Over the last six months, the area has seen just 65 per cent of the long-term average amount of rain expected for the period.
In Havant, the last month brought just 5mm of rain – but a record-breaking heatwave started the month with scorching sunshine across the region.
A spokesman from the company warned that it ‘may require extra measures in certain areas where water is scarcer and the pressure on supply is greatest, such as Hampshire and the Isle of Wight’.
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He added: ‘We are working closely with local communities and partner agencies in these areas, to keep disruption to a minimum.
‘We're proud to deliver a reliable water supply, whatever the weather, so we ask all customers to help us do that by using water wisely at all times. We share tips and advice on ways to save water our social media platforms and website. We also encourage households to use our GetWaterFit water saving calculator.’
Portsmouth Water, which supplies water across the city and the surrounding towns, called on customers to use water ‘wisely’ – as the area is not set to receive any significant rainfall in the coming weeks.
Bob Taylor, chief executive of Portsmouth Water said: ‘Whilst I can reassure you, we are not facing an immediate risk to our water supply, there is no significant rain currently on the long-range forecast and so, being prudent, I would like to ask all our customers to think about how they use water - and to use it wisely.
‘We really appreciate all the support we have already received from our customers through the recent spell of exceptionally hot weather.’
Residents are encouraged to save water by watering plants and gardens using a bucket or a watering can rather than a hose.
Water companies also advise customer to refrain from using garden sprinkler, avoid washing your car other than its glass and mirrors, and reuse bathwater in the garden.
A shower will save more water than a bath – a typical bath uses 80 litres of water, while a four minute shower could use less than 50.
The hose pipe ban will begin on August 5 at 5pm and continue until further notification.
Any person who breaks the restrictions – which include prohibitions on using a hose to water your garden or clean vehicles, patios, or walls – may be guilty of an offence, and may be fined up £1,000.
The last widespread hose pipe ban was introduced 2012, when seven areas including Southern, Anglian and Thames Water imposed restrictions.
Earlier this month, Portsmouth baked in temperatures as high as 32 degrees, and The Met Office has warned that the UK faces ‘very hot’ spells of weather in August.