# Ayus > Ayus installs and maintains 4-stage water filters at home, hidden under the kitchen sink. Water with no chlorine taste, with added magnesium. Fonte de vida. Mains water in Portugal meets the legal standards. What we do is make it nicer to drink, and tell you exactly what the filter does and what it does not do. - Full text (guides, news and main pages): https://ayus.pt/en/llms-full.txt - English: https://ayus.pt/en/ ## Key facts ### What is Ayus? Ayus installs and maintains 4-stage water filters at home, hidden under the kitchen sink. Water with no chlorine taste, with added magnesium. ### How does the filter work? Mains water enters the filter, flows through four cartridges and comes out of your 3-way tap. No electricity, no tank and no water thrown away. Sediment (Holds back sand, rust and dirt.); Activated carbon (Removes the taste and smell of chlorine.); Ultrafiltration (Holds back microplastics, bacteria and fine particles.); Magnesium (Adds magnesium to the water.). ### Where does Ayus install? Lisbon, available right away, and other districts by appointment. ### How do I book a visit? Book a free visit: https://ayus.pt/en/book-a-visit/ · WhatsApp +351 910 843 263 ### How much does it cost? [PRICE TO BE CONFIRMED]. Prices are not published on the site yet; the visit is free. ## How a 4-stage home water filter works 01. **Sediment**: Holds back sand, rust and dirt. This is the first barrier. The cartridge fibres trap the particles the water picks up along the way, especially in the pipes of older buildings. It protects the next stages and makes them last longer. 02. **Activated carbon**: Removes the taste and smell of chlorine. Chlorine is added to water so it reaches your home safely. Once it has done that job, the activated carbon traps it in its pores, together with the organic compounds that cause bad taste and odour. 03. **Ultrafiltration**: Holds back microplastics, bacteria and fine particles. The water flows through the walls of hollow fibres with [X] µm pores. Anything larger stays outside. A microplastic measures at least 1 µm. The dissolved minerals in the water pass through. 04. **Magnesium**: Adds magnesium to the water. In the last stage, the water flows over magnesium granules, which dissolve little by little. That is what gives Ayus water a rounder taste. ## Why Ayus: filter, installation, testing and follow-up - **The filter**: Four stages in order: sediment, activated carbon, ultrafiltration and magnesium. No electricity and no wasted water. - **The installation**: Done by us, in about [X] hour, with no building work and no dust. The 3-way tap uses the hole of your current one. - **The test**: We measure the chlorine and minerals in your water before and after installation, in front of you. Plus a blind taste test. - **The follow-up**: We know when each cartridge reaches the end of its life. We let you know, book the visit and change it. There is always someone on the other end on WhatsApp. - **The monthly update**: Every month you get a summary of the water in your municipality and the state of your filter: what the water utility has published and when your next change is due. - **The warranty**: A [N]-year warranty on the equipment and 30 days to change your mind, because the sale takes place in your home. ## What it does - Removes the taste and smell of chlorine. - Reduces the organic compounds that cause bad taste and odour. - Holds back sand, rust and dirt from the pipes. - Holds back microplastics: the membrane pores measure [X] µm, and a microplastic is at least 1 µm. - Holds back bacteria and other microorganisms. - Keeps the minerals and adds magnesium. - Puts an end to bottles and jugs at home. ## What it does not do - It does not cure or prevent disease. - It does not change your body’s pH. - It does not remove limescale. - It does not need to scare you to convince you. ## Pages - [Ayus · Home water filters, installed and maintained](https://ayus.pt/en/): Ayus installs and maintains 4-stage water filters at home, hidden under the kitchen sink. Water with no chlorine taste, with added magnesium. - [How a 4-stage home water filter works](https://ayus.pt/en/how-it-works/): Sediment, activated carbon, ultrafiltration and magnesium: what each stage of the Ayus filter does to your tap water, with no electricity and no waste. - [3-way tap: hot, cold and filtered water](https://ayus.pt/en/3-way-tap/): The Ayus 3-way tap gives hot, cold and filtered water, fits in the same hole as your current tap and comes in brushed steel, matte black and brushed brass. - [What the water filter does and doesn’t do](https://ayus.pt/en/what-it-does-and-doesnt/): The Ayus filter removes chlorine taste, holds back sediment, microplastics and bacteria over [X] µm and adds magnesium. It does not remove limescale. - [Why Ayus: filter, installation, testing and follow-up](https://ayus.pt/en/why-ayus/): Not just a water filter: Ayus installs it, tests your water, changes the filters, sends you monthly updates on your water and gives a [N]-year warranty. - [Maintenance and filter changes](https://ayus.pt/en/maintenance/): When the filters are changed, who changes them and what is included in the maintenance of Ayus water filters. We remind you and book the change for you. - [Tap water by municipality in Portugal](https://ayus.pt/en/water/): Where your municipality’s tap water comes from, who manages it and its published magnesium, calcium and hardness values. Map of all 308 municipalities. - [Your body and water: how much you have, how much to drink](https://ayus.pt/en/water-and-your-body/): About 60% of an adult’s body is water and EFSA recommends 2 to 2.5 L of water a day, including water from food. The facts, with sources. - [Bottled water calculator: money, bottles and plastic](https://ayus.pt/en/bottled-water-calculator/): Work out how much you spend on bottled water, how many bottles you buy and how many kilos of plastic you throw away each month and year. - [Guides to tap water at home](https://ayus.pt/en/guides/): Clear guides to tap water in Portugal: chlorine taste, bottled water, reverse osmosis and ultrafiltration, microplastics. No scaremongering. - [News from Ayus and about water in Portugal](https://ayus.pt/en/news/): Ayus news, press and stories about tap water in Portugal. Ayus installs and maintains 4-stage water filters at home. - [Home water filter FAQ](https://ayus.pt/en/faq/): Straight answers about Ayus water filters: tap water safety, limescale, reverse osmosis, microplastics, electricity, warranty and filter changes. - [About Ayus: water filters installed and maintained at home](https://ayus.pt/en/about/): Who Ayus is, what it does and why it has that name. 4-stage water filters, installed and maintained at home, in Portugal. - [Water filters for business: offices, restaurants and hotels](https://ayus.pt/en/business/): Ayus installs and maintains 4-stage water filters in offices, restaurants and hotels. Free site visit and water test, maintenance included. - [Contact us: WhatsApp, email and address](https://ayus.pt/en/contact/): Talk to Ayus on WhatsApp, by phone or with the form. Available right away in Lisbon; in other districts, by appointment. - [Book a visit](https://ayus.pt/en/book-a-visit/): Book an Ayus visit: we test the water in your kitchen, free and with no commitment, and show you the difference the 4-stage filter makes. ## Guides to tap water at home - [Why does my tap water taste of chlorine?](https://ayus.pt/en/guides/chlorine-taste-in-tap-water/) (2026-10-20): Tap water tastes of chlorine because water utilities add a small dose of chlorine so it reaches your home safely. It is normal and within the law. To get rid of the taste, you can let the water stand in a jug or use an activated carbon filter, which traps the chlorine. - [Tap or bottled water: which to choose in Portugal?](https://ayus.pt/en/guides/tap-or-bottled-water/) (2026-10-20): In Portugal, tap water is within the law and checked every year, so you can drink it. A household of two adults that only drinks bottled water spends about €390 a year and throws away nearly 867 bottles of 1.5 L. If taste is what keeps you away from the tap, a filter solves that with no bottles. - [Reverse osmosis, ultrafiltration or a filter jug?](https://ayus.pt/en/guides/reverse-osmosis-or-ultrafiltration/) (2026-10-20): Reverse osmosis removes almost everything from the water, minerals included, and sends part of the water down the drain. Ultrafiltration holds back particles such as microplastics and bacteria but lets dissolved minerals through, with no waste. A filter jug mainly reduces the chlorine taste. - [Microplastics in water: what a filter can hold back](https://ayus.pt/en/guides/microplastics-in-water/) (2026-10-20): A microplastic is a plastic particle smaller than 5 mm, and the ones looked for in water are at least 1 µm. An ultrafiltration membrane with pores of [X] µm keeps out anything larger than its pores. It is a question of size, and that is what we explain here. - [How much water should you drink a day?](https://ayus.pt/en/guides/how-much-water-to-drink-a-day/) (2026-10-20): About 60% of an adult’s body is water. EFSA sets an adequate intake of 2.0 L of water a day for women and 2.5 L for men, including the water in food. About 70 to 80% of that water comes from drinks. ## News - [Ayus has a new website, in five languages](https://ayus.pt/en/news/ayus-has-a-new-website/) (2026-10-20): Our new website is in Portuguese, English, French, German and Spanish, for everyone who lives in Portugal and speaks another language at home. - [Free visit: we test your water at home](https://ayus.pt/en/news/free-visit-we-test-your-water/) (2026-10-16): We come to your home free and with no commitment: we test the chlorine and minerals in your water in front of you and show you the difference the 4-stage filter makes. - [Client area: filter changes, water and invoices](https://ayus.pt/en/news/client-area-replacements-summary-and-invoices/) (2026-10-13): We are preparing the Ayus client area. If you are already a client, get in touch and we will activate your access. - [The 3-way tap, now in three finishes](https://ayus.pt/en/news/3-way-tap-in-three-finishes/) (2026-10-08): The 3-way tap, which gives hot, cold and filtered water, now comes in brushed steel, matte black and brushed brass. - [How the monthly water summary works](https://ayus.pt/en/news/how-the-monthly-water-summary-works/) (2026-10-02): Every month we send you information about the water in your municipality and your filter, so you know what you drink and when the next change is due. - [Calculator: how much bottled water costs](https://ayus.pt/en/news/calculator-how-much-bottled-water-costs/) (2026-09-29): We have added a calculator to the site: choose the people, the bottles and the price, and see the money, bottles and plastic in a month, a year and five years. - [Ayus for business](https://ayus.pt/en/news/ayus-for-business/) (2026-09-24): The same 4-stage filter and the same service, adapted to offices, restaurants, hotels and other places where people work. - [Filter changes, without you having to remember](https://ayus.pt/en/news/how-we-change-your-filters/) (2026-09-19): We know when your filters reach the end of their life, let you know on WhatsApp and book the visit. You do not need to keep track. - [New guides: chlorine, microplastics, daily water](https://ayus.pt/en/news/new-guides-chlorine-microplastics-and-how-much-water-to-drink/) (2026-09-15): We have added three clear guides to the site, without alarmism and with sources: chlorine taste, microplastics and how much water to drink a day. ## Tap water by municipality - [Tap water by municipality in Portugal](https://ayus.pt/en/water/): Where your municipality’s tap water comes from, who manages it and its published magnesium, calcium and hardness values. Map of all 308 municipalities. - [Cascais](https://ayus.pt/en/water/cascais/): Lisboa, Águas de Cascais. - [Lisboa](https://ayus.pt/en/water/lisboa/): Lisboa, EPAL. - [Oeiras](https://ayus.pt/en/water/oeiras/): Lisboa, SIMAS de Oeiras e Amadora. - [Amadora](https://ayus.pt/en/water/amadora/): Lisboa, SIMAS de Oeiras e Amadora. ## Home water filter FAQ ### Isn't tap water safe? It is. Mains water in Portugal meets every legal parameter. The filter improves the taste and adds magnesium; it's not a safety issue. ### Does the filter remove limescale? No. It keeps the minerals and adds magnesium. If you live in a hard water area, we'll tell you before booking the visit. ### Is it reverse osmosis? No. Reverse osmosis removes almost all the minerals from the water. Our filter uses ultrafiltration, which lets the minerals through. ### Does the filter hold back microplastics? Yes. The pores of the ultrafiltration membrane measure [X] µm, and anything larger doesn't get through. A microplastic is at least 1 µm. ### Does it need electricity? No. It runs on mains water pressure alone, with no pump and no tank. ### Do you install all over the country? In Lisbon we can come right away. In other districts, we install by appointment: leave us your details and we will arrange a date. ### What's the warranty? The equipment has the 3-year legal warranty. And since the sale happens in your home, you have 30 days to change your mind. ### How often are the filters replaced? [INTERVALO A CONFIRMAR]. We'll message you on WhatsApp when it's time and book the replacement. ### Do I need to change my tap? Yes, to a 3-way tap, which we fit in the same hole as your current one. It gives you hot, cold and filtered water, and you choose the finish. ### Where does the filter go and how much space does it take? It sits out of sight under the kitchen sink. It takes up [MEDIDAS A CONFIRMAR]. ### How long does the installation take? About [X] hour, with no dust. By the time we leave, you've got filtered water at the tap. ### Do I need any building work? No. The 3-way tap uses the hole of your current tap and the filter sits under the sink. We install in flats and in houses. ### Does the filter waste water? No. Unlike reverse osmosis, it doesn't send water down the drain. And it doesn't need a tank: the water is filtered the moment you turn on the tap. ### Does the filter change how the water tastes? Yes. It removes the chlorine taste and smell, and the magnesium gives the water a rounder taste. ### Can I use filtered water for cooking, coffee, tea and ice? You can. Without the chlorine taste, your coffee, tea, ice and food taste better. ### Is filtered water suitable for babies? Mains water in Portugal meets the legal standards. For preparing baby formula, follow your paediatrician's advice. The filter improves the taste of the water and doesn't replace medical advice. ### Does the visit cost anything? No. The visit and the test of your water are free, with no commitment. ### Can I install it in a rented home? [A CONFIRMAR]. The 3-way tap uses your current tap's hole, so there's no building work and no new holes. ## Contact - Phone and WhatsApp: +351 910 843 263 - Email: hello@ayus.pt - Address: R. Marques de Oliveira 6, 2745-165 Queluz, Portugal ([Map](https://www.google.com/maps/search/?api=1&query=R.%20Marques%20de%20Oliveira%206%2C%202745-165%20Queluz%2C%20Portugal)) - Installation areas: Lisbon, available right away, and other districts by appointment - Book a free visit: https://ayus.pt/en/book-a-visit/ ## This summary in other languages - [Português](https://ayus.pt/llms.txt) (pt-PT) - [Français](https://ayus.pt/fr/llms.txt) (fr) - [Deutsch](https://ayus.pt/de/llms.txt) (de) - [Español](https://ayus.pt/es/llms.txt) (es) ## Optional - [Privacy Policy (Portuguese)](https://ayus.pt/privacidade/) - [Terms and Conditions (Portuguese)](https://ayus.pt/termos/)