COSLUS E40 Water Flosser Review: Is 10-Level Pressure Control Worth It?
When I first started using the COSLUS E40 Water Flosser, I set the pressure dial to 4 and left it there. A few weeks later, 4 started to feel too weak, so I clicked the dial up — 5, then 6. I'm at level 7 now, and I haven't touched it in a while.
The E40 is a cordless water flosser with a 10-level pressure dial, a 300mL tank and five tips in the box. It sells for $39.99. I've been using it every night, mostly in the shower. This is what that's been like.
Pressure levels: 10 (30–150 PSI) | Modes: Floss, Massage | Tank: 300mL | Tips: 5 included | Waterproof: IPX7 | Battery: 1400mAh, about 4 hours to charge | Noise: <72dB | Charging: USB, wall adapter not included | ADA Accepted
Best for:
- People new to water flossing who want to start at a low pressure and work their way up
- Anyone who keeps adjusting a setting until it feels right
- Two people sharing one device who prefer different pressures
Skip if:
- You want the smallest, lightest flosser for travel
- You set one pressure and never change it
- Low, medium and high presets are all you'll ever want
I started at level 4 and now use level 7
The first few sessions, I stayed at level 4 just getting used to the water stream. Then the problem showed up: at level 4, the pressure was too light to flush food debris out from between my teeth. It didn't get them clean.
So I clicked the dial up, one stop at a time — 5, then 6, then 7. That's where I've stayed.
4, 5, 6, 7 are separate stops on this dial. On a three-setting flosser, going from medium to high is one big step. Here it's one click, and I made that move three times over a few weeks without ever feeling like the jump was too much.
A full tank lasts me about 90 seconds at level 7
With the 300mL tank filled and the pressure at level 7, I get about 90 seconds. That's my whole routine, start to finish, without stopping to refill.
That's my number, not a spec. How long a tank lasts depends on your pressure setting, how continuously you keep the water running, and your technique.
The trade-off is size. Full, the E40 is a fairly chunky thing to hold. It's not a tiny travel flosser, and I wouldn't pack it as one. For me, finishing without a refill stop is worth the size. If packing small matters more to you, a compact travel model will make more sense.
I mostly stay in Floss mode
The E40 has Floss and Massage modes. Day to day I use Floss. I've tried Massage a few times; I don't reach for it.
Once I found a pressure I liked, the pulse pattern stopped mattering to me. Massage might suit someone else — it doesn't do anything for me.
I use it in the shower at night
Most nights I use the E40 while showering. Water flossers splash, and in the shower I don't have to care. The IPX7 waterproof rating is what makes that possible.
It's a small thing, but it's the reason the habit stuck. The flosser lives where I already am at night.
My gums bled more when I first started
When I first started, I noticed some gum bleeding. It happens much less often now.
I won't claim the E40 itself fixed that. Bleeding can be tied to plaque-related inflammation, pressure, technique, or other gum problems — and my routine also got more consistent over the same period. What changed on my end: I started at a lower pressure, got comfortable with the technique, and worked up to level 7 slowly.
If your gums bleed when you start water flossing, don't respond by cranking the pressure up. If the bleeding is persistent or getting worse, that's a conversation for a dentist, not something to solve by experimenting with stronger settings. Our guide to why gums may bleed when water flossing covers the possible reasons in more detail.
The standard jet tip does almost all the work
Five tips come in the box. On a normal day I use one: the Standard Jet Tip, moving along the gumline and pausing between neighboring teeth.
The other three — Orthodontic, Periodontal, Tongue Cleaner — are for specific jobs. I don't use them day to day.
I clean the reservoir about once a week
About once a week I take the reservoir off and rinse it with warm water. The tank detaches from the handle, which makes rinsing the inside much easier than cleaning it in place.
No very hot water, no descaling products — warm water does the job. How often you need to do this depends on how often you use the flosser and how you store it, but once a week works for me.
So, is the 10-level dial worth it? For me, yes. I started at 4 because that was all I wanted, found it too weak to clear the debris between my teeth, and got to 7 one click at a time. If you set one pressure and never touch it again, the ten levels won't do anything for you. If you're the type who keeps adjusting until it feels right, you'll use them.
A big tank that gets me through a session, one tip I use and three I mostly don't, a rinse with warm water once a week. That's my E40.
Before You Go…
Here are a few handpicked articles to inspire your next self-care moment.
