Preventing agricultural pollution in exceptional circumstances

Spreading slurry and milk on agricultural land: Environment Agency advice in exceptional circumstances such as extreme weather.

Applies to England

You can cause soil damage and water pollution if you spread slurry or milk during exceptional weather or on unfavourable soil. The risks are much greater than in more usual conditions.

You must contact the Environment Agency if:

You can only spread milk to land if you have a U10 waste exemption.

Definition of exceptional circumstances

Exceptional circumstances are those that are not common, usual or reasonably expected. For example:

  • the long exceptionally dry summers of 1976 and 2018
  • major flooding
  • major disruptions to agriculture and food supply

It does not apply to circumstances that can be planned for. For example, wetter than average winter rainfall.

Contingency plan

You must have a contingency plan to avoid causing pollution during exceptional circumstances.

You must make sure that all your staff and contractors are aware of your contingency plan. It should include field inspections to consider the risk of slurry or milk getting into surface water or groundwater.

Work with neighbouring farms to create your contingency plan if possible.

Use the following hierarchy of options to make your contingency plan. 1 is the most favourable and 5 is the least favourable.

  1. Store the slurry or milk at the place of production.
  2. Store the slurry or milk at the place of use.
  3. Dispose of the slurry or milk at an off-site anaerobic digestion plant or other effluent treatment plant, including at a sewage treatment works - milk can only go to permitted anaerobic digestion sites.
  4. Store the slurry or milk off-site.
  5. Spread the slurry or milk on low run-off risk land.

Reducing the amount of slurry you produce

During exceptional circumstances you should reduce the amount of slurry (including lightly fouled water) you produce. You should:

  • wash dairy parlours down with a low volume hose system (0.6 cubic metres per cow per month or 20 litres per cow per day)
  • remove excess dung with a brush or squeegee before hosing down to reduce the amount of wash water you need to use
  • keep animals on straw to produce solid manure rather than slurry
  • divert uncontaminated surface water away from dirty yards
  • keep or move livestock onto the smallest yard area necessary
  • install, maintain or repair gutters and downpipes, especially on roofs that drain onto dirty yards
  • consider covering exposed fouled yard areas

Temporary slurry storage

You must normally comply with SSAFO rules to store slurry.

However, the Environment Agency will waive the full SSAFO requirements if you want to store slurry for less than 12 months. You must only consider temporary storage where existing facilities are inadequate.

Temporary storage could include:

  • reinstating disused stores
  • reclaiming tanks
  • new tanks
  • earth bank lagoons
  • lined lagoons
  • slurry bags

To keep slurry in a temporary store you must:

  • check planning requirements with your local planning authority
  • contact the Environment Agency before construction
  • agree each individual location with the Environment Agency
  • install tanks, liners and slurry bags to manufacturer’s instructions
  • make sure the base of earth bank lagoons is above the water table - there should be at least one metre of clay subsoil beneath the proposed base
  • use a trial pit to confirm the depth of the clay layer - the resulting hole must be backfilled and puddled in
  • use liners where there is doubt about soil permeability - lower grade liners should suffice for temporary storage but use high grade liners in high risk areas
  • monitor it to make sure there are no leaks
  • locate it at least 10 metres from watercourses and land drains - use temporary trial trenches if you are unsure about the presence of land drains
  • locate it at least 50 metres from groundwater sources
  • de-commission it as soon as it’s no longer needed

If you are using shared facilities you must:

  • consider any biosecurity risks
  • agree management arrangements
  • agree where responsibility lies

For more information about storing slurry see CIRIA: Livestock manure and silage storage infrastructure for agriculture.

How to spread slurry or milk

You must spread slurry or milk:

  • thinly and widely
  • at an application rate not exceeding 20 cubic metres per hectare - you must use a lower application rate if run-off could enter surface water

You must only spread slurry or milk on land with low run-off risk.

Low run-off risk land:

  • has an average slope of less than 3 degrees
  • does not have land drains other than sealed impermeable pipes
  • has not been pipe drained, mole drained or sub-soiled in the last 12 months
  • does not have a shallow soil less than 30cm above fissured rock
  • has a sufficient depth and suitable type of soil above groundwater to prevent pollution
  • is not within a designated groundwater source protection zone 1
  • is at least 50 metres from surface water or a conduit leading to surface water
  • is at least 50 metres from springs, wells and boreholes where groundwater is used for human consumption
  • does not have compacted soil or a soil surface which is capped - you can only spread where the soil is permeable and has a good structure
  • does not have cracked soil above a land drainage system or groundwater

If you mix slurry with milk you increase the risk of lethal or explosive gases such as methane, carbon dioxide, ammonia and hydrogen sulphide.

When the Environment Agency may not take enforcement action

When exceptional circumstances stop you being able to comply with legislation and guidance, spreading to land may be your only viable option. If you spread slurry and milk during exceptional circumstances without causing pollution, the Environment Agency may decide not to take enforcement action.

You must:

  • contact the Environment Agency before you spread any slurry or milk to land
  • agree with them that spreading is the only option available
  • only spread the amount of slurry and milk you need to reduce the risk of pollution
  • only spread up to 20 cubic metres per hectare and on the lowest risk land available - you may be able to export the slurry and milk to neighbouring farms
  • carry out regular checks before, during and after spreading to ensure there is no pollution taking place

You are still responsible for any pollution that you cause.

Contact the Environment Agency

General enquiries

National Customer Contact Centre
PO Box 544
S60 1BY


Telephone 03708 506 506

Telephone from outside the UK (Monday to Friday, 8am to 6pm GMT) +44 (0) 114 282 5312

Monday to Friday, 8am to 6pm.

The impact of COVID-19 means you may experience some delays in responses.

Call the environment incident hotline on 0800 80 70 60 out of hours or in an emergency.

Published 10 August 2018
Last updated 4 August 2022 + show all updates
  1. Removed the review date.

  2. We have reviewed this guidance and it still applies. We will review it again on 31 October 2021.

  3. We have updated this guidance so that it applies to exceptional circumstances, not just exceptional weather. We have also extended the review date to 31 October 2020.

  4. First published.