Q&A: What happens when there is a drought

Another 17 English counties are now experiencing a drought.

The Environment Agency has added the whole of the Midlands and south-west England to its list of areas in drought, joining south-east England, eastern England and parts of Yorkshire.

It is also forecasting that drought conditions could last until Christmas.

So far the threat of water shortages is not affecting the whole of the UK.

In Scotland reservoirs are between 93% and 97% full, while in some parts of south-east England levels are lower than in the notoriously dry summer of 1976.

But what does being in drought actually mean - and what happens once one has been declared?

What is a drought?

A drought occurs when a period of low rainfall creates a shortage for people, the environment, agriculture or industry.

What factors determine whether the UK is suffering a drought?

Water companies and authorities use four tests to decide whether a drought has begun:

• Hydrological thresholds, including rainfall, river levels and flows and reservoir storage
• Environmental indicators, such as water quality
• Levels of customer demand
• Management actions, such as whether emergency measures are needed

Do water companies plan for a drought?

Yes. Every five years all water companies in England and Wales have a duty to prepare 25-year plans showing how they will manage their water resources into the future, including collecting, storing and transporting water to meet demand during a drought.

The Scottish water authority and the Northern Ireland water authority have the responsibility for devising, maintaining and implementing drought plans for their areas of the UK.

What happens when a drought is declared?

Water companies and authorities follow a sequence of actions of increasing severity:

Step 1. Water companies and authorities begin to make changes to the way they operate water supply systems to conserve water in order to meet customer demands.

In addition publicity campaigns are launched to encourage people and businesses to reduce demand for water.

Step 2. Water companies and authorities introduce restrictions on using hosepipes for garden watering and car washing, and have the option of banning the use of pressure washers, filling pools and hot tubs. People can still use a watering can for plants and a bucket to wash their cars.

In addition the Environment Agency can restrict or ban agricultural spray irrigation in England and Wales.

Step 3. Drought orders or drought permits are granted either by the Environment Agency, the Scottish government or the Northern Ireland assembly to allow water companies and authorities to restrict certain types of water use.

These are called "non-essential use ban drought orders", and cover things such as the filling of ornamental ponds, cleaning the outsides of buildings (other than windows), operating mechanical vehicle washers and using mains water in a hosepipe or sprinkler to water gardens, lawns, verges, other landscaped areas, allotments, parks or any surfaces used for sport or recreation. This applies to both business and domestic customers.

Step 4. Water companies and authorities apply to restrict water demand by using standpipes or bowsers, or by cutting supplies for limited periods. This has not been done across the UK since the drought of 1976.

What is the current situation?

The Environment Agency is reporting that:

• East Anglia, south-east of England, south and east Yorkshire, the Midlands and south-west England are in drought
• The counties now officially in drought status are: Lincolnshire, Cambridgeshire, parts of Bedfordshire and Northamptonshire and west Norfolk (all in drought since summer 2011); Hampshire, West Sussex, East Sussex, Kent, Surrey, London, Berkshire, parts of Hertfordshire, Buckinghamshire, Oxfordshire, and the east of Gloucestershire (all in drought since February 2012); areas from Sheffield in the south of Yorkshire to Scarborough in the east, plus areas around Doncaster, Hull and Driffield (in drought from March 2012); Nottinghamshire, Leicestershire, Derbyshire, Staffordshire, West Midlands, Warwickshire, Shropshire, Worcestershire, all of Herefordshire, south and west Gloucestershire, Cornwall, Devon, Dorset, Somerset, Bristol, parts of Hampshire and most of Wiltshire (in drought from April 2012)
• View a map of those areas of the UK at risk from drought in 2012 (PDF)
• More on dealing with drought from the Environment Agency