Domestic reverse osmosis: should you remineralise the water?

Glass of pure water in front of a domestic reverse-osmosis unit and its filter cartridges — Reverse osmosis produces very pure — and very lightly mineralised — water. Should it be remineralised?

Reverse osmosis is the most advanced purification technology for domestic drinking water. By forcing water through a semi-permeable membrane, it retains the vast majority of dissolved substances: chlorine, nitrates, pesticides, heavy metals, micropollutants… but also useful minerals such as calcium, magnesium and potassium.

Hence a recurring question — and a frequent sales argument: should osmosed water be remineralised? The honest answer is neither "yes, it is essential" nor "no, it is useless". It depends on what you expect from the water. Let us sort the real benefits from the marketing.

95–99%of dissolved salts retained by the membrane

Ca · Mg · Kminerals largely removed

pH ↓osmosed water slightly acidic

Optionremineralisation, a comfort choice

1. Very pure water… and demineralised

The reverse-osmosis membrane typically retains 95 to 99% of dissolved salts. The result: water of great purity, with a neutral taste, rid of pollutants as well as minerals. Note: a domestic RO unit does not produce fully demineralised water — some traces of mineral salts always remain.

This low mineral content has two direct consequences: a "flatter" taste than that of mineral water, and a slightly acidic pH, which makes the water a little more aggressive. It is on these two points that the remineralisation debate focuses.

Diagram of the water path in an RO unit: tap, prefilters, membrane, optional remineralisation, pure-water tap — The path of water in an RO unit, with the optional remineralisation step.

2. The debate: should you remineralise?

It is a genuine question, on which views differ — including among professionals. Let us honestly present the two points of view.

Arguments for remineralisation (taste, pH, minerals) and arguments to nuance (diet, potability, marketing) — To remineralise or not: the arguments of both camps.

The arguments for

Taste: reintroducing a little calcium and magnesium gives the water "body", often judged more pleasant than fully osmosed water.
pH and corrosivity: remineralisation raises the pH towards neutrality and reduces the aggressive character of the water.
Mineral balance: an intake, however modest, of essential minerals (put forward particularly for people poorly covered by their diet).

The counter-argument

Water is not our main source of minerals: a balanced diet provides most of the calcium, magnesium and potassium the body needs.
Potability is not in question: non-remineralised osmosed water remains perfectly potable.
Beware of purely commercial claims: remineralisation is sometimes oversold as "essential" when it is mainly a matter of comfort.

💡 The right advisory reflex

Present remineralisation for what it is: an improvement of taste and pH, pleasant and relevant for many households, but not a sanitary obligation. Honesty = customer trust.

3. How remineralisation works

In practice, remineralisation is done via a post-filter cartridge installed after the membrane. The osmosed water passes through a mineral media — for example calcite (calcium carbonate), corosex (magnesium) or natural mineral rocks — which gradually releases calcium and magnesium and raises the pH.

It is a step that is simple to add or omit as needed, and a consumable to be replaced periodically like the other cartridges of the RO unit.

Domestic RO unit installed under the sink with its successive cartridges — On an RO unit, remineralisation is added as a post-filter: an extra cartridge placed after the membrane.

4. And the pH / network corrosivity?

Slightly acidic osmosed water is more aggressive. In domestic practice, the RO unit feeds a dedicated pure-water tap (with suitable materials), so the impact on the general plumbing remains limited. But for taste and for drinking water with a balanced pH, remineralisation brings a real plus.

5. Our recommendation by use

Profile / use	Remineralise?	Why
Everyday drinking water	Recommended	Better taste, balanced pH, comfort
Coffee, tea, cooking	Often appreciated	Rounder taste, improved rendering
Technical uses (iron, specific aquarium keeping…)	Rather not	Very pure water is precisely what is sought
"Mandatory for health" argument	To nuance	Diet remains the main source of minerals

🔗 DIMM solutions — Osmosis & remineralisation

DIMM domestic RO units — advanced purification for quality drinking water.
Remineralising cartridges — calcium/magnesium post-filters for taste and pH.
Membranes & consumables — for maintenance and periodic replacement.

6. Who is this choice for?

Individuals & installers

Remineralisation is an excellent comfort argument to offer — provided it is explained honestly as an improvement of taste and pH, not as a vital necessity.

Hospitality & tertiary

For coffee, tea and cooking, remineralised osmosed water offers an often superior taste rendering. To be arbitrated according to the equipment and the use.

Conclusion: a quality choice, not an obligation

Should osmosed water be remineralised? For taste and pH, it is a real plus, which many households will appreciate. For health, it is not essential: non-remineralised osmosed water remains potable, and diet covers most of the mineral needs. The professional's role is to present this choice honestly, without overselling it — that is what builds trust.

The DIMM teams support partner installers, distributors and resellers in choosing RO units and their consumables, remineralisation included, in France and Belgium.

Reference points

Reverse osmosis retains ≈ 95-99% of dissolved salts; domestic osmosed water keeps traces of minerals.
Low-mineral water is slightly acidic and more aggressive; remineralisation raises the pH.
Diet is the main source of calcium, magnesium and potassium.
Common remineralisation media: calcite (calcium), corosex (magnesium), mineral rocks.