In England and Wales, discharging effluent to surface water or groundwater is regulated under the Environmental Permitting (England and Wales) Regulations 2016. Depending on the activity and risk, you need a bespoke permit, can register for standard rules, or may qualify for an exemption. Discharges to the public sewer are governed separately, by trade effluent consent.

What is environmental permitting under EPR 2016?

The Environmental Permitting (England and Wales) Regulations 2016 (EPR 2016, SI 2016/1154) consolidate most pollution-control regimes into a single permitting framework administered, for water discharges, by the Environment Agency in England and by Natural Resources Wales in Wales. Two regulated activities matter most for effluent producers:

  • Water discharge activity — discharging or allowing to enter inland freshwaters, coastal waters or relevant territorial waters any poisonous, noxious or polluting matter, waste matter, or trade or sewage effluent.
  • Groundwater activity — the discharge of a pollutant that results, directly or indirectly, in an input to groundwater (for example soakaways, infiltration systems or land treatment).

EPR 2016 replaced the old discharge-consent system under the Water Resources Act 1991. It works on a tiered, risk-based principle: the greater the environmental risk, the more bespoke and heavily conditioned the authorisation. Note that Scotland (CAR regime, SEPA) and Northern Ireland operate separately. For an overview of the numeric limits that permits enforce, see our guide to UK effluent discharge compliance and the sibling article on effluent discharge standards in the UK.

Bespoke permit, standard rules or exemption — which applies?

EPR 2016 offers three tiers of authorisation. Choosing the right one is the first decision, and getting it wrong is itself an offence — an unpermitted discharge is a strict-liability breach.

TierWhat it isWhen it applies
Exemption / exclusionLow-risk activity registered (or excluded) without a full permitSmall, clean discharges meeting tightly defined conditions — e.g. certain domestic or very low-volume flows within set limits
Standard rules permitRegister against a fixed, pre-set rule set published by the regulatorCommon, well-understood discharges (e.g. treated sewage below a threshold, some site drainage) where your activity fits the published envelope exactly
Bespoke permitIndividually written conditions and emission limits for your siteHigher-risk, higher-volume, complex or sensitive-location discharges — most industrial trade effluent to a watercourse
Key regulatory rule — no discharge without authorisation. Under EPR 2016 it is an offence to operate a regulated facility, or cause or knowingly permit a water discharge or groundwater activity, except under and to the extent authorised by an environmental permit. Liability for the base offence does not require proof of intent or negligence — it is strict. 'I did not know a permit was needed' is not a defence.

How are emission limit values set?

For a bespoke permit the Environment Agency derives numeric emission limit values (ELVs) from two directions and applies the more stringent.

  1. Best Available Techniques (BAT). What is achievable using the best available treatment technology that is technically and economically viable for the sector. For installations this draws on published BAT Conclusions / BREF reference documents.
  2. Receiving-water standards. The discharge must not cause the receiving water to breach its Environmental Quality Standards and Water Framework Directive (WFD) status objectives. This is assessed by a mass-balance / mixing calculation.
Governing principle — the mass-balance (mixing) check. A simplified conservative mixing model estimates the downstream concentration:
Cds = (Qr·Cr + Qe·Ce) / (Qr + Qe)
where Cds = downstream concentration, Qr = river flow (often the low-flow Q95), Cr = upstream background concentration, Qe = effluent flow and Ce = effluent concentration. The permit limit Ce is set so Cds stays within the EQS at the design low flow. Worked example: river Q95 = 200 L/s, background ammonia Cr = 0.2 mg/L, EQS for Cds = 0.6 mg/L; effluent Qe = 20 L/s. Solving for the allowable Ce: 0.6 = (200·0.2 + 20·Ce)/220 → 132 = 40 + 20·Ce → Ce = 4.6 mg/L ammonia. If BAT for that sector achieves ~3 mg/L, the tighter BAT figure would govern.

Because low river flow gives the least dilution, ELVs are habitually set against Q95 — the flow exceeded 95% of the time — so the water is protected in dry conditions, not just on average.

What monitoring, MCERTS and competence are required?

A permit is only as good as the evidence that you comply with it. Bespoke permits impose self-monitoring obligations — sampling frequency, determinands, flow measurement and reporting — proportionate to the risk.

  • MCERTS. Where the permit requires it, monitoring must meet the Environment Agency's Monitoring Certification Scheme (MCERTS): certified instruments, MCERTS-accredited laboratories (to ISO/IEC 17025) for sample analysis, and inspected flow-measurement systems. This gives the data legal standing.
  • Operator competence. The operator must be able to manage the activity so as to comply — a suitable management system, competent technical staff, and no relevant convictions that would make them unfit.
  • Record-keeping and reporting. Retain results (commonly for a set period) and report to the regulator on the specified schedule, including notifying breaches promptly.

Compliance is typically judged against limits expressed as an absolute (never-exceed) value and/or a percentile — for instance a 95-percentile concentration — so occasional excursions are assessed against the permitted statistical basis rather than a single reading.

How is the permit obtained and enforced?

The application route (see the step-by-step below) runs from optional pre-application through submission, public consultation for bespoke permits, to determination, when the regulator grants (with conditions), refuses, or requests more information. Once granted, the permit is a live legal instrument that can be varied, transferred or surrendered.

Enforcement under EPR 2016 is graduated, using the regulator's Enforcement and Sanctions Policy:

  • Notices — enforcement, suspension or revocation notices requiring action or halting the activity.
  • Civil sanctions — compliance notices, restoration notices, variable monetary penalties, and enforcement undertakings (a legally binding offer to put things right and contribute to environmental improvement).
  • Prosecution — for serious or persistent offences, carrying unlimited fines in the Crown Court and, for certain offences, imprisonment. Sentencing follows the Environmental Offences Definitive Guideline, which scales fines to culpability, harm and turnover.

Regulatory detail changes. The framework above is accurate at the time of writing, but charges, standard rule sets and guidance are updated regularly — always verify the current position on GOV.UK before you act, or take advice on your site-specific permitting strategy.

Common permitting mistakes

  • Choosing the wrong regime. Assuming a sewer discharge needs an EPR permit (it needs a consent), or vice versa. Follow the receiving body.
  • Discharging while an application is pending. Submitting an application does not authorise the activity — the discharge remains unlawful until the permit is granted.
  • Under-scoping determinands. Failing to declare a pollutant the receiving water is sensitive to, leading to a variation, tighter limits or enforcement later.
  • Non-MCERTS monitoring. Using data that has no legal standing when it is needed to demonstrate compliance.
  • Ignoring low-flow conditions. Sizing treatment for average dilution, then breaching the EQS in a dry summer at Q95.

How to apply for an environmental permit for a water discharge

  1. Screen the activity and pick the tier. Confirm it is a water discharge or groundwater activity and whether it qualifies for an exemption, fits published standard rules, or needs a bespoke permit. Establish the receiving body to rule EPR in or out versus a sewer consent.
  2. Pre-application engagement. For bespoke or sensitive cases, use the Environment Agency pre-application service to agree scope, monitoring points and the impact assessment expected, reducing the risk of a stalled determination.
  3. Characterise the effluent and receiving water. Compile flow (average and peak), determinand concentrations, and the receiving-water data (Q95, background quality, EQS/WFD status) needed for the mass-balance assessment.
  4. Prepare and submit the application. Complete the relevant application forms, supporting assessments and management-system evidence, demonstrate operator competence, and pay the application charge to the regulator.
  5. Consultation and determination. For bespoke permits the application is publicly advertised and consulted on. Respond to any requests for information. The regulator then grants (with conditions), refuses, or issues a draft for comment.
  6. Operate, monitor and report. On grant, implement the permit: MCERTS-compliant monitoring, record-keeping, breach notification and periodic reporting. Apply to vary the permit before any change that would affect the conditions.

Frequently asked questions

Do I need an environmental permit to discharge to a river?

Yes. In England and Wales, discharging trade or sewage effluent to a river, estuary, coastal water or groundwater is a regulated activity under EPR 2016 and requires an environmental permit, or a registered exemption for very low-risk cases. Discharging without the correct authorisation is a strict-liability offence, regardless of intent.

What is the difference between an EPR permit and trade effluent consent?

An EPR permit, from the Environment Agency, covers discharges to surface water or groundwater and is driven by receiving-water quality and BAT. A trade effluent consent, from your water and sewerage company under the Water Industry Act 1991 s.118, covers discharges to the public sewer. The regime depends on where the effluent goes, not what it contains.

When can I use standard rules instead of a bespoke permit?

Standard rules apply when your discharge fits exactly within a published rule set the regulator has written for common, well-understood, lower-risk activities. If your activity is higher-risk, higher-volume, in a sensitive location, or falls outside the published envelope in any respect, you need a bespoke permit with individually tailored conditions and limits.

How does the Environment Agency set my permit limits?

The regulator derives emission limit values two ways and applies the tighter. First, Best Available Techniques set what is technically and economically achievable for your sector. Second, a mass-balance calculation ensures the discharge does not push the receiving water beyond its Environmental Quality Standards and Water Framework Directive objectives, usually assessed at low river flow (Q95).

What is MCERTS and do I need it?

MCERTS is the Environment Agency's Monitoring Certification Scheme, covering certified instruments, accredited laboratories and inspected flow measurement. Where your permit requires MCERTS-standard monitoring, using it gives your compliance data legal standing. Check your specific permit conditions, since the required standard depends on the risk and the determinands being monitored.

What happens if I breach my permit?

Enforcement under EPR 2016 is graduated. Minor issues may attract advice, notices or civil sanctions such as compliance notices, variable monetary penalties or enforcement undertakings. Serious or persistent breaches can lead to prosecution, with unlimited fines in the Crown Court and, for some offences, imprisonment. Prompt self-reporting and cooperation generally reduce the sanction.

Sources & further reading