Pushing for Warragamba solution, flood protection campaigner John Miller in Windsor. For others, the increase is harder to fathom. One resident of Seven Hills in Sydney's west, was told by NRMA that her annual premium would more than triple to $3600 even though the council rates her house as having less than a one-in-10,000 year risk of flooding. Big wets to blame Insurers blame the increases on the spate of flooding across much of eastern Australia in recent years including a $2.5 billion billion bill for the 2011 Queensland floods - with another $733 million hit from January's big wet in Queensland and NSW. "In some cases, we may have updated our flood mapping or are now able to better identify a property's exact location on a block," Andy Cornish, chief executive of NRMA, explaining the premium hikes. Mr Whelan said 2 per cent of Australian homes are at "extreme risk" from flooding. The industry knows where they are and will price accordingly - even if that makes policies unaffordable. "Insurance is a very real issue" with annual premiums costing as much as $10,000, he said. Mitigating circumstances The issue of those most needing flood insurance being unable to pay for it may come to a head next month when the federal government is due to respond to the Productivity Commission's report on barriers to effective climate change adaptation. Catastrophes cost insurers almost $10 billion in the five years to 2012, triple the previous five years" level, and are expected to climb as a warming atmosphere makes intense rainfall events more likely, climate scientists say. Flood mitigation efforts may focus on regions such as the Nepean-Hawkesbury valley. It is "potentially one of the most at-risk areas from flooding in Australia," according to ICA's Mr Whelan. John Miller, the 83 year-old spokesman of the local flood mitigation action committee, has campaigned for decades to have the wall of the Warragamba Dam raised 23 metres, as outlined in a 1995 environmental impact study. The contruction cost, now about $500 million, should be weighed against exposing at least 56,000 homes flooding in the event of a repeat of the monster flood of 1867. A flood that size would cost "far more than Queensland has ever seen," he said. We're trying to get the money before the flood. Flood way On McGrath Road at McGrath's Hill just south of Windsor, houses must be built to two storeys. Even so premiums for some houses have increased six-fold in the past year from $1200 to $8000. Barbara Harris, a nearby resident has a particular reason to worry about floods. Her insurer, NRMA, recently hiked the annual cost of her premium including flood coverage from $840 to $4800, forcing her to drop protection from inundation. One friend was offered flood coverage for $10,000 a year. "Most people can't afford insurance," Ms Harris said. It's beyond anybody's pocket. At a height of 16 metres above the nearby South Creek, the base of Ms Harris's house is roughly at the one-in-100 year flood level. However, Ms Harris says earthworks by neighbours and nearby road construction mean her horse paddocks and buildings are at greater risk - just as insurance is being priced out of her reach. "It's definitely more vulnerable," she said. If we do get a big flood, we'll be gone. Ms Harris, who uncle Bill Harris was an engineer on the giant Warragamba Dam during its construction more than 50 years ago, said she has little choice but to stay put and hope the 21-year abeyance of major flooding of the Hawkesbury River continues. "If the floods come, nobody is going to want to buy there," she said.