A Closer Look at Dry Residue in Water

Dry residue in water: definition, ideal levels, and tips for choosing the best drinking water

The dry residue is a key indicator for understanding the quality of the water you drink. It reflects the total amount of minerals and dissolved elements remaining after evaporation. Here, you will learn how to read this value, why it matters for your health, and how RO water can improve your daily hydration.

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Dry residue: what exactly is it?

The dry residue is the amount of minerals and dissolved substances in water that remain after complete evaporation at 180°C.

It is expressed in mg/L. It is very simple: you heat 1 liter of water, then weigh what remains.

This figure therefore reflects the water's overall mineral content.

What amount of dry residue is ideal?

Very low mineral content	< 50 mg/L
Low mineral content	50 to 500 mg/L
Moderate mineral content	500 to 1,500 mg/L
High mineral content	> 1,500 mg/L

For daily consumption, specialists recommend water with < 100 mg/L.

Why choose water with a very low mineral content?

Contrary to popular belief, water with a low mineral content is better suited to daily use. It:

better supports toxin elimination
is gentler on your kidneys
prevents chronic mineral overload

Mineral-rich waters should not be consumed every day: historically, they were sold… in pharmacies.

How should you choose your water?

Check the label: choose < 100 mg/L
Avoid drinking highly mineralized water daily
Remember: water helps cleanse your body

Dry residue and RO water

Water produced by a reverse osmosis system generally has: 10 to 50 mg/L of dry residue

This falls squarely within the ideal range for healthy daily hydration.

FAQ – Dry residue

Dry residue = TDS?

Dry residue is related to TDS (Total Dissolved Solids), but they are not identical. TDS measures all dissolved particles, while dry residue represents their mass after evaporation.

Is water with a very low mineral content bad for you?

No, that is an old myth. Water with a low mineral content helps your body flush out waste. Beneficial minerals come primarily from your diet.

Do RO systems remove too many minerals?

They remove excess minerals — easing the burden on your body. What matters is not the quantity but the quality of the minerals absorbed (those in food are bioavailable, unlike those in water).