The Science Bit

TDS and Mineral Content

The common method of comparing waters is to use the chemical composition. However as ground waters contain a large number of chemical constituents, classification using these can be very difficult. The simplest and the most useful is in terms of Total Dissolved Solids (TDS). TDS is a measure of dissolved minerals in a sample of water and is often quoted on the label as ‘dry residue’.

The water is heated to 180°C until all of the water evaporates, leaving a dry residue that can be weighed. Waters are classified as follows:

Category TDS Range (mg/litre)
Very lightly mineralised 0-50
Lightly mineralised 50-500
Medium mineralisation 500-1500
High mineralisation More than 1500

Highland Spring Water is classified as lightly mineralised with a dry residue of 170/180mg/l.

Originating page (Sodium)


The Food Standards Agency quotes a recommended maximum daily intake of Sodium of 2.4 grammes (which is equivalent to 6g Salt).

The Sodium content of our water is currently very low at 5.6 milligrammes per litre; therefore 1Litre of Highland Spring represents 0.23% of your recommended daily allowance. (1 gramme = 1000 milligrammes).

Originating page (pH Levels of Highland Spring)
The Science Bit - Bottle with pH levels
Originating page (Packaging and BPA)

Packaging and BPA

The plastic bottles used for Highland Spring water are made of PET (Polyethylene Terephthalate), which is the best plastic material available, and which has been scientifically demonstrated as safe for use with food and drinks.

There is no Bisphenol A (BPA) in PET bottles. Rigorous food safety testing and regulation ensures its continued safety.