently tried the Cordless Water Dental Flosser Pick, and it has completely transformed my oral hygiene routine. With a generous 300ML tank, this portable rechargeable oral irrigator provides ample water capacity for thorough cleaning, making it perfect for both orthodontic users and those with sensitive gums.The cordless design adds a level of convenience that's hard to beat, allowing you to use it anywhere without being tethered to an outlet. It's lightweight and compact, making it an excellent choice for travel or for families who need a reliable dental care solution on the go.One of its standout features is the adjustable water pressure settings, which cater to different needs, whether you're looking for a gentle clean or a more robust jet to tackle stubborn debris. The ergonomic handle ensures a comfortable grip, making it easy to maneuver around the mouth for effective flossing.The sleek white design adds a modern touch to your bathroom countertop, while its easy-to-clean components make maintenance a breeze. Overall, the Cordless Water Dental Flosser Pick is an essential tool for anyone seeking an efficient and user-friendly way to enhance their dental care routine, ensuring healthier gums and a brighter smile!”
What it is up against
The rivals it was ranked against in Best Water Flosser 2026: 10 Ranked, and Why the Cheapest Wins.
Questions people ask
How much water does the COSLUS C20 hold?
The listing states a detachable 300 ml (10 oz) tank, described as twice the capacity of 'other old models'. It does not say which models that comparison refers to.
Does the COSLUS C20 give a water pressure figure?
No. The COSLUS listing promises 'high water pressure' and an 'ultra-fine dual-thread water pulse', but no psi number or pressure range appears anywhere in the listing.
How long does the COSLUS C20 battery last?
The listing claims up to 30 days of battery life once fully charged. It does not state the battery capacity or the charging time.
What comes in the box with the COSLUS C20?
Five replacement jet tips, the flosser itself, a user manual and a charging cable. The listing notes that an adapter is not included.
Is the COSLUS C20 waterproof?
It is listed as IPX7 waterproof and described as safe to use in the shower provided the charge port cover is fitted tightly.
How does the COSLUS C20 compare on price and ratings with the Waterpik models here?
The COSLUS C20 is £19.97 with 47,762 ratings at 4.3. The Waterpik Cordless Advanced is £69.99 with 6,194 ratings at 4.2 and lists no tank volume; the Waterpik Pulse is £35.99 with a 450 ml reservoir.
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