"As I see it, regional council knew that what happened on April 6 [a section of the Rangitaiki River bursting through the stop bank] had been a possibility for some time, and that makes them liable.
"Each week we receive more information to strengthen our case."
Mr Josephson and Mr Heaney are in Edgecumbe and have spent the better part of this week talking to people who have agreed to be part of the lawsuit.
"They're sitting down for up to two hours with each of the people/families, and ascertaining loss. There's a lot of groundwork going on right now and we know it will be a long time before there is a result, but we want to do it once and do it right."
Mr Bourk said a top New Zealand engineer had been engaged by those associated with the lawsuit, and had undertaken an assessment of the April 6 events.
Meanwhile the independent review team, commissioned by the regional council in the days after the event to look into the infrastructure and circumstances leading to the breach, is still carrying out its work.
The regional council review was to have been completed by the end of July but the team requested more time.
"The outcome of regional council's review findings will have no influence over the class action suit," Mr Bourk said.
The first of Wednesday's class action public meetings begins at 6.30pm at St David's Hall on College Rd. The second starts at 7.30 at the same venue and is more specifically for farmers and other business owners.