Highway drainage systems

Following recent rainfall, for the next few weeks we will be prioritising reports of floods that are a risk to road users or property. This means it will take longer than usual to investigate other drainage reports. We apologise for this delay.

Highway drains are designed to:

  • remove surface water run-off from the highway to help keep roads safe and minimise problems
  • prevent damage and make roads last longer through effective drainage
  • minimise surface water from the highway affecting properties or land.

Our highway drains are not usually designed to provide drainage for other areas outside of the highway boundary.


How we look after our drains

We use a risk-based approach to maintaining over 250,000 highway drains and have implemented a cyclical maintenance regime for all roads across the network, which allows us to attend more of our assets in a proactive and cost-effective manner each year.

The drains on our strategic road network will be cleaned annually. Minor roads will be cleaned every one, two or three years, with their cleaning cycle based on risk factors such as:

  • road hierarchy
  • speed limit
  • whether it is a known flood zone.

These factors combined produce individual risk weighting for every minor road across the network, which in turn influences how often we attend.

Find out more about our approach for managing highway infrastructure.

Drains on high-speed roads are checked once a year between April and September.

If a gully is causing flooding or concern, report it to us so that we can investigate the problem.

We are confident our maintenance cycles will enable us to maintain our drainage systems across the county. However, we appreciate people reporting issues to us where they need to be looked at in more detail.

To decide whether to carry out additional works alongside our existing programme, we assess enquiries individually, considering factors such as the:

  • information and evidence provided
  • history of the area
  • date of the next scheduled cleanse
  • potential impact of the issues reported.

Considering these various aspects enables us to determine if immediate action is necessary or if it can be addressed as part of our existing schedule.

If flooding from the highway is causing internal property flooding or making the highway impassable for users, we will attend as an emergency within 2 hours where possible. During extreme events of flash flooding this is unfortunately not always possible.

If we find any defects during routine maintenance these are passed to a drainage engineer for further assessment.

Park your car somewhere else if you see signs telling you that cleansing will take place. We can't clean the drains if your car is in the way.

Don't tip waste, such as concrete and oil, down the drains as this can block the pipes and contaminate nearby streams, rivers and land.

Remove fallen leaves covering gully grills if you can do this safely. When doing this:

  • wear gloves if you are clearing leaves by hand
  • put leaves in your normal rubbish bin or in a compost bin
  • be careful not to step into traffic on the road and be aware of pedestrians
  • don't lift the drain covers or put your hands into the drain as there might be sharp objects you cannot see.

To repair or improve our drainage systems, our work includes:

  • investigation work
  • minor works
  • broken pipe repairs
  • installing and enhancing drainage systems.

Our drainage engineers can carry out specialist work such as CCTV investigations and root cutting in order identify defects and remedy them with the appropriate repairs.

If flooding keeps happening in the same place, we will investigate how the situation can be improved and when we will do the work.

These works are prioritised according to the risk to highway safety and risk to internal property flooding.

If a blocked drain or flooding on a road is causing you concern report it to us.

Other parts of our drainage system

We look also look after ponds, lagoons, pumping stations and soakaways which drain water from the road.

Ditches and grips

Ditches are generally the responsibility of landowners, although these ditches may take highway surface water. If a ditch needs maintenance works we can request landowners to do the required work.

Find out more about  owner responsibility for rivers and ditches

Ponds and lagoons

Some highway drainage systems drain to roadside ponds and lagoons. These are inspected and maintained in response to reports of flooding.

Pumping stations

We own 15 highway pumping stations. These are serviced every 12 months with additional maintenance if needed.


Soakaways are large underground tanks. Water drains from roadside drains, through pipes and into these chambers where it gradually soaks into the ground. If cleaning roadside drains doesn’t clear the flooding, we investigate if nearby soakaways may also need cleansing.