Frequently asked questions

Below are the answers to the most frequently asked questions about our products, grouped by topic.

How it works & Safety

ZeNO

How exactly does ZeNO work?

Is salt/resin ion exchange really the best way to remove limescale?
According to the Dutch Consumers' Association (Consumentenbond), yes: only salt-based resin ion exchange demonstrably removes limescale. Magnetic and 'no-salt' systems have not been proven to do so. That matches our own experience: after 26 years of experience in water technology, we still see salt/resin ion exchange as the only method that reliably delivers that result. ZeNO works on that proven method — no magnets, no promises, just technology that works.

Does my water become saltier after ZeNO has softened it?
Slightly. In ion exchange, the limescale (calcium and magnesium) is exchanged for sodium in the resin. That applies to every water softener that works with salt and resin, regardless of the brand and regardless of how much salt the unit uses.

The salt you put in the brine tank does not end up in your drinking water itself. The unit uses that salt to rinse the resin and make it ready for use again (regeneration); that rinse water goes down the drain. So the fact that ZeNO uses up to 60% less salt is good for your wallet and for the environment, but it does not change the amount of sodium in your water. That depends only on how much limescale is removed.

For every degree of hardness removed, around 8 mg of sodium per litre is added. If you soften from 10 to 4 °dH, for example, that is about 50 mg per litre. For comparison: the Dutch standard for sodium in drinking water is 150 mg per litre. And because you set the hardness yourself with ZeNO, you also decide how much sodium is added.

ZeNO also has a built-in bypass valve: if you open it, all the water in the house runs untreated (so also not softened). There is no separate, permanent tap that supplies only untreated water; it is all or nothing. If you follow a low-sodium diet or prepare baby formula, use the bypass specifically when you need untreated water.

Is ZeNO certified?
Yes. ZeNO is NSF/ANSI 44 certified — independently assessed, not just claimed by us.

Does ZeNO also work at low water pressure, for example in an apartment?
Yes, ZeNO also works efficiently at low water pressure.

Does ZeNO remove all the limescale from my water, or can I set that myself?
You choose: by default ZeNO removes up to 100% of limescale, or you set the water hardness you want yourself — tailored to your own use.

Is ZeNO suitable for a villa with a swimming pool, sauna or jacuzzi?
Yes. ZeNO is installed where the water enters your home and so treats every water point in the house — suitable for any home, right up to large villas. For these situations, choose the largest size (Large household/Villa).

ViruLEX

How does ViruLEX work?
Through ultrafiltration: the water passes through a membrane with pores down to 0.02 micron — fine enough to remove bacteria, viruses, moulds and microplastics up to 99.99999%.

Is ViruLEX suitable for the whole house, or only for one tap?
Both. For the whole house, ViruLEX is installed at the main water supply. At a single tap (the kitchen tap, for example) ViruLEX and SorCA come together in one filter.

Does ViruLEX also remove limescale from my water?
No — that's what ZeNO does. ViruLEX focuses on bacteria, viruses, moulds and microplastics. For soft and safe water, combine ViruLEX with ZeNO.

SorCA

How does SorCA work?
SorCA filters through a layer of activated carbon. This largely removes chlorine and any strange taste or smell, and also significantly reduces micro-pollutants: pharmaceutical and hormone residues, chemical waste from businesses and households such as PFAS, plasticisers, PAHs, pesticides and biocides, and nanoparticles.

Is the whole-house SorCA suitable for every home?
The whole-house SorCA is suitable for a household of 3 to 4 people. For a larger household, take a look at ZeNO + ViruLEX + SorCA — Large household or Villa & All-in-One.

ViruLEX & SorCA together

What is the difference between ViruLEX, SorCA, and the combination of the two?
On their own, ViruLEX tackles bacteria, viruses, moulds and microplastics; SorCA tackles chlorine, taste and PFAS. Together they also significantly reduce heavy metals, pharmaceutical residues, pesticides and radioactive/nuclear contamination: SorCA's activated carbon already absorbs most of it, and ViruLEX's ultrafiltration captures the rest — including oxidised metal particles that escape absorption.

Are ViruLEX and SorCA one unit, or two separate products?
That depends on your situation. At a single tap they are combined in 1 unit. For the whole home they are two separate products, connected to each other.

Can I get soft water with this too?
Yes — add a water softener, such as ZeNO, or use your own existing water softener. Think of the combination as insurance for your water.

Single-tap cartridges

Which cartridge suits me?
SorCA if you mainly want to tackle chlorine, taste and odour. SorCA PFAS special if you want to tackle PFAS in a more targeted way. ViruLEX & SorCA if you also want to stop bacteria and viruses. All three fit the same filter head, so you can always switch later.

What is the difference between SorCA and SorCA PFAS special?
SorCA works with activated carbon. It largely removes chlorine, taste and odour and significantly reduces micro-pollutants, including PFAS. SorCA PFAS special also has a resin column tuned specifically to PFAS. Resin and carbon both capture PFAS, so together it reduces PFAS even further.

How much does ViruLEX & SorCA hold back?
Bacteria up to 99.99–100% and viruses up to 99–99.9%. It also largely removes chlorine, taste and odour and significantly reduces PFAS and micro-pollutants.

How often do I replace the cartridge?
When the capacity in litres has been reached, and after 1 year at the latest. Whichever comes first. The capacity per size is on the product page. So a small SorCA (11,000 litres) from which you draw 20 litres a day is replaced after 1 year. A large SorCA (36,000 litres) in a family using 150 litres a day is full after about 8 months.

Want to know exactly rather than estimate? Then fit a water meter after your filter. It shows how many litres have already passed through. The digital version even warns you when it's time.

Do I have to replace the cartridge myself?
Yes, and it's done in no time. You don't need any tools and you're finished in a few minutes:

1. Water off. Close the stop valve on the cold water line and briefly open the tap to release the pressure.
2. Old cartridge out. Hold the filter head, turn the cartridge a quarter turn to the left and pull it straight down out of the head. Keep a cloth handy; a little water may run out.
3. Prepare the new cartridge. Remove the protective cap and briefly wet the rubber rings (O-rings) on top. Then it slides smoothly into the head.
4. Twist it in. Push the cartridge up into the head and turn it a quarter turn to the right until it clicks into place.
5. Water on and flush. Slowly open the stop valve, check that everything stays dry and let the tap run for 5 minutes. The first water may be a little cloudy or grey because of fine carbon. That's normal and disappears by itself.

Write the date on the cartridge, or set a reminder in your calendar. The old cartridge can go in general household waste.

Who connects the filter head?
You have the filter head connected to the cold water line once by an installer, or you do it yourself if you are very handy. Installation is not included in the price. After that the head simply stays in place and you only replace the cartridge.

Does the cartridge also work on hot water or well water?
No. Only on cold mains water (drinking water) from the water company, up to 39 °C. The water pressure must be between 0.7 and 8.6 bar. In the Netherlands, the pressure on the household water supply is usually 2 to 4 bar, so in an ordinary home you are comfortably within that range. If you have your own pump or a pressure booster with higher pressure, have a pressure regulator fitted.

Hospitality cartridge (ZeNO + SorCA for Hospitality)

Which appliances is this cartridge for?
For coffee machines, hot drinks dispensers and other hospitality equipment on a single tap. One cartridge contains two layers: first a special resin that reduces the limescale that settles when water is heated, then activated carbon that largely removes chlorine, taste and odour.

How long does the cartridge last?
That depends on the hardness of your water. The capacity on the product page applies at 10 °dH. If your water is harder, it fills up sooner. Calculate it like this: capacity × 10 ÷ your hardness. Example: the XX cartridge (7,500 litres) with water of 14 °dH can handle about 5,350 litres. If your coffee machine uses 30 litres a day, you replace it after about 6 months. In any case, replace it after 1 year at the latest. You can find your water hardness by entering your postcode on your water company's website.

Won't the water become too soft for my coffee?
No, and that's exactly the point. For good coffee you need a little hardness. When brewing an espresso, the machine forces hot water through the ground coffee in a few seconds. The minerals in the water, especially calcium and magnesium, help release the flavour and aroma compounds from the coffee. If the water is completely soft, the espresso tastes flat and sour and the crema is thin. If the water is too hard, the coffee tastes bitter and dull, and limescale settles in the boiler and pipes of your machine.

That's why a fixed, small part of the water bypasses the resin in the filter head. That water is blended back in after the resin. This leaves just enough hardness for a full flavour, while most of the limescale stays out of your machine. The activated carbon then removes chlorine and off-tastes, so your coffee and tea taste the way they're meant to.

Replacement filters for fridges

Which fridge does the replacement filter fit?
We have two replacement filters: one that replaces Whirlpool 4396508 (also Kenmore 46-9010, 46-9902 and 46-9908), and one that replaces LG LT500P (also Kenmore 46-9890 and WF290). Check the old filter or your fridge's manual to see which number you have.

What does the replacement filter do?
According to the manufacturer, it removes chlorine up to 97% (LG version up to 96%), lead up to 99% and cysts up to 99.99%. The filter is tested to NSF/ANSI 42 and 53.

How often do I replace it?
Every 6 months. That's also what Whirlpool and LG recommend themselves. For the LG filter there is also a limit of about 750 litres: if you use a lot of water from the fridge, you replace it sooner. Whichever comes first. Many fridges show a light when it's time. After replacing, reset that light according to your fridge's manual.

Water meters

What do I need a water meter for?
A water meter shows how many litres have passed through your filter. That way you know exactly when the cartridge is full, instead of estimating. Handy if you use a lot of water, or with a coffee machine where daily use varies.

What is the difference between digital and mechanical?
The digital water meter runs on a battery. You set a volume (500 to 99,500 litres) or a period (30 to 720 days), and it indicates when it's time to replace. After replacing, you reset it to zero.

The mechanical water meter works without a battery and simply keeps counting, just like the water meter in your meter cupboard. It cannot be reset. This is how you use it: when fitting a new cartridge, note the reading and add your cartridge's capacity. That number is your replacement point. Example: the meter reads 12,400 litres and your cartridge can handle 11,000 litres. When the meter reads 23,400, it's time for a new one.

Both water meters have a 3/8" connection.

Costs & Installation

The installation approach below applies to the whole product range, unless stated otherwise. Current prices are only shown on the product pages, not here in the FAQ — so a price change only needs updating in one place.

Do you also install?
No. H2Ot supplies; you install yourself or through your own installer. That applies to the whole range, including installations you order via a custom quote.

With the single-tap cartridges, you only have the filter head connected to the cold water line once, by an installer or yourself if you are very handy. That head then stays in place for good. You replace the cartridge yourself: water off, a quarter turn to the left to take it out, the new one in with a quarter turn to the right, water on and flush for 5 minutes. No tools, no installer needed.

Is installation for ViruLEX and SorCA arranged the same way as for ZeNO?
Yes — same approach: you choose who installs, yourself or your installer of choice. No indicative installation price, just like with ZeNO.

ZeNO

What does ZeNO cost?
ZeNO comes in 3 sizes — Apartment/Small household, Family/Medium household and Large household/Villa. You can find the current price per size, incl. VAT, on the product page.

What is included in the price?
One price, no small print: shipping, a 2-year warranty on the main components and the first salt fill are simply included.

Is installation included in the price?
No. You arrange installation yourself: you choose who installs ZeNO — yourself, or your installer of choice.

Can I install ZeNO myself?
ZeNO has a standard connection size (1" MNPT). If you're handy and have experience with this kind of job, you can install ZeNO yourself — but don't expect it to be like assembling an IKEA cabinet: it takes real DIY skills, such as pipework and making connections watertight. If in doubt, leave it to your own installer or plumber.

Is a water analysis needed before I order ZeNO?
Only if the water source is unknown, for example with your own well or borehole. If you are simply on the regular drinking water network, an analysis is not needed: in the Netherlands you can find the water hardness and composition of your tap water at your water company, simply by entering your postcode on their website.

Which size ZeNO do I need?
That depends on the simultaneity factor — how many taps are used at the same time. 1 to 3 people → Apartment/Small household. 4 to 6 people → Family/Medium household. Larger homes and villas (with swimming pool, sauna or jacuzzi) → Large household/Villa. In between two sizes? Then choose the larger size.

Combinations & bundles

Is installation different if I combine several products?
Not more complicated — actually simpler: with a combination you connect everything at the same point, with one installation visit and one point of contact, even though technically they remain separate, connected products.

Is ZeNO + ViruLEX + SorCA one unit?
No. At the main water supply they are three separate units placed in series: first ZeNO, then SorCA, then ViruLEX. If you only want to filter your drinking water, you can also fit SorCA and ViruLEX in one filter under the kitchen sink.

Ordering & shipping

What are the shipping costs?
Within the Netherlands, shipping is free from €100. Below that amount you pay €12.50. If you order to an address outside the Netherlands, you will see the shipping costs at checkout. For large installations we include the shipping costs in the custom quote, because they depend on size and weight.

Are prices including VAT?
Yes. All prices in the webshop include 21% VAT. For installations for businesses, the product description also shows the price excluding VAT.

How can I pay?
With iDEAL | Wero, Klarna, credit card and many other common methods. You'll see them at checkout and choose the one that suits you there.

Which countries do you deliver to?
To the Netherlands and the 26 other countries of the European Union. Live outside the EU and still want to order? Then contact us at info@h2ot.nl. We'll look at the options for delivery and shipping costs together.

When will I receive my order?
We ship your order as quickly as possible, and in any case you'll have it within 30 days. As soon as your parcel is on its way, you'll receive an email with the shipping details so you can track it. If you order an installation via a custom quote, the delivery time is stated in your quote.

I need an invoice for my business. Is that possible?
Yes. Email your order number and company details to info@h2ot.nl and we'll send you an invoice with the VAT shown separately.

Indicative price & custom quote

What does "Indicative price" on a product mean?
For larger installations, the price shown is a guide price. We tailor such an installation to your situation: the final price, delivery and shipping costs are set out in your custom quote.

How do I request a custom quote?
On the product page, click "Request your custom quote here" and fill in the form. Briefly describe your situation, how much you need and where it needs to be delivered. You'll receive your quote within 4 working days.

Am I committed to anything if I request a quote?
No. A custom quote is always without obligation. You decide yourself whether and when to order.

Can I also order an installation with an indicative price directly?
No. We put these installations together for your situation, which is why you order them via a custom quote. That way you know exactly what you're getting and what it costs beforehand.

Maintenance

ZeNO

How much maintenance does ZeNO need?
Very little. ZeNO cleans itself. You top up the salt 2 to 4 times a year, depending on the hardness of your water, and you carry out a service check once a year.

Do I ever need to replace the resin?
No — ZeNO's ion exchange resin lasts up to 10x longer than in a traditional water softener. Replacement is not needed under normal use.

How much salt does ZeNO use?
Up to 60% less than a traditional water softener, thanks to the unique tank design and the extra-fine ion exchange resin. Less topping up, less waste, less hassle.

Who carries out the annual service check?
You do it yourself, possibly together with your installer. This is how you check ZeNO:

• Check that all connections are dry.
• Clean the brine tank. If you see sediment at the bottom sooner, clean it sooner too.
• Check and clean the air vent valve.
• Check that the valve is set to Service and that the clock still shows the correct time.

Is there iron in your water (for example with your own well)? Then also run the iron cleaning mode for at least 2 weeks once a year.

Does ZeNO use a lot of water during cleaning (regeneration)?
No, ZeNO uses exceptionally little water during regeneration — one of the advantages of the calibrated resin design.

ViruLEX

How much maintenance does the whole-house ViruLEX need?
Very little. ViruLEX regularly flushes its membranes clean by itself. Once a month you carry out a cleaning: you start the cleaning programme (CIP) and add the cleaning agent within 60 seconds. You buy the cleaning agent yourself and pour it into the jerrycan inside the unit. You replace the membranes according to the manufacturer's instructions.

Does ViruLEX use a lot of electricity?
No. The power consumption is 17 watts (0.017 kW), including the backwash pump. That's about the same as two LED bulbs. The filtering itself runs on the pressure of your water supply. The pump only runs very briefly now and then to flush the membranes clean. So you'll hardly notice ViruLEX on your energy bill.

Buying with confidence

The following applies in principle to the whole product range, unless a product-specific figure is mentioned.

ZeNO

What warranty do I get on ZeNO?
A 2-year warranty on the main components, on all three models.

General (whole product range)

What happens if a product becomes faulty within the warranty period?
Got a fault or is something not working properly? Then first contact the installer who installed the product for you — they know your installation and can solve most things on the spot. If a part turns out to be broken, you or your installer can report it to H2Ot. If it falls within the warranty, we send the replacement part to you free of charge and your installer replaces it. Your installer's costs are at your own expense. If you installed the product yourself, the same applies: you receive the part and replace it yourself. If the fault is not covered by the warranty, the cost of the part will be charged to you.

Can I return a product if I'm not happy with it?
As a private customer, you have a statutory 14-day cooling-off period for online purchases (right of withdrawal).

How do I send something back?
As a consumer, you may withdraw from your order within 14 days of receipt without giving a reason. Here's how it works:

1. Let us know. Tell us within 14 days of receipt via info@h2ot.nl, with your order number. You may use the withdrawal form (annex to the terms and conditions), but a clear email is fine too.
2. Send it back. Return the product within 14 days of your notification, as far as possible in its original condition and packaging, with all accessories. We'll send you the return address.
3. Money back. You'll receive the purchase amount, including the original shipping costs, within 14 days of your notification, refunded in the same way you paid.

Good to know:

• Inspecting is fine, using is not. You may examine the product as you would in a shop. If it has been installed or used, a reduction in value may be charged.
• Return costs. The cost of sending it back is yours.
• Custom-built. An installation put together for your situation on the basis of a quote is not covered by the right of withdrawal.
• Business customers. The right of withdrawal only applies to consumers.
• Received broken or damaged? That's not a return but a report. Take a photo of the packaging and the product and email us as soon as possible. We'll sort it out.

Can I return a cartridge or filter?
Yes, as long as the seal is still intact. Filters, cartridges and membranes arrive in sealed packaging. That seal is your guarantee that the filter is clean and unused: nobody has touched it and no water has passed through it yet.

Once the seal is broken, we can no longer verify that the filter has stayed clean. A filter is in direct contact with your drinking water, so for hygiene reasons we cannot resell such a product or take it back. This is also how the law treats sealed products. Not sure which cartridge you need? Feel free to ask us before you open the packaging.

Where can I find the user guide?
Your order confirmation, shipping email and packing slip contain a QR code. Scan it with your phone and you'll get to all the user guides. Then find the one for your product and you'll have all the information, including what your installer may need. Can't find it? Email info@h2ot.nl.

Why choose H2Ot instead of a bigger, better-known brand?
H2Ot builds on 26 years of experience in water technology, supplies water treatment systems and filters from European production and handles support and parts from the Netherlands. ZeNO works on the same proven technology as well-known leading brands — without the hype and test-winner claims of the rest of the market.

Is H2Ot a reliable, registered company?
Yes. H2OT Water Solutions is registered in the Netherlands (Chamber of Commerce 76125971, VAT number NL860516520B01), based in Alphen (North Brabant).

MembraSAL, LiquSON & MixO3

MembraSAL has fixed prices in the webshop. For the larger installations you'll see an indicative price and request a no-obligation custom quote. LiquSON and MixO3 are coming to the webshop soon; until then we assess them case by case — get in touch for a no-obligation quote.

MembraSAL — Desalination (RO)

What is MembraSAL?
A reverse osmosis (RO) system that removes salts and minerals from brackish or salt water — the right choice for coastal homes or brackish well water.

Can I drink the water that comes out?
Not directly: the water coming straight out of the system is too pure to drink as it is. A separate element adds the minerals back, so the same installation still supplies water of drinking-water quality.

What is MembraSAL mainly used for?
Mainly for applications where the water isn't necessarily drunk, such as hospitality or cleaning. For stricter applications (such as hospitals or dental practices), what is needed is assessed per situation.

Is the first set of membranes and cartridges included with the installation?
Yes. Every MembraSAL installation includes the first membranes and cartridges. You only replace them over time; you'll find the individual parts in the Parts & accessories collection.

Which replacement membrane belongs to my installation?

Installation	Replacement membrane	Quantity
MembraSAL Desalination 150 l/h	Replacement membrane — MembraSAL 150 and 300 l/h	1
MembraSAL Desalination 300 l/h	Replacement membrane — MembraSAL 150 and 300 l/h	2
MembraSAL Desalination 250 l/h	Replacement membrane — MembraSAL 500 l/h, Large household, Villa and Complete station	1
MembraSAL Desalination 500 l/h	Replacement membrane — MembraSAL 500 l/h, Large household, Villa and Complete station	2
MembraSAL — Complete station 1,000 l/h	Replacement membrane — MembraSAL 500 l/h, Large household, Villa and Complete station	4
MembraSAL — Large household	Replacement membrane — MembraSAL 500 l/h, Large household, Villa and Complete station	2
MembraSAL — Villa & All-in-One	Replacement membrane — MembraSAL 500 l/h, Large household, Villa and Complete station	2
MembraSAL for Coffee 100 l/h	Replacement membrane — MembraSAL for Coffee 100 l/h	1
MembraSAL for Coffee 120 l/h	Replacement membrane — MembraSAL for Coffee 120 l/h	2
MembraSAL Off-grid 120 l/h	Replacement membrane — MembraSAL Off-grid 120 l/h	2

How often should I replace membranes and cartridges?
As a guideline: replace the membrane every year for MembraSAL for Coffee and roughly every 2 years for the home installations. Replace the cartridges (carbon block, nanofiltration, mineralisation and pre-filter) according to the manufacturer's instructions; the interval per part is shown on the product page. If your water is heavily contaminated or you use a lot of water, it may be needed more often.

LiquSON — Ultrasonic antifouling

What is LiquSON?
A system that uses a continuous, inaudible sound wave to prevent fouling (algae, mussels, biofilm) on surfaces that are permanently underwater — a ship's hull, for example.

Who is LiquSON for?
For boat owners, from sloop to yacht.

Does LiquSON need maintenance?
No — install and switch it on once, after which the system keeps running in the background.