FAQ

We believe filtration claims should be supported by evidence.

Every Claii filter uses a Doulton® Ultra Sterasylceramic candle, made in England since 1826. Below are the independent laboratory reports for that element, including its NSF certification.

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DOWNLOAD TEST REPORTS

Doulton Ultra Sterasyl PFAS Reduction

Doulton Ultra Sterasyl Pharmaceutical Reduction

Doulton Ultra Sterasyl Heavy Metals Reduction

Doulton Ultra Sterasyl Chemical Reduction

Doulton Ultra Sterasyl Pesticides Reduction

Doulton Ultra Sterasyl NSF Certificate

How long does it take to filter water?

It takes about 1 to 2 liters per hour to filter water.

What is the filter element made off?

The combination of a microfilter ceramic outer, granular activated carbon and heavy metal removal media effectively reduces a range of different contaminants, including bacteria, trace organics, enhanced organics, pharmaceuticals, PFAS and heavy metals such as lead

Does the filter remove beneficial minerals?

Improves water quality and taste, while preserving natural minerals, like calcium, magnesium, and potassium.

How does it preserve the natural minerals?

Beneficial minerals such as calcium, magnesium and potassium exist in water as tiny dissolved, electrically charged particles called ions. 

They are much smaller than contaminants like bacteria, microplastics and sediment, so they pass straight through the ceramic’s microscopic pores, keeping the natural minerals your body needs.

Do I need to remineralise the water?

Because our water filters maintain essential minerals, there is no need to remineralise the water.

However, should you still like to add mineral stones or drops to your water this is perfectly fine and will not affect the efficacy of the filtration process.

Do your filters alkalise the water?

Our ceramic water filters are designed to effectively remove impurities, improve taste, and provide clean, fresh drinking water. However, they do not specifically alkalise water or significantly alter its pH level.

If you want to increase your water’s alkalinity, you may want to consider additional alkalising solutions, such as mineral cartridges or natural methods like adding alkaline minerals.

How does the ceramic water filter work?

This water filter works with a simple gravity-fed drip system. Water is poured into the upper chamber and slowly filtered through a ceramic filter element into the lower chamber.

How does the filter element work?

Our ceramic filter element uses a four-stage filtration process to reduce a wide range of unwanted contaminants while helping preserve the natural minerals found in water.

Stage 1: Ceramic microfiltration

The outer ceramic layer captures bacteria, cysts, sediment, and other fine particles through sub-micron filtration.

Stage 2: Antibacterial protection

Silver ions embedded within the ceramic help inhibit the growth of microorganisms on the filter itself, supporting cleaner and longer-lasting performance.

Stage 3: Activated carbon filtration

A core of granular activated carbon reduces chlorine and a variety of organic compounds, helping improve the taste and smell of your drinking water.

Stage 4: Heavy metal & PFAS reduction

A specialised filtration medium helps reduce contaminants such as lead and PFAS from your water.

• Filters particles down to 0.5 microns
• Up to approximately 1500 litres filtration capacity per candle
• Gravity-fed filtration (no electricity required)
• Compatible with claii water filters
• Long-lasting ceramic filtration technology

How much water does it hold?

12 litres, 6 litre in the top chamber and 6 litre in the lower chamber.

How long does it take to filter water?

It takes about 1 to 2 liters per hour to filter water.

How do I care for my filter?

The flow of water may slow over time — this is a natural result of the filter doing its work.

To restore flow, remove the filter and gently clean the surface with a clean, soft brush under cool water. Do not use soap or detergent. The filter does not need to be reset after cleaning.

Check the filter regularly for build-up to ensure consistent performance.

Avoid exposure to temperatures below 4°C, as this may damage the filter.

What is the capacity of the filter candle?

Doulton Ultra Sterasyl: 1500 litres.

When should I replace my filter candle?

Replacement timing will depend on the quality of the local water conditions and frequency of use. Under average conditions and if cleaned regularly, your filter will provide filtration for an average of 6 months depending on the usage. After this stage, the activated carbon becomes too saturated and will no longer function optimally.

Are there other filter candles compatible with Claii water filters ?

There are many other filter candles that are compatible with our vessels. Feel free to contact us about this matter.

Is each ceramic filter unique?

Yes. Each Claii ceramic water filter is individually handcrafted, which means no two pieces are exactly alike. Subtle variations in shape, texture, and glaze are a natural part of the ceramic-making process and reflect the character of handmade craftsmanship. These small differences are what make each filter truly one of a kind.

What if a part of the ceramic vessel breaks?

Should an accident happen, we offer replacement parts so you don't need to replace the entire filter system. If you need a replacement part, please contact us at info@claiistudio.com

Is the ceramic food-safe?

Yes. All claii ceramic vessels are made using food-safe materials and glazes suitable for contact with drinking water. Every component that comes into contact with water is carefully selected to meet safety standards, so you can enjoy filtered water with confidence.

Where is the ceramic filter made?

Each water filter is handcrafted in Portugal in a small, family-run factory, that has been passed down through five generations.

Claii is here to celebrate traditional craftsmanship and natural materials. We believe everyday objects should be both beautiful and functional, bringing a sense of calm and intention to your daily rituals.

As our production grows, we remain committed to working with trusted ceramic makers who share our values of quality, craftsmanship, and thoughtful design.

Tap water

Yes. Claii is designed primarily for filtering tap water. It reduces a wide range of unwanted contaminants including chlorine, bacteria, microplastics, PFAS, heavy metals and many organic contaminants, while preserving naturally occurring minerals.

Rain water

Yes, Claii can be used with collected rainwater, provided the rainwater is of reasonably good quality and collected and stored hygienically. Rainwater should be kept in a clean, covered storage system and should not be left stagnant under conditions that encourage bacterial growth. If the quality or storage conditions are uncertain, we recommend having the water tested before using it for drinking.

Bottled water

Yes. Bottled water can be filtered through Claii. This can be particularly useful for reducing microplastics and other unwanted contaminants that may be present in bottled water. However, one of Claii’s main purposes is to help reduce our reliance on single-use plastic bottles altogether.

Stream & natural spring water

Claii can filter good-quality natural water and significantly reduce bacteria, cysts, sediment and various other contaminants. However, untreated surface water can be affected by wildlife, agriculture, rainfall or contamination upstream. We therefore recommend testing the source before relying on Claii for drinking water.

Sea water

No. Claii does not desalinate water and cannot turn seawater into drinking water.

Swimming pool water

No. Claii is not designed to make swimming pool water suitable for drinking.

Not sure about your water source? Send us your latest water analysis and we'll be happy to help you understand whether Claii is suitable for your water.

Water Leaking

99% of the time leaking from the vessel is a sign that your tap needs to be tightened. You will need to empty the vessel and holding the nut on the inside tighten the tap by at least one full turn clockwise until it is watertight.

If there is water dripping from the spout of the tap within 72 hours of delivery, please us via email at info@claiistudio.com to arrange for a replacement part to be sent to you.

Abnormal taste

Often described as fishy, chalky or chemically, the funny taste sometimes experienced with a brand-new filter candle is a result of the initial degasification process of the media inside the ceramic filter candle. After being flushed properly, this taste will dissipate. This process is usually quite quick but can take up to a few days.

How much are shipping costs?

We offer free shipping on all orders over €50, to countries across Europe* & United Kingdom. You can find the full list of eligible countries on our Shipping Policy page.

* For Switzerland and Norway, a flat rate of €30 applies, whatever the order value.

Please refer to our Shipping Policy for further details.

Do you ship internationally?

For now, we only ship to selected countries within Europe. If you are located outside Europe don't hestitate to contact us at info@claiistudio.com to see what the shipping options/costs are.

If you have any questions about shipping to your country, please feel free to contact us before placing your order.

How long does shipping take?

Once your order has been dispatched, estimated shipping times are typically:

• Europe + UK: 3–10 business days
  

You will receive a tracking number as soon as your order ships.

What if my ceramic filter arrives damaged?

We take great care in packaging every order, but in the rare event that your filter arrives damaged, please contact us within 48 hours of delivery and include photos of the damage and packaging.

We will work with you to find the best solution as quickly as possible, whether that means sending a replacement part or replacing the damaged item. Your satisfaction is important to us, and we want you to enjoy your claii filter for years to come.

Can I modify or cancel my order?

Please contact info@claiistudio.com as soon as possible if you wish to modify your order. Depending on whether your order has been dispatched, we are happy to modify any orders that have not yet been processed.

Take thirty days

Water tastes different after a week. A ceramic filter looks different in your own kitchen than in a photograph. So take a month with it.

You have 30 days from the day your order is delivered to decide whether to keep it. If it is not right for you, email us at info@claiistudio.com within those 30 days and we will take care of the rest.