By TAMMY WEBBER Associated Press

Australia's wildfires have illuminated a growing global concern over water quality.

That's because forests, grasslands and other natural areas that supply drinking water to millions of people are increasingly vulnerable to fire in a hotter, drier world.

More than 60%t of the water for the world's 100 largest cities originates in fire-prone watersheds _ and countless smaller communities also rely on surface water.

But storms can dump far more water in a shorter period than in the past.

That means ash, sediment and debris from burned areas can quickly wash into waterways and reservoirs.

Affected areas include the Western U.S., where 65% of water supplies originate in forested watersheds.

Experts say communities need to prepare for more impacts in the future.