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Where Water Comes From

Water pouring into glass

Essentially all of our water in Scotland comes from rain, and we certainly get more than our fair share's worth of that!

When it rains two things can happen:

The water can flow into streams, rivers, lochs and reservoirs, and this type of water is known as surface water,

Alternatively, the water can also seep through the ground until it passes through. It then forms pools and this type of water is known as ground water. It is often very pure as many of the pollutants are naturally filtered out through the seeping process.

Some Scottish Water customers are supplied with water from ground water sources, however, most of our customers receive their tap water from surface water sources.

Why does water need to be treated?

We can't live without water and we depend upon it for nearly everything that we do. If water carries a disease-producing bacteria, this could seriously damage your health. As a result, the main aim of our treatment process is to remove any harmful bacteria and ensure your water is safe for you to use and drink.

Water quality and the law

There are very strict laws that govern drinking water quality in the UK. The water that we supply to our customers must meet high standards set by the government and the European Union. To ensure that the water at your taps meets these quality targets we regularly sample and test the water both at the treatment works and at customers' taps.

These sample results are available at your Regional Scottish Water office.

How do we make your water safe?

The way we treat your water depends on where it has come from. Surface and ground waters do contain some naturally occurring substances, as seen previously. Each water source will have unique characteristics and requires a tailored treatment process to ensure that it is safe for you to drink.

A typical treatment process

1. screening

Once the water has been piped to our treatment works it is then passed through mesh screens to remove any leaves and debris.

2. aeration

Odours and some dissolved gases are eliminated and metal salts are oxidised to allow them to filter more easily.

3. clarification

Just prior to clarification a chemical coagulant is added. This reacts with the water to form loosely connected 'super particles' called a floc, which settles and carries any suspended particles with it. The floc also traps bacteria and absorbs colour, and as it settles it forms a sludge which is removed for disposal leaving behind clarified water.

4. filtration

The clarified water is then filtered to remove any remaining particles before disinfectant is added.

5. disinfection

A disinfectant, usually chlorine, is then added, as this is the most effective and reliable way of ensuring that your water is safe to drink. In carefully controlled doses chlorine is deadly to bacteria but is harmless to humans. It has been used in water supplies since 1897.

6. pH Adjustment

pH is a scientific term used to describe the acidity or alkalinity of a substance. We have to control the level in your water supply to make sure that it does not corrode the metal pipes in the distribution system by being too acidic, or leave deposits on the pipes by being too alkaline.

Your water is now clear, safe and ready to drink. The water is then pumped into our vast network of pipes ready to flow down our water mains to your taps. See our Water Quality section for more information.