UPDATE: HEAVY rain has caused chaos across Victoria.

Twelve homes in the Grampians town of Natimuk had to be evacuated because of flash flooding with a relief centre set up for residents at the Soldiers Memorial Hall.

Homes and businesses in Horsham are being sandbagged in preparation for further substantial rainfalls following just over 100ml in the past 24 hours.

Landslides on the Great Ocean Road have also forced road closures in two places between Lorne and Skenes Creek.

Senior Constable Sean Rafferty of Lorne Police said a significant amount of water was on the tourist road from Fairhaven in the state's southwest.

Up to 40 campers in the Wye River and Kennett River areas sought police assistance to move out of the area due to the high volumes of water flooding campsites.

Traffic heading towards Apollo Bay is being diverted to Deans Marsh and Winchelsea and cars heading towards Lorne are being diverted along the Skenes Creek/Forest-Apollo Bay Roads.

The Wimmera Mallee pipeline, which is less than 12 months old and provides water to farmers, homes and businesses the area, burst and lifted from the ground as rainwater drenched the district.

Catchment authority GWMWater spokeswoman Helen Friend said rainfall of up to 170mm in the region had caused four links of the pipe to separate on Wednesday.

"The force of all the stormwater running down the natural watercourse has exposed the pipe and the joins have given way," she told AAP.

"We can't get in there until it dries out to actually fix it."

Ms Friend said rural customers within a five-kilometre radius along Jeparit Rainbow Road between Ellam and Pullut would be affected and would need to rely on farm storage water until the burst is repaired.

The pipeline, which opened in April 2010, normally lies about one metre below the ground.

Premier Ted Baillieu said that while Victoria's flooding was "nothing on the scale of what has happened in Queensland", it didn't mean the flooding was any less dangerous.

"Please stay away from floodwaters, listen to alerts and do whatever you can to stay safe," he said.

"Stay alert, particularly those who are caravanning or on holiday who may not be familiar with a particular locality, they should watch out for warnings and they should stay away from floodwaters."

The State Emergency Service (SES) says up to 150mm of rain is likely to fall over the next three days.

Flood watches have been issued for most of the state, with thunderstorm activity also a possibility in the Central, Western and North Western areas.

The rain is expected to ease tomorrow but will return on Friday with heavy rains with strong winds and the potential for further flash flooding.

Jeparit recorded one of the highest 24-hour rainfall totals with 161mm of rain up to 9am this morning.

Other regions in the Wimmera tipping big totals out of the rain gage include 135mm at Mount William, 104mm at Dimboola and 131mm at Rainbow.

Canary Island, near Kerang, has received 39mm over the past 24 hours, however they have received almost 200mm since Sunday. Their annual average rainfall is almost 370mm.

Premier Ted Baillieu said that while Victoria's flooding was ``nothing on the scale of what has happened in Queensland'', it didn't mean the flooding was any less dangerous.

"Please stay away from floodwaters, listen to alerts and do whatever you can to stay safe,'' he said.

"Stay alert, particularly those who are caravanning or on holiday who may not be familiar with a particular locality, they should watch out for warnings and they should stay away from floodwaters.''

The State Emergency Service says up to 150mm of rain is likely to fall over the next three days.

Flood watches have been issued for most of the state, with thunderstorm activity also a possibility in the Central, Western and North Western areas.

The Wimmera town of Natimuk, west of Horsham, is sand-bagging businesses and Victoria Police have evacuated 12 houses. There is a relief centre at the Soldiers Memorial Hall in town.

Businesses in Horsham are also being sand-bagged.

Further south at Kennett Creek, the caravan park is cut off from town as the creek rises due to flooding.

The Great Ocean Road is closed between Apollo Bay and Lorne according to VicRoads.

Landslides on the Great Ocean Road have also forced road closures in two places between Lorne and Skenes Creek.

Senior Constable Sean Rafferty of Lorne Police said a significant amount of water was on the tourist road from Fairhaven in the state's southwest.

Up to 40 campers in the Wye River and Kennett River areas sought police assistance to move out of the area due to the high volumes of water flooding campsites.

Traffic heading towards Apollo Bay is being diverted to Deans Marsh and Winchelsea and cars heading towards Lorne are being diverted along the Skenes Creek and Forest-Apollo Bay Roads.

Sections of the Western and Wimmera Highways are both closed.

Check VicRoads for more information.

Additional reporting AAP