Acids are a major part and problem with modern diets, and they can cause damage to our dental and digestive health, which is why many people avoid acidic foods and drinks and opt for more neutral or alkaline foods to redress the balance, as well as using water ionisers to drink more alkali water.

However, many tap waters and bottled water brands are also predominantly acidic, with a study finding that of 14 bottled waters they tested, 10 were acidic.

Tap water can vary quite strongly, with water quality regulations specifying that tap water can be as acidic as 6.5 pH and still be considered safe.

Part of the reason for this is that water passes over and through the ground, which is made up of different minerals and stones that can increase alkalinity, as well as plants and organic material that give off carbon dioxide and make water more acidic.

As well as this, acid rain, outright water pollution and the drainage of mines can also be a factor in affecting water levels.

Acid levels can actually vary during the day, and water is at its most acidic during the night and early in the morning, as carbon dioxide respiration creates a mild acid, but once the sun rises, photosynthesis consumes this carbon dioxide and increase the pH level.

Generally, you can taste the difference, with more acidic water tasting almost metallic, whilst alkaline water has a different concentration that is closer to hard water.

Water hardness is often connected to its pH level because hard water tends to contain higher amounts of magnesium and calcium, both of which are alkalines.