Filtered tap water vs bottled water: the real maths

A family of four drinks around 1.5 L per person per day, or nearly 2,200 L a year. With bottled mineral water at €0.25 to €0.55/L depending on the brand, the bill quickly climbs to €500–1,200 a year, not counting hauling the packs and storing them. By contrast, tap water in Luxembourg costs around €0.005/L: even filtered by an RO system, the litre comes to a few cents.

An RO system produces near-pure drinking water from the tap, removing nitrates, pesticides, PFAS, lead and chlorine. Against the bottle it wins on running cost, plastic and CO2, at the price of an upfront investment and light maintenance. This table sums up the match, criterion by criterion:

A family switching to filtered tap water typically avoids 1,000 to 1,500 plastic bottles a year. Recent studies have measured tens to hundreds of thousands of micro- and nanoplastic particles per litre of bottled water, whereas reverse osmosis retains nearly all of these particles. On climate, bottled water emits far more CO2 than tap water once you account for making the PET, bottling and road transport.

Before investing, check your water quality with our free diagnostic: it gives your commune's hardness and the parameters to watch. If you live in a farming area or have an infant, the under-sink RO system is the go-to solution for drinking water. For a quote tailored to your commune, our partners at osmoseur.lu install and maintain the system across the Grand Duchy; for limescale throughout the house, adoucisseur-eau.lu steps in alongside.