Installing a water filter: step-by-step plan

Reading time: ~13 minutes

Most people don't put off getting a water filter because they doubt its usefulness, but because they're afraid of the installation. Drilling into the countertop, hiring a plumber, a leaking cabinet: it sounds like half a Saturday's work. In practice, with a modern inline filter it turns out to be far easier.

This guide walks through the installation step by step for the standard situation in a Dutch kitchen, plus the four different connections you may come across in practice, the Quooker combination, the rental situation and the safety rules nobody talks about. If you're still looking for the right model, start with our comparison of the best water filter under the counter.

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1. What does installing a water filter mean?

There are three ways to bring filtration into your home, and they differ enormously in installation work:

• Inline under-counter (no drilling): the filter is placed between the angle stop valve and the existing mixer tap. No extra hole, no extra tap, water from the tap that's already there. This is the installation that takes 5 to 10 minutes.
• Under-counter with a separate filter tap: you drill an extra hole, usually 12 to 13 mm, into the countertop for its own little tap. Allow 1 to 2 hours, and a countertop where drilling is safe to do.
• Without installation: a filter jug or a tap filter attached to the faucet. Zero installation time, but you have to refill it, you lose flow, and the filter capacity is a fraction of an inline system.

This guide focuses on the first two, with an emphasis on inline, because that's the scenario where most people can manage without a professional. If you're still unsure about the type, our page on choosing a water filter will help you on your way.

2. Can you install a water filter yourself?

Yes, in by far most kitchens you can. The reason is simple: you don't touch any fixed pipework. Under your sink are two angle stop valves (cold and hot) with flexible hoses running from them to your mixer tap. An inline filter is fitted in between using union couplings. You don't cut anything, you don't solder anything, and you don't need any press tools.

You do need a professional in three cases: if your angle stop valve no longer closes properly or leaks, if there's no separate shut-off valve and you'd have to use the home's main stopcock, or if you want a filter with its own tap in a granite, ceramic or composite countertop. Drilling into those materials requires a diamond bit, cooling and a steady hand, and a botched hole can't be repaired.

3. What do you need and what should you check beforehand?

The checklist under your sink

Kneel down in front of the cabinet for a moment and run through these five points. It takes two minutes and prevents most surprises.

• Space: an inline filter cartridge is usually around 30 to 35 cm tall. Measure the free height next to the trap, standing or lying down.
• Angle stop valve: is there a separate shut-off valve on the cold water line, and does it turn off smoothly? A seized valve is the only real stumbling block.
• Connection size: in the Netherlands the angle stop valve is almost always 3/8 inch male thread, with a flexible hose with an M10 union nut to the mixer tap. Note down what you see.
• Water pressure: Dutch drinking water companies supply water at ample pressure. PWN, for example, maintains a minimum of 2 bar. That's enough for a carbon inline filter; only reverse osmosis systems may need a booster pump at low pressure.
• Bucket and cloth: there's always about half a litre of water left standing in the hose. Put something underneath to catch it.

Tools

For an inline installation: nothing, or at most a pair of water pump pliers to loosen a tightly fastened union nut. With the PureFilter Mineral+, the hoses, couplings and mounting bracket are included in the box. For a version with a separate tap, you will need a hole saw, a screwdriver and PTFE tape.

4. Installing a water filter in 7 steps

This is the standard procedure for an inline under-counter filter on the cold water line. Read through all seven steps before you start.

Step 1: Shut off the cold water supply

Turn the angle stop valve on the cold water line clockwise to close it. Then briefly open the kitchen tap on cold until nothing more comes out. This way you're sure the right valve is closed and you relieve the pressure from the line.

Step 2: Disconnect the flexible hose

Place a bucket under the angle stop valve. Loosen the union nut of the cold water hose, turning it counterclockwise. Hand strength is usually enough; otherwise, give it one turn with pliers. Let the remaining water drain into the bucket.

Step 3: Put the filter in place

Decide where the cartridge will sit: upright against the side wall is most convenient, because you can then simply unscrew it again when replacing it. Keep at least 5 cm clear underneath the cartridge, so you can disconnect it later without dismantling everything. Attach the bracket if one is included.

Step 4: Connect the inlet to the angle stop valve

Screw the supplied hose from the filter inlet onto the angle stop valve. Pay attention to the flow direction: almost every filter housing has an arrow or the markings IN and OUT. Connecting it the wrong way round shortens the lifespan and worsens the filtration. Tighten it hand-tight plus a quarter turn; the rubber seal does the work, not the force.

Step 5: Connect the outlet to your tap

Connect the filter outlet to the flexible hose that runs to your mixer tap. Make sure the hoses form wide bends and don't kink or sit under tension anywhere; a kink is the most common cause of disappointing flow.

Step 6: Open the valve slowly

Open the angle stop valve half a turn, not all the way at once. Look and feel along both couplings. If it stays dry, open it further. If you see a drop, close it again and tighten the relevant union nut a little further.

Step 7: Flush the filter

Let the cold tap run for 5 to 10 minutes. The water may look slightly grey or cloudy at first: that's fine carbon dust from the new cartridge and it's harmless. Keep flushing until the water is clear and tastes neutral. This isn't an optional step, but the step that determines whether your first glass tastes good.

5. If your tap connection is different: four situations

Not every kitchen is standard. These are the four variations we see most often in practice, along with the solution.

Situation 1: no angle stop valve

In older homes, the separate shut-off valve is sometimes missing and the hose is connected directly to the pipe. In that case you have to close the home's main stopcock to work. If so, have an angle stop valve fitted right away; that's a ten-minute job for an installer, and you'll benefit from it every time you do a repair in the kitchen afterwards.

Situation 2: different thread size

If you come across 1/2 inch instead of 3/8 inch, you solve that with a reducing nipple from the hardware store for a few euros. Wrap PTFE tape clockwise around the thread, three to four layers, and only then tighten it.

Situation 3: too little space in the cabinet

If the trap is in the way or the cabinet is shallow, you can mount the cartridge lying down or against the back wall, or place the filter in the adjacent cabinet with a longer hose. The important thing is just that you can reach the cartridge without dismantling the whole setup, because you replace it once a year.

Situation 4: designer tap with a fixed supply

Some designer taps have fixed, non-detachable supply lines with their own coupling piece. That's not a problem for an inline filter: you simply place the filter before that coupling piece, directly behind the angle stop valve. The tap itself is left untouched.

6. Installing a water filter with a Quooker

This is the question we get asked most often, and it isn't answered on any of the existing installation pages. A boiling water tap heats water, but doesn't purify it: PFAS, microplastics and heavy metals pass straight through unhindered. Filtering and boiling are therefore two separate functions.

The connection is simple. The filter goes on the cold water supply before the tank, so between the angle stop valve and the feed to the Quooker tank. This way both your cold tap water and the boiling water get filtered, and the tap's operation remains unchanged. Never place the filter after the tank or on the hot water line: filter media are designed for cold water. You can read more about this combination on our page about the water filter for the Quooker.

Worried about the warranty on your boiling water tap? You're not changing the appliance itself, you're placing something ahead of the supply. If you want certainty, just check with your supplier before you start. And keep in mind that filtered water that you then boil is still filtered water: on the question of whether it's better to drink cold or warm tap water, we wrote a separate blog.

7. Installing in a rental home or apartment

An inline filter is ideally suited for renting, for one reason: it's completely reversible. You don't drill, you don't change anything about the fixed installation, and when you move you screw the original hose back onto the angle stop valve in five minutes. No trace is left behind.

If you do want a version with its own filter tap, you need the landlord's permission, because an extra hole in the countertop is a permanent change. Ask for that in writing and keep the email. A more detailed explanation per living situation is in our guide on a water filter in a rental home.

In apartments there's one more thing to consider: with a shared water supply, the pressure on higher floors may be slightly lower. For a carbon inline filter this is rarely a problem, but if you notice a clearly weaker flow after installation, check the little screen in your tap first. According to Vitens, a clogged aerator screen is one of the most common causes of low water pressure, and you can fix that with vinegar.

8. Rules and safety: backflow prevention and water pressure

Anyone connecting an appliance to the drinking water installation in the Netherlands has to deal with NEN 1006 and the associated water supply guidelines (waterwerkbladen). According to waterwerkblad 3.8, the connection of an appliance must be fitted with backflow prevention that matches the risk level of that appliance, and safeguards must remain accessible for maintenance and inspection.

For a closed drinking water filter, that risk is low: the water is under mains pressure, nothing is added that could flow back into the network, and there's no open connection. Even so, there are three practical rules you follow regardless:

• Cold water only: filter media and housings are not made for hot water lines.
• Use only materials suitable for drinking water: check the certification of hoses and housing. The NSF/ANSI 61 standard specifically covers the material safety of components that come into contact with drinking water; NSF/ANSI 42 covers taste and aesthetics, and NSF/ANSI 53 covers substances with a health effect.
• Keep it accessible: a filter you can only reach with a screwdriver and a torch won't get replaced on time.

If you're unsure about your specific situation, for example in a commercial building or a shared installation, have the connection carried out by a certified installer.

9. Installing it yourself or having it done: the comparison

The practical conclusion: the less that changes in your kitchen, the greater the chance that the filter will still be in place in three years' time and replaced on schedule. If you want to see how different systems compare on filter performance, our page on the best water filter can help, and for the technology under the hood, see the explanation of how a water filter works.

10. After installation: flushing, checking for leaks and replacing

The 24-hour check

Place a sheet of kitchen paper or a dry cloth under the couplings and check it the next day. A leak that only shows up after hours is almost always a union nut that wasn't quite tightened enough, or a seal that's sitting crooked. In that case, close the valve, disconnect, check the rubber ring and reassemble. Never use brute force: a cracked union nut leaks worse than a loose one.

When do you replace the filter?

A PureFilter Mineral+ filter cartridge lasts up to 12 months, regardless of whether it "still looks fine". Filter capacity is a finite thing: NSF International even requires manufacturers to state that capacity, precisely because a saturated filter no longer holds on to substances. You replace it the same way as installing it: close the valve, take out the cartridge, put in a new one, flush. Allow five minutes.

You don't clean an inline filter

This misunderstanding comes up often. A sealed inline cartridge isn't a little strainer you rinse out: the medium has become saturated with what it has captured. Flushing doesn't restore that capacity and can encourage bacterial growth. Replacing it is the only correct route.

11. Buying advice

If installation is your biggest hurdle, choose deliberately based on ease of installation and not just on filter performance. Three criteria carry the most weight.

• No drill hole: an inline system that works with your existing tap rules out all risk of damage to the countertop and works just as well in a rental as in an owned home.
• Independently certified: look for NSF 42, 53, 61 and 372. That's the difference between "improves the taste" and "demonstrably removes substances with a health effect".
• One replacement moment per year: the more often you have to do something, the greater the chance it gets forgotten.

The PureFilter Mineral+ scores on all three: inline, NSF-certified on 42, 53, 61 and 372, and one cartridge per year at €65.00, less than one cent per litre. You can weigh that against bottled water, which according to Milieu Centraal has a climate impact per glass comparable to about 70 glasses of tap water, and is also many times more expensive.

Why filter if the tap water is already fine? That's true too: according to Vewin, Dutch drinking water meets the statutory standards in almost all measurements. The issue lies in what the standard doesn't cover. The RIVM has applied a guideline value for PFAS in drinking water of 4.4 nanograms per litre since October 2022, and notes that drinking water from river water exceeds that limit in more than half of the measurements. In addition, some of the contamination doesn't come from the supply chain but from your own pipes. A filter at the point of use is exactly the place where you catch that. Feel free to compare the full range of water filters for the home before deciding, or go straight to the page where you can buy a water filter.

12. Frequently asked questions

13. Conclusion

Installing a water filter in the standard Dutch kitchen isn't a chore but a quick action: close the angle stop valve, disconnect the hose, fit the filter in between, open the valve, flush. The five minutes it takes are shorter than the time most people spend putting it off.

The choice that matters most is made before installation: do you choose a system that requires drilling, or an inline filter that works with your existing tap? If you choose the latter, the barrier stays low, the filter stays accessible, and in a year's time you'll replace it just as easily as you fit it today. And then you're filtering at the point of use, exactly where the water goes into your glass.

Replace the filter periodically with the original replacement filters for lastingly pure water.