The flow of running water in the port city of Cape Town has been affected by a wider pattern of climate change

(Recasts with national disaster declaration)

JOHANNESBURG, Feb 13 (Reuters) - South Africa has declared a national disaster over the drought afflicting southern and western regions including Cape Town, though the city pushed back its "Day Zero", the day the city's taps will run dry.

The flow of running water in the port city of 4 million has been affected by a wider pattern of climate change seen around the country including the Western Cape, where Cape Town is located, the Northern Cape and Eastern Cape provinces.

Supplies have yet to recover from an El Nino-triggered drought two years ago, heralding a potential shortage that could hit industrial and agricultural output.

The Department of Cooperative Governance and Traditional Affairs said after re-evaluating the magnitude and severity of the drought that it had reclassified it as a "national disaster". The department had said last week it was close to making such a declaration.

Cape Town, whose oceanfront location is a major tourist draw, has pushed back its designated "Day Zero", when residents will have to start queuing for water, to June 4 from May 11, with officials citing a decline in water usage by residents.

Deputy Mayor Ian Neilson said that over the past week, water consumption in Cape Town had declined to 526 million litres per day. This was the first time the daily average has been kept under 550 million litres, he said, citing city efforts to regulate the flow of water and residents' cooperation with official appeals to curb their consumption.

Cape Town hotels have asked guests not to use baths and to limit showers to two minutes or less, while some restaurants are switching to disposable cups and ditching table linen.

(Reporting by James Macharia; editing by Mark Heinrich)

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