Home reverse osmosis: the savings your installer won't mention
Replacing reverse osmosis filters costs €200 with an installer or €50 DIY. The resulting water is ultrapure and acidic. Is it worth it? Data and warnings.
English · Original discussion in Spanish · Published
Reverse osmosis: savings or a replacement-parts business?
A home reverse osmosis system costs €1,500 with a water softener. The installer's first filter change: €200. Doing it yourself: under €50. The difference is 75% cheaper, but that's not the industry's only blind spot.
A real case: after years paying for brand-name servicing, a user found a supplier of generic replacement parts and changed the filters in 20 minutes. Standard 5-micron cartridges cost from €3.50 each. Installers charge up to €120 for a service that barely requires removing and replacing parts. The business isn't in the machine, it's in the consumables.
Meanwhile, osmosis water raises questions: with mineral salts removed, the pH drops to 5-6 and conductivity falls from 500-2000 microSiemens/cm (drinking water) to 5-200. Those who use it for aquariums know that, without remineralization, it kills fish through deionization. For human consumption, some warn that "too pure" water can leach ions from the body. While a glass won't kill you, the long-term effects of the lack of minerals are debatable.
Reject water, up to three times the volume produced, is wasted. Building a bypass to recover some of it and raise conductivity is a home-made solution few people know about.
Real savings do exist, but only if you avoid falling into the official-maintenance trap. The surprising figure: a laboratory water testing kit costs less than what the installer charges for a single visit.
The hidden cost of ultrapure water
Each filter change can cost between €50 (DIY) and €200 (installer). Manufacturers recommend annual replacements. Add a water softener, which consumes bags of salt every three months (about €30 per bag), and annual costs skyrocket. But many users report that osmosis water tastes fizzy (dissolved CO2) and is acidic, which has led some to install remineralizing post-filters that add yet another cost.
Health: risk or myth?
The myth that pure osmosis water is "deadly" circulates persistently. The reality is that the human body gets its minerals mainly from food, not from water. The WHO has noted that demineralized water is not ideal in the long term, but there are no conclusive studies on harm from household consumption. The debate remains open, and everyone decides whether to pay for "neutral" water or put up with the hardness of tap water.
Related discussions in the forum
A home reverse osmosis system costs €1,500 with a water softener. The installer's first filter change: €200. Doing it yourself: under €50. The difference is 75% cheaper, but that's not the industry's only blind spot.
A real case: after years paying for brand-name servicing, a user found a supplier of generic replacement parts and changed the filters in 20 minutes. Standard 5-micron cartridges cost from €3.50 each. Installers charge up to €120 for a service that barely requires removing and replacing parts. The business isn't in the machine, it's in the consumables.
Meanwhile, osmosis water raises questions: with mineral salts removed, the pH drops to 5-6 and conductivity falls from 500-2000 microSiemens/cm (drinking water) to 5-200. Those who use it for aquariums know that, without remineralization, it kills fish through deionization. For human consumption, some warn that "too pure" water can leach ions from the body. While a glass won't kill you, the long-term effects of the lack of minerals are debatable.
Reject water, up to three times the volume produced, is wasted. Building a bypass to recover some of it and raise conductivity is a home-made solution few people know about.
Real savings do exist, but only if you avoid falling into the official-maintenance trap. The surprising figure: a laboratory water testing kit costs less than what the installer charges for a single visit.
The hidden cost of ultrapure water
Each filter change can cost between €50 (DIY) and €200 (installer). Manufacturers recommend annual replacements. Add a water softener, which consumes bags of salt every three months (about €30 per bag), and annual costs skyrocket. But many users report that osmosis water tastes fizzy (dissolved CO2) and is acidic, which has led some to install remineralizing post-filters that add yet another cost.
Health: risk or myth?
The myth that pure osmosis water is "deadly" circulates persistently. The reality is that the human body gets its minerals mainly from food, not from water. The WHO has noted that demineralized water is not ideal in the long term, but there are no conclusive studies on harm from household consumption. The debate remains open, and everyone decides whether to pay for "neutral" water or put up with the hardness of tap water.
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Summary of a discussion on Burbuja.info - Foro de economía, actualidad y política., translated from Spanish and reviewed before publication. Read the full discussion (34 replies).
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