Tap water or mineral water?

Tap water or mineral water? This question comes up in the supermarket just as it does at the tap at home. In Germany, both meet high quality standards. The differences lie mainly in mineral content, price, taste and environmental footprint. This guide compares the two options point by point. It also shows which minerals tap water contains and when a water filter can be worthwhile.

The comparison is based on 6 criteria that really matter in everyday life: health, mineral content, taste, price, environment and pollutants. Each section clearly sets out the differences.

In Germany, tap water and mineral water are equally healthy. Both are strictly monitored. Tap water is even considered the most strictly controlled foodstuff in the country. More than 500 German mineral waters are bottled directly at the source. Which is the better choice ultimately depends more on mineral content, price, taste and environmental footprint.

The composition of tap water varies depending on where you live. Waterworks use different sources from region to region. Mineral water also differs depending on the producer and bottling. On balance, both generally provide healthy drinking water. So there is only rarely an option that is healthier across the board.

Tap water comes out ahead on price and environmental footprint. Mineral water, on the other hand, can offer higher mineral levels and distinctive nuances of taste. The following sections go through the criteria one by one.

Mineral water is just one of several designations. Food law distinguishes between 4 types of bottled water. Each is subject to its own rules:

• Natural mineral water: comes from a protected underground source and is bottled directly at the source. It is governed by the Mineral and Table Water Ordinance (MTVO).
• Spring water: also comes from a spring, but meets less stringent requirements than natural mineral water.
• Table water: is an industrially blended water and may be produced anywhere.
• Medicinal water: is classed as a medicinal product and is used specifically for prevention or relief.

When people talk about mineral water, they usually mean natural mineral water as defined by the MTVO. Tap water, by contrast, falls under the Drinking Water Ordinance (TrinkwV) and is also legally classed as a foodstuff.

Depending on the region, tap water contains minerals dissolved from rock. They enter the groundwater through weathering. Six substances are particularly relevant: calcium, magnesium, potassium, sodium, iron and sulphate.

Water hardness is determined mainly by calcium and magnesium. Magnesium accounts for 15 to 30% of it. The Deutsche Gesellschaft für Ernährung (DGE, German Nutrition Society) recommends that adults consume around 1,000 milligrams of calcium a day. Potassium is only present in water in bound form. Around 95% of the potassium used goes into fertiliser production. Sulphate comes from sulphur compounds in the soil. The limit set by the Drinking Water Ordinance applies from 250 milligrams per litre, because high levels attack pipes.

Mineral water doesn't get its name for nothing. It often contains more dissolved minerals than tap water, especially calcium, magnesium and sodium. How high the levels are depends on the source. Some mineral waters provide over 100 milligrams of calcium per litre.

Tap water also contributes to mineral requirements. Depending on the hardness level, it contains around 20 to 150 milligrams of calcium and 5 to 50 milligrams of magnesium per litre. However, most minerals come from food. A balanced diet usually covers requirements reliably. Water supplements this intake.

When it comes to taste, the choice is often a personal one. Mineral water tastes different depending on the source and mineral content, and is often also characterised by carbonation. Tap water usually tastes more consistent, and its character depends mainly on the regional hardness. The Drinking Water Ordinance permits up to 0.3 milligrams of chlorine per litre. This can slightly affect the taste in some regions.

Depending on the region, waterworks use chlorine for disinfection. An activated carbon filter reliably binds this chlorine. The aftertaste then fades, and tap water often tastes as mild as a subtle mineral water.

On price, the gap is clear. A litre of tap water costs around 0.2 cents. Mineral water often costs over 50 cents per litre. That adds up.

A person drinks around 1.5 litres a day. Over a year, that costs about 1 euro from the tap. With bought mineral water, it comes to around 270 euros. So anyone who regularly buys bottles is mainly paying extra for the bottle and transport.

In terms of environmental footprint, tap water clearly comes out on top. It comes straight from the tap. There is no packaging or transport. Mineral water, on the other hand, creates additional waste and longer delivery routes.

A study from 2020 compared the two options. A litre of mineral water causes over 200 grams of carbon dioxide (CO₂). Tap water comes to about 0.3 grams per litre. The difference is therefore more than a hundredfold. That makes tap water by far the more environmentally friendly choice for everyday use.

Both types of water are strictly tested for pollutants. Traces can nevertheless occur. In mineral water, they often come from the plastic bottle. In tap water, they are more likely to arise on the way through older pipes.

In 2024, a Columbia University study found an average of around 240,000 nanoplastic particles per litre in bottled water. Tap water is largely free of them. Residues from old lead pipes or copper pipes can be specifically reduced with a filter. This keeps the water clean at the point of use.

The following neutral specialist sources from public authorities and scientific societies serve as the basis. All information on limit values and daily requirements comes from these official and specialist references.