Concerns of bushfires' debris could be washed into Sydney Dam.

Rain expected to hit eastern New South Wales tomorrow will provide some reprieve to firefighters.But there are concerns it could wash ash and debris into Sydney’s main water supply, which more than five million people rely on.

Warragamba Dam recouped a year's worth of water in one weekend, rising 17.7 per cent to sit at 60.7 per cent at 10.30am on Monday. Source: AAP Image/Dean Lewins