Store slurry, silage and fuel oil safely on your farm

The Silage, Slurry and Agricultural Fuel Oil (SSAFO) Regulations, in force since 6 April 2010, set how you must build and keep stores of these materials to protect water. They apply in England to whoever has custody or control of the material on a farm.

Rules for every new or substantially changed store

The construction rules apply to a new store and to one you substantially change. You may need a larger safety zone than the standard distance from water, for example near a water supply intake. A substantial change usually means structural alteration, such as increasing capacity or relocating the store, rather than a minor repair. If you are not sure whether your work counts, ask the Environment Agency.

Slurry stores

Slurry is liquid or semi-liquid livestock excreta, with bedding, rainwater and washings, that can be pumped or run by gravity.

Silage stores

A silo must have an impermeable base that extends beyond its walls, with channels around the edge draining into an effluent tank. The base must be designed to BS 8007:1987 for concrete, or built from hot-rolled asphalt to BS 5502 Part 21, and be resistant to attack by silage effluent. Retaining walls must withstand the wall loadings in BS 5502 Part 22. The effluent tank needs at least this capacity:

Never put silage effluent into an under-floor slurry store. Mixing them can give off gases that are lethal to people and livestock.

Bales need no specially built base if you seal them in an impermeable membrane or bag, make sure nothing can leak into water, and keep them at least 10 metres from inland freshwaters and coastal waters. It is an offence to open or unwrap a bale within 10 metres of water. Field silage, which is made or stored on open land with no walls or earth banks and without disturbing the topsoil, must be at least 10 metres from water and at least 50 metres from a protected water supply source. Silage kept temporarily in a container or trailer for transport is outside the rules.

Agricultural fuel oil stores

Tell the Environment Agency before you build

Notify the Environment Agency at least 14 days before you build new storage, substantially change an existing store or first use a new site for field silage. The regulations set 14 days before first use as the legal minimum, while GOV.UK asks for 14 days before construction starts so the Environment Agency can advise before you commit to a design. Notify online, saying the type of store and its location. You can add site plans, design drawings, manufacturer specifications for prefabricated stores and, for earth-banked stores, soil tests. Check too whether the store needs planning permission.

Stores you already have

A silo, slurry system or fuel tank that was in use or built before 1 March 1991, or whose construction contract was entered into before that date and finished before 1 September 1991, is exempt from the construction rules. The exemption ends if you make a substantial change, and it ends too if you do not comply with an Environment Agency notice.

What happens if you break the rules