Water filter companies in Barcelona: what to ask before you sign
Before you hire a reverse osmosis or water purifier company in Barcelona, ask every company the same questions. Here is the checklist we would use, with Oasly's own answers alongside so you can compare.
Two ways to have drinking water at home. Left: a dispenser with bottles. Right: an Oasly reverse osmosis unit under the sink.
What to check before signing with a water filter company
These questions work for any reverse osmosis or purifier company, whether you rent or buy. The right-hand column shows our answers.
Published price or quote
Is the price on the website, or only after a visit? Ask for the yearly total in writing
Published: €24.90 every 4 weeks or €249/year in Barcelona city; €27.90 or €279/year in Badalona, L'Hospitalet, Sant Cugat and Esplugues
What's included
Installation, filters, the yearly filter change, technician call-outs: what the fee covers and what costs extra
Installation, filters, maintenance and the yearly filter change are included in the subscription
Contract length and notice
Minimum term, early-exit penalty and notice period
No minimum term; two months' written notice
Who owns the unit
Is it rented or yours? What happens to it if you cancel?
Two options: subscription, or buy the unit outright (€699 installed, €629 machine only)
Independent lab test
Ask for a report from an independent lab, not just the manufacturer's spec sheet
Tested by SGS: lead reduced by 99.8 %; it also reduces PFAS and chlorine
Measuring your water (TDS)
Do they measure the dissolved solids (TDS) in your water before and after installing, in front of you?
Yes: we measure your TDS before and after installation and show you both numbers
Remineralisation and tank
Does it add minerals back after osmosis? Does it have a storage tank or is it tankless?
Tankless. Remineralised with calcium, magnesium and potassium; slightly alkaline
Installation and rented flats
What it needs under the sink, whether a tap hole must be drilled, and whether your landlord allows it
Cold-water feed and drain under the sink, and usually a dedicated faucet (a 3-way faucet is an option). Renting? Ask your landlord first
Service area, timing and support
Whether they cover your town, how soon they install, and how you get help when something goes wrong
Barcelona city, Badalona, L'Hospitalet, Sant Cugat and Esplugues; installation usually within 3–7 days; support on WhatsApp
This checklist works for any company; we do not rank anyone. Ask for the answers in writing before you sign. More than 300 Barcelona homes already use Oasly.
Questions when choosing a water filter company
How much does a reverse osmosis filter cost in Barcelona?
It depends on the company and on whether you rent or buy, and some only give a price after a visit. For reference, Oasly costs €24.90 every 4 weeks (about €0.88 a day) or €249 a year in Barcelona city, with installation, filters and maintenance included, or €699 to buy the unit installed. Always compare the all-in yearly total.
Should I buy or rent a reverse osmosis system?
If you buy, you pay once, but filters, the yearly change and any repairs are on you unless you add a maintenance plan. With a subscription, one fee covers all of that. Do the sums over several years with filters and maintenance included. Oasly offers both: subscription, or €629 for the machine only and €699 installed.
What maintenance does a reverse osmosis system need?
Regular filter changes and a check if something goes wrong. With Oasly the filters are changed once a year, included in the subscription. Ask each company how often it changes filters, whether that is included and whether technician visits cost extra.
Can I install one in a rented flat?
Often yes, but ask your landlord first. It needs the cold-water feed and drain under the sink, and usually a dedicated faucet, which means a hole in the worktop or sink. A 3-way faucet avoids a second tap. If drilling isn't allowed, an under-sink filter may not be right for you.
Which areas do you install in?
Barcelona city, Badalona, L'Hospitalet de Llobregat, Sant Cugat del Vallès and Esplugues de Llobregat. Outside these areas, Oasly doesn't install. In Badalona, L'Hospitalet, Sant Cugat and Esplugues the price is €27.90 every 4 weeks or €279 a year.
How long does installation take?
With Oasly, usually 3 to 7 days from booking. When comparing companies, ask for a date, not just "soon", and whether a prior survey visit is needed.
How do I know a filter actually works?
Ask for an independent lab report and for your water's TDS to be measured before and after installation. The Oasly system is tested by SGS (lead reduced by 99.8 %; it also reduces PFAS and chlorine), and we show you both TDS readings. No filter removes 100 % of everything; if someone promises that, ask to see it in writing.
Why remineralise reverse osmosis water?
Reverse osmosis also reduces the minerals that cause limescale, such as calcium and magnesium, so the water can taste flat. That is why Oasly adds calcium, magnesium and potassium back; the water comes out slightly alkaline. Ask each company whether its system remineralises.
Tank or tankless?
A system with a tank stores water that has already been filtered; a tankless one filters as you pour. The Oasly system is tankless and uses about 85 W, only while producing water. Ask what type each company installs and how much space it takes under the sink.
Is Barcelona tap water safe to drink?
Yes. The latest bulletins in the national SINAC system rate the networks serving Barcelona and the four towns we cover as fit for consumption (checked October 2026). A reverse osmosis filter is about taste and limescale, not safety: hardness is not a health problem, but it leaves scale on kettles, taps and appliances.
What Oasly costs
For reference: what Oasly costs, published and with everything included. No minimum term.
Unit, installation, maintenance and yearly filter swap included
The same service in one payment; 13 four-weekly payments add up to €323.70.
€629 machine only, €699 installed in Barcelona
Badalona, L'Hospitalet, Sant Cugat and Esplugues: €27.90 / 4 weeks or €279/year.
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