These customers will be able to claim multiple water tanks as part of the rebate scheme, at a cost of an extra $500,000 for the State Government.

Eligible stock and domestic customers with multiple house dams on a single account can claim rebates of $1500 to $3000 for each house dam, depending on the capacity of tanks installed.

Victorian Agriculture Minister Joe Helper said changes to the eligibility criteria would provide greater equity to customers who had more than one property.

"Previously, eligible customers could only claim one rebate per GWMWater account, regardless of the number of registered house dams and-or properties identified under the account," he said.

GWMWater will contact all affected customers to inform them of rebate changes. Eligible customers will have until December 31 to install and pay for all tanks.

GWMWater chief executive Peter McManamon welcomed the government's decision.

"This is great news for about 200 of our rural stock and domestic customers who fall into this category," Mr McManamon said.

He said the tank rebate was open to stock and domestic customers who had not received a dam fill from a channel run in the 2006-07 financial year.