"Safety is our number one priority and our crews were on site quickly," a spokesman said.

"A small number of properties will be affected while urgent repairs are made, which are expected to be completed later [Friday] evening."

He said it was too early to tell what caused the break, however noted periods of drought were known to cause pipe expansion and joint movement, resulting in increased water main breaks and leaks.

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Earlier: A spectacular water show erupted on Cowper Street in Warrawong on Friday afternoon, after a water main burst.

The burst mains sent H20 spurting into the air higher than the street pole, right in front of the Warrawong Anglican Church.

Witnesses said the flow began around 4:30pm and was still spurting at 5:15pm.

Sydney Water has been contacted and are currently investigating the issue.

Meantime, a water show of a different kind will cross over parts of the Illawarra with a storm warning issued by the Bureau of Meteorology.