Reverse osmosis water is safe to drink and is what a great many households drink every day. The concerns raised about it are real but modest, and they are about taste and mineral content rather than safety. The more useful question, and the one people rarely ask, is how you know the system is still doing what it did when it was fitted.
The direct answer
A membrane rejects most dissolved material, including a long list of contaminants, and passes water. There is nothing harmful about the result, and reverse osmosis is used to produce drinking water at every scale from a kitchen cabinet to a municipality. Fresh permeate is slightly acidic and very low in dissolved minerals, which is what gives it a flat taste, and a remineralization cartridge fitted last addresses both the taste and the mild aggressiveness towards metals that demineralized water has.
The mineral question, in proportion
The objection raised is that water stripped of calcium and magnesium removes a dietary source of both. The USGS describes hardness as exactly those two minerals, and reverse osmosis removes them along with everything else. For someone eating normally, food supplies the great majority of intake and water a small share, so this is not a route to deficiency. It is a fairer consideration where a diet is already low in those minerals, and it is another argument for the remineralization stage.
Infant formula and specific cases
Reverse osmosis water is commonly used for making up infant formula and is well suited to it, since it removes contaminants that matter most at that age, including nitrate and lead. Where a household is following specific medical or paediatric guidance, that guidance takes precedence over any general statement here. The same applies to anyone advised on mineral intake for a health reason: the water is a small part of a larger picture and worth discussing rather than deciding from a product page.
Knowing the system is still working
This is the part that matters in practice, because a membrane fails gradually and silently. Compare a dissolved solids reading of the feed water with one taken from the membrane output before the storage tank: a wide gap means the membrane is rejecting properly, and converging readings mean it is finished and the household has been drinking barely treated water. Change prefilters on schedule, since carbon protects the membrane from chlorine. Our reverse osmosis guide covers maintenance in full.
Questions people ask about can you drink reverse osmosis water
Is reverse osmosis water safe to drink?
Yes. The objections concern taste and mineral content rather than safety, and both are addressed by a remineralization stage.
Will it cause a mineral deficiency?
Not for someone eating normally, since food supplies the great majority of calcium and magnesium intake.
Can it be used for infant formula?
It is commonly used and well suited, since it removes contaminants that matter at that age. Follow any specific paediatric guidance you have been given.
How do I know the system is still working?
Compare feed and product dissolved solids readings, taking the product sample before the tank. Converging readings mean the membrane is spent.