Emergency services have worked late into the night to try to clear the water from roads and railway lines in Todmorden in West Yorkshire.
Parts of the market town were left under one and half feet of water.
Police have asked people to avoid areas that were badly affected and said that waves from driving through the water can damage houses.
They have also issued a warning for people not to cross a bridge in the town they believe may have been damaged.
Torrential rain and flash flooding has hit areas of West Yorkshire today.
Parts of the market town of Todmorden are currently under one and half feet of water.
This follows a day of heavy, slow moving and thundery showers across the UK.
West Yorkshire Police have issued a warning to people asking them to avoid affected areas including Todmorden.
There has been major flash flooding in Walsden and Todmorden tonight. Here are the pictures from our reporter on the ground, Chris Kiddey.
Motorists are being advised to avoid floodwater in Todmorden and Hebden Bridge as both places have suffered from a torrential downpour.
West Yorkshire Police Police say the device in Horbury was found to be safe, and the grenade was not filled with any explosive. The police cordon is being lifted and residents who were evacuated are being allowed back to their homes.
West Yorkshire Police are investigating reports of an unexploded hand grenade in Horbury, between Huddersfield and Pontefract. Buildings in the immediate area have been evacuated as a precaution, and the Army's bomb disposal unit is on its way to the scene.
A football fan who was filmed attempting to punch a police horse has told ITV News that he is ashamed of his actions.Read the full story ›
The man seen punching a police horse during the football violence in Newcastle at the weekend has insisted he is an animal lover.
Barry Rogerson, 45, from Morpeth in Northumberland, was caught on camera lashing out at a police horse before he was hauled to the ground by officers.
Speaking to newspapers today, the unemployed factory worker accepted he acted stupidly, but said the horse startled him and made him panic.
He told the Daily Mirror: "I reacted stupidly. I did not go out to attack a horse.
"I love animals - I've got three dogs, a fish pond out the back and I feed foxes across the road."
He said the pictures made the incident look worse than it was but that he had no excuse.
West Yorkshire Police have tweeted that Police Horse Bud has received dozens of messages of support in the post. Bud was attacked in football riots in Newcastle at the weekend.
A West Yorkshire Police horse who was attacked in football riots at the weekend is back recovering in his paddock today. This was Bud at home in Wakefield this morning - after his ordeal in Newcastle yesterday
He was controlling crowds at the Newcastle versus Sunderland match when a fan apparently tried to punch him. His alleged attacker was arrested and bailed. Bud's handlers say he's now doing well.