Southern Rural Water is offering vegetable growers at Werribee and Bacchus Marsh another 500 megalitres of water from the Thomson Dam put in reserve for the MID.

It follows a decision by Southern Rural Water in November last year to send 2000 megalitres of water to the west.

But MID's customer consultative committee chairman Graeme Anderson said farmers were not consulted about this latest water allocation, as they were last time.

He said the committee was also concerned about news the water authority was asking the State Water Minister to give Southern Rural Water control of the drought reserve in the Thomson Dam.

Mr Anderson said irrigators were disappointed by the "breaking of mutual trust''.

"We've always been asked and consulted about (water allocations) as a committee... and they've decided to allocate that water without consulting us,'' he said.

"We've been able to add valuable input to decisions in the past by adding the irrigators perspective.

"We've lost confidence in the (SRW) board and the way they're running things at this stage.''

Mr Anderson said while irrigators understood Werribee and Bacchus Marsh farmers were struggling in the drought, the committee also had to consider its own water security.

"We as a committee would be reluctant to let water go out of the reserve this early in the season,'' he said.

"We like to help our fellow farmers but not to the detriment of our own farmers.

"If it doesn't rain between now and August 15 we will be very low on water.

"Southern Rural Water doesn't understand we need to have that water security.''

The Gippsland Times contacted Southern Rural Water for comment but it hadn't responded in time for publication.