A driveway with an open manhole and traffic cones, featuring equipment for CCTV surveys, including a cable reel and monitor. This setup suggests maintenance work on blocked drains. A brick house entrance is visible in the background.

Drainage Installations in New Forest

– Smart Drainz –

A Guide to Retrofitting Non-Compliant Drainage Systems

With increasing scrutiny over wastewater discharge and environmental protection, many homeowners and property managers across the New Forest are discovering that their ageing drainage systems no longer meet current standards. Whether triggered by a failed percolation test, sale-related pre-purchase surveys, or enforcement from the Environment Agency, non-compliant systems present both legal and environmental liabilities.

Updating these systems requires a structured approach to testing, specification, and new drainage installations, all in accordance with the General Binding Rules, BS EN 12566/BS 6297, and—where required—valid Environmental Agency Discharge Permits. Achieving full compliance is not optional; it is a statutory obligation with real consequences for those who fall short.

Identifying Non-Compliant Drainage Systems

Non-compliant drainage systems are typically those installed before the introduction or revision of relevant legislation. Common examples include older septic tanks that discharge directly to a watercourse, or soakaway systems situated too close to buildings or boreholes. Many of these systems pre-date the 2015 revisions to the General Binding Rules, which now prohibit discharge to surface water from septic tanks and mandate stringent distance, construction, and maintenance criteria.

Key signs of non-compliance include:

Septic tank discharging to a ditch, stream, or river
Foul odours or visible effluent at ground level
No documented system specification or maintenance records
Soakaway failures or slow-draining foul appliances
Failed or undocumented percolation test results

For homeowners in the New Forest, these red flags are not uncommon due to the age of many rural properties and the sensitive status of surrounding catchments. Pre-purchase surveys in particular often bring these issues to light, prompting urgent remedial action.

A person holds an inspection camera near a round metal grate with parallel bars, likely checking for blocked drains. The camera's screen displays a blue and gray-toned image against the concrete surface, typical of a drainage contractor at work.

Legal Obligations Under the General Binding Rules

The General Binding Rules apply to small sewage discharges from septic tanks and package treatment plants in England. These rules, updated in 2020, stipulate that all discharges to ground must be via a drainage field designed and installed to BS 6297:2007. Discharges to surface water are only permitted from a package treatment plant, and only if effluent quality and distance requirements are met—or if a formal Environmental Agency Discharge Permit has been issued.

A system may breach the rules if:

The discharge method is no longer permitted (e.g., direct to surface water from a septic tank)
The discharge point is too close to a building, borehole, or boundary
There is pollution or nuisance caused by the system
The treatment plant fails to meet the required effluent standards

In such cases, property owners are legally required to upgrade or replace the system—typically within a defined enforcement timeframe.

From Survey to Specification: Retrofitting a System

Retrofitting is not simply about replacing components. It’s a process of design-led remediation that begins with site assessment and ends in certified compliance.

The steps in the retrofit process include:

A full drainage survey, including CCTV and invert level mapping
Soil testing, including a BS-compliant percolation test
Review of discharge routes, groundwater levels, and proximity constraints
Engineering design of the new drainage installation, suited to local soil conditions
Application for Environmental Agency Discharge Permits where required

A failed percolation test may prevent use of a conventional drainage field, requiring above-ground mounds, tertiary treatment solutions, or alternative discharge options. In the New Forest, where clay soils and high water tables are common, these outcomes are frequent and must be engineered around responsibly.

Close-up of a corroded metal pipe interior, typical in drain re-lining projects. The rough, rust-covered walls create a textured appearance, while the dark, narrow passage fades to black towards the center, emphasizing depth.

Engineering a Compliant Solution

Modern drainage installations must meet stringent design and performance standards. This includes not only the structural integrity of the components but their environmental impact and future maintainability. In some cases, a packaged treatment plant discharging to ground may be the only viable option. In others, connection to mains drainage (if accessible) may be mandated by the planning authority.

Key engineering considerations include:

Sizing systems to actual daily flow, not historical estimates
Ensuring separation distances to avoid pollution or structural interference
Designing for long-term maintenance and desludging access
Verifying that system outflows remain within the scope of the General Binding Rules

Smart Drainz designs systems that meet all BS and Environment Agency requirements, and ensures that clients in the New Forest have a future-proofed drainage solution that stands up to environmental scrutiny and legal challenge.

When Are Permits Required?

Not all systems fall within the General Binding Rules. Where effluent volumes exceed 2m³/day, or discharges enter sensitive watercourses or groundwater protection zones, a formal Environmental Agency Discharge Permit is required. This includes detailed evidence of performance, site layout, system design, and predicted environmental impact.

Discharge Permits are likely to be needed when:

Discharge is to a ditch, stream, or river
Soils fail the percolation test, necessitating discharge to surface water
The site lies within a designated protection zone or floodplain
Volumes exceed thresholds for daily discharge

Pre-purchase surveys that identify such conditions can help future owners understand the real cost of upgrade or replacement and plan accordingly.

Futureproofing Through Retrofitting

Retrofitting is not just about meeting minimum standards. It is about delivering robust, long-term wastewater solutions that provide environmental protection, legal security, and peace of mind. In the New Forest, this often means tailoring the system to challenging terrain, high water tables, and ecological sensitivity.

Benefits of full retrofit and legal compliance:

Avoids Environment Agency fines and enforcement
Enhances property saleability and value
Reduces long-term maintenance and desludging issues
Guarantees safe, sanitary discharge

Whether prompted by system failure, planning enforcement, or property transfer, retrofitting with Smart Drainz ensures you are fully compliant and technically sound from day one.

Several orange PVC drainage pipes and connectors are placed next to a freshly dug trench in a grassy area, indicating ongoing work by a drainage contractor. This setup suggests plumbing or sewer improvements, potentially involving soakaways or sewage treatment plants.

Contact Smart Drainz

If you suspect your existing system is no longer compliant—or are planning to buy a property in the New Forest—contact Smart Drainz for technical assessments, pre-purchase surveys, compliant drainage installations, and certified percolation test results. Call us today on 07950 753233 to arrange a site survey and start your retrofit journey.