The Environment Agency says it will be testing its flood sirens in Calderdale next week.
The agency uses the sirens to warn people in the the Upper Calderdale area when rivers are expected to flood.
There are now eight sirens in the area with an audibility level similar to that used by emergency vehicles.
The sirens will be tested on Friday, April 12 at 10.30am in Todmorden and Walsden, 12.30pm in Hebden Bridge and 2pm in Mytholmroyd.
Each test will last for two minutes. The agency says people do not need to take any action when hearing the sirens at these times.
Loud hailer vehicles will be used to alert people to the tests, ahead of the sirens being sounded.
Environment Agency engagement officer Graham Lindsey said: “Our engineers have replaced three of the sirens in recent weeks. It is important that we test these and the other sirens to check that they are working properly and can be triggered remotely from our incident room in Leeds.
“Although no action needs to be taken during the test, people need to be aware that if they hear the sirens at any other time, then this means that flooding is expected.
“As we saw in the devastating floods in the Calder Valley last summer, flood water is dangerous, particularly in these areas where water cascading down from the steep surrounding hills means flooding can happen very quickly and with little warning.
“Nobody should ever attempt to walk or drive through fast moving flood water and local people should have a flood plan to keep themselves and their families safe.”
Intense rainfall on four occasions last summer resulted in hundreds of properties in Calderdale being flooded. Flash flooding also caused severe disruption to road and rail travel.
The Upper Calder Valley sirens have been installed to complement the Environment Agency’s free Floodline Warnings Direct service, which sends an automatic message by landline, mobile, email or fax to those who have signed up, telling them when flooding is imminent and what action they can take to protect their home or business.
Mr Lindsey added: “If we are expecting the rivers to flood, we will do everything we can to get a timely warning out to people. Unfortunately we are not currently able to warn people of flooding from water pouring down hillsides and roads, from groundwater, or from surcharging drainage and sewer systems.
“However, we would urge people to remain vigilant to local weather conditions and make use of our three-day flood forecast on our website as well as the Met Office severe weather warnings.”
Environment Agency officers will be speaking to residents on the day of the siren tests to check that they heard sirens and also to advise on how to stay safe in a flash flood. Householders and businesses will be able to check whether they are eligible for Floodline Warnings Direct. If they are, they can sign up on the spot for the free service, as well as finding out more about preparing themselves for flooding.
To find out more about the dangers of flood water, and to find out if your property is at risk of flooding and eligible for Floodline Warnings Direct, call the floodline on 0845 988 1188 or visit the website at www.environment-agency.gov.uk/flood.