Thinking of installing a septic tank or sewage treatment plant? Whether you’re building your dream home in the countryside or developing a group of rural properties, off-mains drainage is often the only option. But before a single trench is dug, it’s crucial to understand one key step: applying for the correct permits.
Failure to comply with the latest Environment Agency regulations could result in legal action, environmental damage, or costly delays to your project. In this guide, we’ll walk you through when you need a septic tank permit, how to apply, and what steps to take for a compliant, future-proof drainage system.
What Is a Septic Tank and When Is It Used?
A septic tank is a private wastewater treatment system designed for properties that aren’t connected to the public sewer network. They’re commonly used in rural areas and self-build plots, where connection to mains drainage is impractical or cost-prohibitive.
There are two main types of off-mains systems: septic tanks, which provide primary treatment before releasing effluent into a drainage field, and packaged sewage treatment plants, which treat waste to a higher standard, often allowing discharge directly to surface water (such as streams or ditches).
These systems are frequently installed for individual rural homes, new build properties on remote plots, small housing developments, and farm conversions or annexes.
Do You Need a Permit for Your Septic Tank or Treatment Plant?
In many domestic cases, the Environment Agency allows the discharge from small treatment systems without the need for a permit, as long as strict General Binding Rules (GBRs) are followed.
However, you will need a permit if any of the following apply: your discharge is to ground (such as a soakaway or drainage field) in a sensitive location—e.g. within a Source Protection Zone (SPZ1) or near a designated nature site; your discharge is to surface water (e.g. a stream or ditch), but your system does not meet the required treatment standards; your daily discharge volume exceeds 2,000 litres/day to ground (typically more than one domestic property) or 5,000 litres/day to surface water; the system is non-standard, experimental, or uses unapproved technology; or you cannot meet one or more of the General Binding Rules (e.g. unsuitable discharge point).
Always check if your site is within a sensitive groundwater or environmental area using the Environment Agency’s online mapping tool. You can also read useful info in our related guide, covering installation of new sewer connections.
Who Issues Septic Tank Permits and Why?
In England, septic tank permits are issued by the Environment Agency. Their role is to ensure wastewater discharges don’t pose a risk to public health or pollute watercourses, soil, or groundwater.
In other parts of the UK, the relevant environmental bodies are: Natural Resources Wales (NRW), Scottish Environment Protection Agency (SEPA), and Northern Ireland Environment Agency (NIEA).
Permits are issued based on the location of the discharge, the system type and discharge method, volume and frequency of discharge, and proximity to boreholes, rivers, wetlands or conservation areas.
How to Apply for a Septic Tank Permit: Step-by-Step
Applying for an environmental permit may sound daunting, but the process is straightforward if you follow these steps:
- Assess your site – Identify where the discharge will go (ground or surface water) and check for sensitive areas nearby.
- Calculate daily discharge volume – Based on property occupancy or flow rates.
- Choose the right system – It must be UKCA/CE marked and meet BS EN standards.
- Design the installation – Include percolation test results, drainage field layout and maintenance plans.
- Apply online – Submit your application via GOV.UK with supporting documents.
- Wait for approval – The process can take several weeks. Avoid installation until you have written confirmation.
A professional installer or drainage consultant can help ensure all paperwork, mapping, and flow calculations are correct from the outset.
Planning Permission and Building Regulations
It’s important to note that an environmental permit is not a substitute for planning permission or Building Regulations compliance.
You may also need planning permission for the installation of the drainage system (especially on new builds or developments) and Building Regulations approval, under Part H, which governs drainage and waste disposal.
It’s good practice to consult with Building Control or an Approved Inspector early in your project to avoid delays or compliance issues down the line.
Septic Tanks for Developments or Shared Systems
If your system will serve multiple dwellings or a commercial site, the rules become more stringent.
In these cases, you’ll almost certainly need a bespoke environmental permit due to higher discharge volumes, shared responsibility between occupants, and potential impact on nearby watercourses or land.
Developers should work with drainage designers and approved installers to create a scalable, maintainable system—and to manage the permit application on behalf of the project.
What Happens If You Don’t Get a Permit?
Discharging without a required permit is a criminal offence and can result in enforcement action by the Environment Agency, fines or prosecution under the Environmental Permitting Regulations, planning refusals or delays on property sales, pollution of nearby watercourses or private wells, and future costs for remediation or upgrading the system.
This is particularly relevant during conveyancing—properties with unpermitted septic tanks can face legal complications and reduced sale value.
Common Pitfalls to Avoid
Here are a few mistakes we frequently see: assuming no permit is needed for a rural site, discharging to a ditch without Environment Agency approval, installing a non-compliant or undersized system, failing to carry out a percolation test, or missing out the maintenance plan in the application.
Avoid these issues by engaging a qualified installer like Tiger Utilities early in the process.
Final Thoughts: Get Your Drainage Right from Day One
Whether you’re a homeowner, self-builder, or developer, proper planning of your off-mains drainage system is essential. Don’t leave permitting as an afterthought—it’s a legal requirement that protects both the environment and your investment.
By understanding the rules, choosing the right system, and applying for the necessary permit, you can avoid costly setbacks and ensure full compliance with environmental law.
Need Help with a Septic Tank Permit?
Tiger Utilities can take the hassle out of your application. From system design and site surveys to Environment Agency paperwork and full installation—we handle it all.
Domestic and multi-unit systems
WIAPS-approved engineers
Fully compliant with EA, Building Regs & Planning
Contact us today to get started on a safe, efficient, and compliant drainage solution for your project.
