Driving on flooded roads: should you drive through flood water?
After heavy rain the road ahead disappears under water. Decide whether to go on, and what to check if you have driven through water.
The short version
- Wet road: at least double the gap.
- Do not drive through flood water. Turn round and find another way.
- After deep water, test your brakes gently.
Step 1
The road is wet after heavy rain. How should you change your driving?
✓ Slow down and leave at least double your normal gap. Stopping distances are at least double on a wet road, and tyres grip less.
Why not the other options
- ✗ Nothing, modern tyres cope with water. Tyres help but cannot beat physics. Water at speed can make the steering go light.
- ✗ Drive closer to the car ahead to follow its tyre tracks. A shorter gap is the opposite of what you need when it takes twice as long to stop.
- ✗ Turn on your hazard lights. Hazard lights are not for driving in rain. Use dipped headlights if visibility drops.
Step 2
The road dips ahead and is under water. You cannot see how deep it is.
What do you do?
✓ Do not drive into it. Turn round when it is safe and find another way. Flood water hides how deep it is, damaged road, open drains and debris. A small car can float in surprisingly shallow moving water.
Why not the other options
- ✗ Drive through fast so you do not stall. Speed throws up a bow wave that can flood the engine, and you will hit anything hidden at speed.
- ✗ Follow the line of the cat's eyes and keep going. Knowing where the road is does not tell you how deep the water is or whether the road is still there.
- ✗ Get out and wade in to check the depth. Flood water can be fast, contaminated and hide open drains. Stay out of it.
Step 3
A tall 4x4 drives through towards you and makes it across.
Does that mean your car can make it?
✓ No. A taller car can survive water that would stall or float yours. Your air intake, doors and weight are all different. The safe choice is still another route.
Why not the other options
- ✗ Yes, if they made it the water is safe. Their height and weight are nothing like a small car's. The depth also varies across the road.
- ✗ Yes, if you go right behind them in their wake. Their bow wave would push water straight into your engine.
- ✗ Yes, as long as you keep the windows open. Open windows do not keep the engine dry or stop the car floating.
Step 4
Another time, you have just driven through a deep ford that you know well.
What should you do straight after?
✓ Test your brakes gently at the first safe chance. Wet brakes may not work properly. Press gently to check, and if they feel weak, brake lightly while driving slowly to dry them.
Why not the other options
- ✗ Brake hard to dry them quickly. If they are not working properly, a hard stop is exactly what you cannot rely on. Test them gently.
- ✗ Speed up to blow the water off. Going faster before you know the brakes work is the wrong way round.
- ✗ Nothing, brakes are sealed. They are not sealed. Water reduces their grip until they dry.
The rules behind it
- Rule 227 In the wet, stopping distances are at least double those on a dry road.
- GOV.UK flood advice Do not drive through flood water. It can hide damaged roads and open drains, and only move your car if it is safe.
- Rule 121 After driving through deep water your brakes may not work well. Test them gently at the first safe chance.
More situations
Based on the Highway Code and the Road Traffic Act 1988 as published on GOV.UK in October 2026, in our own words; follow the links for the full text. Insurance points are common UK insurer policy terms, so check your own policy. This is not legal advice. Contains public sector information licensed under the Open Government Licence v3.0.