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.
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.
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.
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 03332 027129 to arrange a site survey and start your retrofit journey.