Drilling is expected to take two weeks

Drilling in the grounds of the Royal Chelsea Hospital, west London, is expected to take two weeks.

It is hoped it will provide 4,400 gallons (20,000 litres) a day for water features and irrigating exhibits.

Organisers said they were sourcing water wisely but still putting on a "show stopping event" from 23-27 May.

At a cost of �45,000 a 30ft-high (10m) drilling rig has been set up to bore through chalk and clay to a water-table which is lower than the River Thames.

This borehole will also provide us with a long term sustainable solution to access water wisely and responsibly in the future Bob Sweet, organiser of RHS Chelsea Flower Show

A pump will then be lowered into the borehole to extract the water which will be stored in two underground tanks.

Exhibitors will then be able to access this water by using standpipes across the showground.

Bob Sweet, organiser of the RHS Chelsea Flower Show, said they had taken the measures after implementing a voluntary hosepipe ban.

"We are delighted that we have been able... to find this reliable and sustainable solution to a potential water shortage and to provide water for the show's essential needs.

"This borehole will also provide us with a long-term sustainable solution to access water wisely and responsibly in the future."