Waterdrop K19 Review UK: I Tested TDS, Noise, Flow & Taste

The Waterdrop K19 is one of the easiest ways I’ve found to get reverse osmosis water without installing anything under your sink. But after actually using and testing it at home, there are a couple of compromises you should know about – particularly dispensing speed and the taste compared with a remineralised RO system.

I’ve tested several systems while researching my best reverse osmosis systems in the UK, and our main kitchen system is a plumbed-in Waterdrop G5P700A with alkaline remineralisation. You can also read my full Waterdrop G5P700A review.

If you’re still deciding which filtration system is right for your home, read our complete Water Filters UK guide comparing reverse osmosis systems, under-sink filters, countertop filters and whole-house filtration.

So rather than simply repeating the K19 specifications, I put it through some basic real-world tests.

I measured:

• TDS of the filtered water
• Noise while operating
• Time required to dispense 250 ml
• Approximate flow rate
• Taste
• Ease of setup and everyday use

I also performed the same tests against my G5P700A where possible.

My overall verdict: the Waterdrop K19 is a very convenient countertop RO system if you don’t want plumbing or can’t install an under-sink system. Filtration performance was impressive in my testing and it was surprisingly quiet. However, water dispensing is considerably slower than my plumbed-in RO system, and I personally prefer the taste of remineralised RO water.

Disclosure: Waterdrop supplied this unit for me to review. They have not been allowed to influence my findings or the results below. This article contains affiliate links, which means I may receive a commission if you purchase through them, at no additional cost to you.

Waterdrop K19 Review: Quick Verdict

What I liked

✓ Genuine reverse osmosis filtration
My filtered-water TDS measurement was only 31 ppm.

✓ No plumbing required
Fill the reservoir, plug the machine in and let it flush. There’s no drilling through a worktop or altering your plumbing.

✓ Much quieter than I expected
I measured approximately 47 dB average and 51 dB maximum during my test.

✓ Hot filtered water on demand
This makes the K19 particularly useful if you regularly make tea or coffee.

✓ UV treatment
The system incorporates UV as part of its treatment process.

✓ Useful built-in display
You can see information including TDS and filter status directly on the machine.

What I didn’t like

✗ Dispensing is relatively slow
It took 23.62 seconds to dispense 250 ml in my test.

✗ RO water tastes quite neutral
The water tasted very clean, but I preferred the slightly crisper taste from my remineralised G5P700A.

✗ You have to refill the tank
That’s inevitable with a countertop RO system, but it’s something a permanently plumbed system avoids.

✗ Takes up worktop space
It’s compact for what it does, but substantially larger than a filter jug.

My rating: 4.3/5

Best for: renters, offices, flats, people who don’t want plumbing work, or anyone wanting RO filtration plus instant hot water in one countertop appliance.

I’d choose an under-sink RO system instead if: you own your home, have suitable plumbing and want considerably faster water delivery with nothing sitting on the worktop.

Waterdrop K19 Instant Hot Water Reverse Osmosis System

The Waterdrop K19 is an installation-free countertop reverse osmosis water dispenser with instant hot water, a 5L feed tank, smart TDS display and 6-stage filtration. I tested its TDS, noise, dispensing speed and taste at home and compared it directly with my Waterdrop G5P700A.

Product Brand: Waterdrop

Editor's Rating:
4.3

Pros

• No plumbing or permanent installation required
• 31 ppm TDS in my real-world test
• Quiet operation in my testing
• Instant filtered hot water up to 95°C
• 5L feed water tank
• Simple filter replacement
• Smart TDS and filter-life display

Cons

• Much slower dispensing than my Waterdrop G5P700A
• Water tasted slightly flatter than my remineralised G5P700A
• Feed water tank needs manual refilling
• Takes up kitchen or desk worktop space
• No alkaline remineralisation on the standard K19-H

What Is the Waterdrop K19?

The Waterdrop K19-H combines a countertop water dispenser with a reverse osmosis filtration system.

Unlike a conventional under-sink RO system, it doesn’t need connecting permanently to your cold-water pipe or waste.

You fill the 5-litre feed-water tank, connect the machine to electricity and it processes the water internally.

The K19 is a point-of-use drinking-water system rather than a whole-house filter. If you’re unsure which approach you need, I’ve explained the differences in my whole house water filter vs reverse osmosis comparison.

Waterdrop currently specifies the K19-H as a 75 GPD, six-stage filtration system using a 0.0001 μm RO membrane together with UV treatment. The company lists a 3:1 pure-to-drain ratio and dimensions of approximately 35 × 20 × 41.5 cm, with a weight of 7.3 kg.

Waterdrop says its filtration reduces substances including TDS, nitrate, fluoride, arsenic, lead, copper, chlorine and chromium-VI, among others. Those are manufacturer/third-party laboratory claims rather than contaminants I independently laboratory-tested for this review.

That’s an important distinction.

My testing below measures TDS, flow, sound and my subjective experience – it isn’t a laboratory contaminant-removal test.

Why I Wanted to Test a Countertop RO System

Our kitchen already has a permanently installed RO system.

The big advantage of that installation is convenience. Turn on the dedicated tap and filtered water comes out.

But look underneath the sink.

There is equipment, tubing, a water connection and a waste connection occupying cupboard space.

The K19 removes virtually all of that installation work.

That’s potentially a big deal if you:

• rent your home;
• live in a flat;
• don’t want to drill your worktop;
• don’t have suitable under-sink space;
• want RO water in an office or study; or
• simply want something you can take with you when you move.

If you’re happy to have a permanent installation, I’ve also compared the best under-sink reverse osmosis systems in the UK, which are generally a better fit if fast, on-demand filtered water is your priority.

Setting Up the Waterdrop K19

Setup is one of the K19’s strongest features.

There’s no plumber required.

I positioned the machine on the worktop near a socket, filled the reservoir and allowed the machine to complete its initial flushing process.

You will hear the internal pump operating during filtration/flushing. That’s normal.

I initially saw an L1 warning on the display. Waterdrop’s own FAQ says that when L1 appears the feed tank should be lifted and refilled.

Once it was correctly filled and the initial flushing completed, the system was straightforward to use.

This is a fundamentally different experience from installing an under-sink RO system.

That picture tells the story better than I can.

My Waterdrop K19 TDS Test

This was the first objective test I wanted to perform.

I measured:

Waterdrop K19: 31 ppm

For comparison, water from my installed Waterdrop G5P700A measured:

G5P700A: 22 ppm

Is 31 ppm good?

For an RO system, 31 ppm demonstrates that the machine was producing low-TDS water in my test.

But there’s an important caveat.

TDS measures dissolved ions electrically. It doesn’t tell you individually how much lead, PFAS, pesticide or another specific contaminant is present. PFAS is a good example of why TDS alone cannot tell you exactly which contaminants have been removed. I’ve looked separately at the evidence and treatment options in my guide to the best water filters for PFAS in the UK.

So don’t interpret a 31 ppm reading as proof that every contaminant has been removed.

For that you’d need appropriate laboratory testing.

What it does give us is a simple, repeatable indication that the RO process was substantially reducing dissolved material in the water.

Waterdrop K19 Noise Test

This produced one of the more interesting results.

Countertop RO systems contain a pump, so they’re not completely silent while producing water.

I measured the K19 and my G5 using the same phone and at the same distance.

My results

The K19 was noticeably quieter in this test.

Using the same phone at the same distance, I recorded a 47 dB average from the K19 compared with 62 dB from my G5.

I wouldn’t treat a phone sound-meter app as laboratory-grade instrumentation, so the absolute numbers shouldn’t be over-interpreted.

However, because I tested both machines using the same device, same app and same distance, the relative difference is useful.

This was a pleasant surprise.

If you’re considering keeping the K19 in a study or office, noise isn’t something that would particularly concern me.

How Fast Does the Waterdrop K19 Dispense Water?

This is where I found the K19’s biggest weakness.

Rather than describing it as “fast” or “slow”, I timed it.

I measured how long each system took to dispense approximately 250 ml.

Results

My G5 was therefore approximately 4.6× faster in this particular dispensing test.

That’s a very substantial difference.

At those measured rates, filling a 500 ml bottle would theoretically take roughly:

K19: ~47 seconds

G5: ~10 seconds

That’s one of the main differences between a compact countertop RO appliance and my plumbed-in high-flow system.

It isn’t necessarily a deal-breaker.

For filling a mug or glass, waiting 20-odd seconds isn’t terrible.

But if you’re regularly filling several large bottles, you’ll notice it.

What Does Water From the Waterdrop K19 Taste Like?

This is obviously subjective, but I tasted the two waters back-to-back.

My impression was:

K19: very clean and neutral, but slightly flat.

G5P700A: noticeably crisper.

I preferred the G5.

There’s a logical reason why remineralisation could contribute to that difference.

RO membranes remove a large proportion of dissolved minerals along with unwanted dissolved substances. Very low-mineral water can therefore taste neutral or “flat” to some people.

My G5 setup includes alkaline remineralisation, which introduces minerals after RO treatment.

The standard K19-H doesn’t have alkaline remineralisation. Waterdrop’s newer K19-HG does; Waterdrop lists mineralisation as one of the differences between the two models.

However, I can’t prove that remineralisation alone caused the taste difference. The two machines have different filtration systems, and taste is subjective.

So my conclusion is simply:

Both tasted clean, but I personally preferred the crisper taste from my remineralised G5.

Hot Water Is One of the K19’s Biggest Advantages

This is where comparing the two purely on flow rate becomes slightly unfair.

The K19 isn’t simply trying to replace a filtered-water tap.

It’s also effectively replacing a kettle.

Waterdrop specifies adjustable heating up to 95°C / 203°F, with its instant-heating system designed to provide hot filtered water without maintaining an entire tank of boiling water.

That means you can use RO-filtered water directly for things such as:

• tea;
• coffee;
• herbal drinks;
• hot water for cooking; and
• other drinks requiring controlled hot water.

For someone who drinks several hot drinks each day, this considerably improves the K19’s appeal.

How Much Space Does the K19 Need?

Waterdrop gives the dimensions as approximately:

35 cm deep × 20 cm wide × 41.5 cm high.

The 20 cm width is particularly helpful.

It’s relatively narrow, although you’ll need sufficient depth and height for the machine and access to its reservoir.

Someone with a smaller kitchen may prefer an under-sink system precisely because it leaves the worktop clear.

K19 vs Under-Sink Reverse Osmosis: Which Is Better?

Having both types of system makes the distinction quite clear to me.

I wouldn’t say one design is universally better.

They’re solving different problems.

If I were renting a flat tomorrow and couldn’t modify the plumbing, I’d happily use the K19.

If I owned the property, had the cupboard space and wanted maximum convenience for a family, I’d still choose a good plumbed-in RO system.

What About Waste Water?

Reverse osmosis produces a concentrate/reject stream as part of the filtration process.

Waterdrop specifies a 3:1 pure-to-drain ratio for the K19-H.

That’s an important consideration with any RO system because not all of the water entering the filtration process becomes drinking water.

The difference here is that there’s no permanent drain connection.

That’s good for installation, but it means interacting with the reservoir is part of owning the machine.

It’s the price you pay for making an RO system genuinely portable.

Filter Replacement and Running Costs

Waterdrop currently specifies its K19RF composite replacement filter for approximately 12 months of use. Actual filter life will inevitably depend on usage and incoming water conditions.

The display provides a filter-life reminder, so you aren’t expected to remember the replacement date yourself.

The pull-out filter arrangement also makes replacement much simpler than servicing many traditional multi-cartridge RO installations.

I would still price the replacement filter before buying the machine.

The purchase price is only one part of the cost of owning any water-filtration system.

Is the Waterdrop K19 Certified?

This is an area worth checking carefully rather than relying on vague claims about “tested filtration”.

Waterdrop currently lists the K19-H with NSF/ANSI 42, 58 and 372 certification on its UK product specifications.

NSF/ANSI 58 is particularly relevant because it relates specifically to reverse-osmosis drinking-water treatment systems.

As always, certification applies to the specific performance claims and configuration covered by the certification rather than meaning that a product removes every conceivable contaminant.

Who Should Buy the Waterdrop K19?

I think the K19 makes the most sense for someone who wants genuine RO filtration but doesn’t want a conventional RO installation.

It’s particularly attractive for renters.

You’re not modifying someone else’s kitchen, and if you move home, the water filter moves with you.

I’d also consider it for:

An office or study:
It’s relatively quiet and only needs water and electricity.

A flat:
Particularly where under-sink space is limited.

People who can’t drill their worktop:
No additional drinking-water tap is required.

Hot-drink users:
RO filtration and instant heating are combined in one appliance.

People unsure about committing to a permanent RO installation:
It’s an easy way to use RO without modifying your plumbing.

Who Shouldn’t Buy It?

I’d think twice about the K19 if your priority is maximum flow rate.

My 250 ml test made that very obvious.

Likewise, a large family filling multiple bottles throughout the day may eventually find refilling the feed-water reservoir annoying.

And if you already have the space and freedom to install an under-sink RO system, I’d seriously compare the two approaches before buying.

Waterdrop K19 vs K19-HG

There’s now another wrinkle for UK buyers.

Waterdrop also sells the K19-HG.

The standard K19-H reviewed here uses six-stage filtration without alkaline mineralisation.

The K19-HG uses seven-stage filtration and adds minerals after RO filtration. Waterdrop also specifies five metric dispensing volumes of 150, 250, 350, 500 and 750 ml on the HG.

Given that I preferred the taste of my remineralised G5 water, the HG is the version I would investigate if taste is particularly important to you.

I haven’t personally tested the HG, however, so I’m not going to claim it tastes better without doing so.

My Verdict: Is the Waterdrop K19 Worth Buying?

After testing it properly, I think the Waterdrop K19 is a good countertop RO system – provided you understand what you’re gaining and what you’re giving up.

Its biggest strength isn’t that it beats a good under-sink RO system.

It’s that it gives you RO filtration without needing one.

There’s no drilling, no permanent plumbing connection and no equipment occupying your under-sink cupboard.

In my testing, filtered water measured 31 ppm TDS, while the machine averaged around 47 dB in my sound test.

Those were impressive results.

Its biggest weakness was dispensing speed.

250 ml took 23.62 seconds, compared with only 5.18 seconds from my G5P700A.

I also preferred the taste from my remineralised G5, although taste is subjective.

Final score: 4.3/5

Filtration performance: ★★★★★
Ease of installation: ★★★★★
Noise: ★★★★½
Taste: ★★★★
Dispensing speed: ★★★
Convenience: ★★★★½

I recommend the K19 if:

You want RO water but don’t want or can’t have an under-sink installation.

I’d choose an under-sink RO instead if:

You own the property, have suitable space and prioritise fast, unlimited-feeling access to filtered water over portability.

Waterdrop K19 FAQs