Keep a new driveway, parking area or path off the drainage field entirely: Approved Document H says no access roads, driveways or paved areas should be located within the disposal area. Rainwater from the new surface needs its own route, such as a permeable surface or a separate soakaway sited well away from the field, and must never be sent into the septic tank, treatment plant or drainage field.
When this guide fits
Clues worth recording
- You are planning a driveway, parking area or hardstanding on an off-mains property
- Nobody is sure exactly where the drainage field runs
- The new surface will need a soakaway or drain
- The tanker needs to reach the tank across the new surface
What is the difference between a drainage field and a soakaway?
A drainage field is a network of perforated pipes that spreads settled effluent from a septic tank, or treated effluent from a package plant, through suitable soil, where further treatment happens. It is part of the sewage system. A soakaway is a pit or trench that lets clean rainwater from roofs and paved areas soak into the ground.
England’s general binding rules for discharges to ground treat them differently: a sewage discharge through a soakaway designed for rainwater cannot meet the rules if that soakaway was installed after December 2007. The effluent needs a drainage field built to the British Standard, BS 6297, or an environmental permit.
Related guide: drainage field failure: symptoms and options
Where must a driveway not go?
Approved Document H, the building regulations guidance on drainage in England, says a drainage field or mound should be at least 15 metres from any building, at least 10 metres from any watercourse or permeable drain, and at least 50 metres from the point of abstraction of any groundwater supply. It also says that no access roads, driveways or paved areas should be located within the disposal area, and that no water supply pipes or other underground services should run through it, other than those the system itself needs.
Before any digging, find out where the tank, the outlet pipe and the whole field are. Old plans, the seller’s information pack and a tracing survey can help. Machinery driving across the field during construction can damage the pipes and compact the soil, so mark the area off before work starts.
Where should the driveway’s rainwater go?
The building regulations set an order of priority for rainwater from roofs and paved areas: first an adequate soakaway or other infiltration system; where that is not reasonably practicable, a watercourse; and only then a sewer. On an off-mains property there is often no surface-water sewer, so infiltration is usually the first option.
GOV.UK guidance on the permeable surfacing of front gardens explains that a permeable driveway lets water soak through the surface and a free-draining sub-base into the ground, and that the soil below must be sandy or gravelly rather than clay; on clay, a connection to a drain may be needed. If a soakaway is used, Approved Document H says it should not be built within 5 metres of a building or road, where the water table reaches its base at any time of year, or so close to a drainage field that the overall soakage capacity of the ground is exceeded or the field is impaired.
Better Driveways explains when a new driveway needs planning permission and what counts as permeable
Never connect driveway drains, roof downpipes or a soakaway overflow to the septic tank, treatment plant or drainage field. Clean surface water can hydraulically overload the system.
Do I need planning permission for the driveway?
For a house in England, the Planning Portal says you do not need planning permission for a new or replacement driveway of any size if it uses permeable surfacing, such as gravel, permeable concrete block paving or porous asphalt, or if the rainwater is directed to a lawn or border to drain naturally. Covering more than five square metres of a front garden with a traditional impermeable surface that does not let water run to a permeable area needs permission. Listed buildings, conservation areas and Article 4 directions can change this, so check with the council if any could apply.
Planning permission for the driveway is separate from the rules for the sewage system. If the driveway work means moving or changing the septic tank, treatment plant or drainage field, building regulations approval and the environmental rules for a new discharge may also apply.
Keep access for the tanker
A septic tank or treatment plant needs regular desludging, and England’s general binding rules say sludge must be removed before it exceeds the system’s capacity, at least once a year or as the manufacturer instructs. Plan the driveway so the tanker can get close enough to the tank cover without crossing the drainage field. A new surface that cannot take the weight of the vehicle, or a gate that is too narrow, can turn routine emptying into a problem.
Related guide: how often a septic tank should be emptied
Planning new surfaces close to the house? Better Driveways compares gravel, block paving and other driveway materials
What if the field has to move?
Sometimes the only sensible place for a driveway is where the field already is. Moving the field is a bigger job than it sounds. Under England’s general binding rules, moving the discharge point more than 10 metres makes it a new discharge, and new discharges have extra rules, including connecting to a public foul sewer where the Environment Agency decides that is reasonable. Approved Document H expects a percolation test and a trial hole before a new drainage field is designed.
Related guide: planning a new off-mains drainage system
Questions homeowners ask
What people usually want to know
Can I park on my drainage field?
It is best not to. Approved Document H says no access roads, driveways or paved areas should be located within the disposal area, and vehicles can crush pipes and compact the soil.
Can driveway rainwater go into my septic tank?
No. Clean rainwater should have its own route, such as a permeable surface or a separate soakaway. Sending it into the foul system can overload the tank and the drainage field.
How far should a soakaway be from my drainage field?
Approved Document H does not give a single distance. It says soakaways should be sited far enough from any drainage field that the ground’s overall soakage capacity is not exceeded and the field still works. A designer should check this against the soil and percolation test results.
Can an old rainwater soakaway take my septic tank effluent?
Not in England if the soakaway was installed after December 2007. The general binding rules say the effluent needs a drainage field built to BS 6297, or a permit.
Sources & review
Evidence behind this guide
Reviewed 2 October 2026. We use primary guidance where available and label trade-body advice clearly.