The whole greater Sydney region is in drought but almost a fifth of residents doubt their efforts to save water will have an impact, new research suggests.

Over half of the 1000 Sydneysiders surveyed by Sydney Water wanted to learn more about water-saving techniques but nearly 20 per cent were sceptical they could make a difference.

Greater Sydney is experiencing one of the worst droughts on record and is on level one water restrictions.

According to Sydney Water, dams are less than half full and levels are dropping by almost half a percentage point each week.

But Sydney Water executive Catherine Port says making a difference is easy.

“Just one minute less in the shower, for instance, would save greater Sydney 45 million litres in just one day – that’s enough to fill 18 Olympic swimming pools,” she said in a statement.

Another 28 Olympic swimming pools could be saved if Sydney’s population used the half-flush on their loos once a day.

Anisha Mehra, a teacher from Croydon Park, agrees it’s not difficult to preserve the “very valuable resource”.

She saves water by putting bottles full of sand in her toilet cistern so that it doesn’t wholly fill and therefore doesn’t empty so much with each flush.

Ms Mehra also recommends using shower timers, pin-pricked milk bottles to water plants and never doing half loads of washing.

“Nature has no trade-off, so we have to do our bit,” she told AAP.

Other suggestions include roasting vegetables instead of boiling them, watering plants with bath-water and cooling down at the beach instead of in the shower.

-AAP