Frequently asked questions

See the answer in the Servicing section above. In short, yes – but only a competent, British Water-accredited technician can lawfully carry out the work.

Yes. WCI works with several UKAS-accredited laboratories. Our service engineers can collect effluent samples and arrange for laboratory analysis to demonstrate that your system is meeting the conditions of its Environment Agency permit.

Yes. Under Building Regulations, a trial hole must be excavated alongside the percolation test to determine the depth of the seasonal groundwater table. This information is required to ensure any drainage field designed and installed at your property meets Building Regulations and the relevant British Standards.

A percolation test determines how quickly water drains through the soil on your land. This data is required to calculate whether a British Standard drainage field can be adequately designed and installed at your property. If the soil drains too slowly (common in heavy clay soils) or too quickly (common in sandy soils), a conventional drainage field may not be viable. A percolation test will confirm what options are available to you.

WCI can carry out a compliance survey and issue a formal report confirming whether your system meets the General Binding Rules or the conditions of its Environment Agency permit. Where defects or non-compliances are identified, the report will include a costed plan for repair or replacement. This survey is frequently requested during property sales and conveyancing.

Foul odours from a private drainage system are usually caused by one of the following: an underperforming system; poor ventilation of the drainage pipework; a dry water trap (flush your toilets and run your taps to refill them); a broken pipe or seal; or a failed air admittance valve. WCI can carry out a smell investigation using dye, CCTV and smoke testing to identify the source of the odour and recommend a remediation plan.

Yes. Contact us with details of what has been installed and we will provide a quote for commissioning and ongoing servicing.

Some systems – including the GRAF Solido range – have a holiday mode setting that can reduce energy consumption during absences of up to four weeks. If you plan to be away for longer, consider having the system emptied before you leave and switching it off to prevent the bacterial colony from dying or the contents from freezing. Not all systems have a holiday mode, so check with us if you are unsure.

It depends on the make and model. Some systems have a blower that runs continuously; others operate intermittently. If you are unsure whether your system is behaving as it should, call us and we can advise. Pumps that move water to a higher level should only activate when the water level inside the tank rises high enough to trigger them – a pump running all the time is usually a sign of a problem.

For domestic systems, typically every one to three years, though the exact frequency depends on the size of the system, the number of occupants and how well the system is maintained. Commercial systems may need emptying every two to six months. When WCI services your system, we will take a sludge reading and advise you on whether emptying is required.

The rule is simple: only the three Ps – pee, paper and poo. Everything else should go in the bin. Wet wipes, sanitary products, cotton buds, nappies and cooking fats should never enter the foul drainage system. When choosing cleaning products, opt for low-phosphate or phosphate-free formulations, use them sparingly, and spread laundry washing throughout the week rather than doing multiple loads in a single day. Wipe greasy or oily pans with kitchen roll and bin it before washing – this prevents fats from entering and clogging the system.

These two components are often confused. A blower (also called a compressor or aerator) is usually housed in a green kiosk above ground. It runs continuously, pumping air down into the sewage treatment plant to feed the aerobic bacteria that break down sewage. You will hear it as a low hum or buzz.

A pump is almost always located inside the tank, submerged in the water. Its job is to move treated water from one part of the system to another when gravity cannot do the work – for example, lifting clean effluent up to a discharge point on higher ground. Most pumped systems include a high-level alarm that will sound or flash if the pump fails. Unlike the blower, a pump should only run intermittently; a pump running continuously is using unnecessary electricity and will wear out prematurely.

Commercial systems may also include irrigation pumps, sludge return pumps and more. If you are unsure what is installed at your property, let us know when you book your first service and our engineers will identify everything during the visit.

The Environment Agency’s General Binding Rules state that a sewage treatment plant must be serviced and maintained by a competent person. This means technicians who have completed the British Water Accredited Service Technician training. All WCI Service Engineers are fully trained in-house and accredited by British Water. A list of accredited service providers is available at britishwater.co.uk.

A standard domestic system is typically serviced in around one hour on site. Commercial units generally take a couple of hours, though this can increase where the system requires a two-person team, confined-space entry, complex controls or multiple heavy lids. Any additional time requirements will be identified in our free pre-service inspection and factored into the quote.

The total cost of a service is labour plus materials plus VAT. Labour starts from £130 + VAT and varies depending on the distance from our office. Material costs vary from system to system – if you can provide the make and model of your air blower (for example, a JDK 100), we can give you a fixed cost for the service before we attend.

A full service report is issued after every visit. Checks carried out include:

Health and safety – including structural integrity of the tank and access covers.
Air blower operation – including inspection and replacement of diaphragms, carbon vanes, pistons and filters as required.

Electrical checks – including control panels, air blowers, submersible pumps, alarms and beacons.
On-site effluent testing – to check the quality of water being discharged. Tests can include pH, dissolved oxygen, ammonia, phosphate and temperature.

Laboratory analysis – where required, WCI can collect samples for testing at a UKAS-accredited laboratory to demonstrate compliance with the General Binding Rules or an Environment Agency permit.

Most manufacturers recommend that domestic package sewage treatment plants are serviced annually. During a service, the engineer will assess – among other things – sludge levels within the tank and will advise whether the system needs emptying. Commercial systems require a bespoke servicing regime and may need attention anywhere from once a month to every six months, depending on the size, complexity and required treatment quality of the system.

Yes. We have a service engineer on call every day of the year. Call 01984 623 404 and your call will be directed to the engineer on duty. Please leave a message if they cannot answer immediately – they will call you back as soon as possible. When you call, have the following to hand: your name and full site address, details of your system (make, model and age if known), and a description of the problem – for example, whether an alarm is sounding, water is backing up, or the blower is making unusual noises. Photos of the system, a note of the water level in the tank, or a short audio recording of any unusual sounds can also be very helpful.

For domestic sewage treatment plants, pumping stations and rainwater harvesting systems, we typically cover Somerset, Devon, Dorset and Wiltshire. For commercial systems we operate nationwide, from North Wales to the South Coast and Cornwall. If you are just outside these areas, call us – we may still be able to help.

We service all makes and models of sewage treatment plant, pumping station and rainwater harvesting system. Manufacturers we regularly work with include GRAF, Marsh, Biodigester, WSc (formerly WPL/WCS), Premiertech Aqua, Klargester, Tricel, HABA, Entec, Acorn, Biorock, Titan, August, KEE, Harlequin, Xylem and TT Pumps – plus the occasional rare plant whose origins are unknown. If you are unsure whether we can service your system, just give us a call.

See the answer in the Servicing section above. In short, yes – but only a competent, British Water-accredited technician can lawfully carry out the work.

Yes. WCI works with several UKAS-accredited laboratories. Our service engineers can collect effluent samples and arrange for laboratory analysis to demonstrate that your system is meeting the conditions of its Environment Agency permit.

Yes. Under Building Regulations, a trial hole must be excavated alongside the percolation test to determine the depth of the seasonal groundwater table. This information is required to ensure any drainage field designed and installed at your property meets Building Regulations and the relevant British Standards.

A percolation test determines how quickly water drains through the soil on your land. This data is required to calculate whether a British Standard drainage field can be adequately designed and installed at your property. If the soil drains too slowly (common in heavy clay soils) or too quickly (common in sandy soils), a conventional drainage field may not be viable. A percolation test will confirm what options are available to you.

WCI can carry out a compliance survey and issue a formal report confirming whether your system meets the General Binding Rules or the conditions of its Environment Agency permit. Where defects or non-compliances are identified, the report will include a costed plan for repair or replacement. This survey is frequently requested during property sales and conveyancing.

Foul odours from a private drainage system are usually caused by one of the following: an underperforming system; poor ventilation of the drainage pipework; a dry water trap (flush your toilets and run your taps to refill them); a broken pipe or seal; or a failed air admittance valve. WCI can carry out a smell investigation using dye, CCTV and smoke testing to identify the source of the odour and recommend a remediation plan.

In our experience, the five most common compliance failures are:

A septic tank discharging directly into a ditch, watercourse or highway drain. Septic tanks must discharge to the ground via a drainage field.

A system that has failed due to a lack of maintenance – for example, a blocked or collapsed drainage field, damaged tankage, or ingress of rainwater into the system.

A tank that is significantly undersized for the current property, typically where bedrooms have been added without the foul drainage system being upgraded accordingly.

A system that requires a permit – for example, where discharge exceeds 2m³ per day to the ground, or the drainage field is within 50 metres of a private drinking water supply.

A system where the old septic tank has been replaced by a package sewage treatment plant, but the effluent was directed into plastic rainwater crates rather than a properly designed drainage field or watercourse – which is not a legal discharge point.

Yes – in principle. If you are purchasing a property without a mortgage, or you can satisfy your lender that the system will be brought into compliance within 12 months (the Environment Agency’s standard requirement), a sale can proceed. However, in practice, lenders will often refuse to lend on a property with a confirmed non-compliant system. If the sale does go ahead, the obligation to bring the system into compliance passes to you as the new owner. Most buyers in this situation negotiate a reduction on the purchase price to offset the cost of replacement. If you are involved in buying or selling a property with a private drainage system, contact us early – a compliance survey and a clear remediation plan can prevent delays and abortive costs.

Under Section 23 of the Land Drainage Act 1991, consent is required before piping, culverting or obstructing a watercourse – whether permanently or temporarily. This can include installing new headwalls or outfall pipes, and in some cases may apply to repairs and maintenance works.

Who you need consent from depends on the location and classification of the watercourse:

If the watercourse is a Main River, you will need Flood Defence Consent from the Environment Agency.

If the watercourse is within a Drainage Board area (for example, the Axe Brue, Parrett or North Somerset Levels in Somerset), consent must be obtained from the relevant Drainage Board. Note that any activity within 9 metres of a watercourse in these areas requires Drainage Board consent.

If the watercourse is an ordinary watercourse outside a Drainage Board area and is not a Main River, consent must be granted by the local council.

WCI can advise on the correct consenting route for your project and assist with applications.

No – not directly. However, where the only available discharge point is a watercourse that happens to flow through a pond, it may sometimes be possible to demonstrate to the Environment Agency that the treated water is carried through the pond quickly and does not stagnate. This is a technically complex argument and can be difficult to make successfully. Where possible, discharging directly into a watercourse leaving a pond is always preferable and will be the Environment Agency’s expectation. Contact us to discuss your specific site situation.

You are the legal operator of a private drainage system if you own the property that uses it – including where the system is shared with another property – or if your property deeds or tenancy agreement state that you are responsible for maintaining it.

Under the General Binding Rules, if a property is sold, the outgoing operator must provide the new operator with a written notice stating that a small sewage discharge is being carried out, along with a description of the wastewater system and its maintenance requirements. You are not legally required to prove compliance at the point of sale, though questions about compliance are increasingly common during conveyancing – often late in the process, which can cause delays. If you are selling a property with a private drainage system, we strongly recommend commissioning a compliance survey in advance so you can answer any questions promptly and with confidence.

Processing times vary considerably. Minor variations and simple domestic bespoke permit applications typically take four months. Complex bespoke and standard rules permits can take eight to twelve months. It is important to factor these timescales into your project programme and not to proceed with installation before the permit is in place where one is required.

Yes. WCI prepares, submits and secures tens of Environment Agency permits each year, covering both standard and bespoke applications. Whether we are installing a system for you or you simply need help with the paperwork, call us and ask for our permitting team.

There are several circumstances in which a permit is required rather than relying on the General Binding Rules. Common examples include:

Discharging into a seasonally dry watercourse.

A private borehole within 50 metres of your septic tank drainage field.

Discharging more than 2m³ per day to the ground or more than 5m³ per day to a watercourse.

A drainage field that does not meet the relevant British Standard.

A system that includes a reed bed or discharges via a septic tank to a watercourse.

A system within a specified distance of a SSSI, SAC or SPA.

Sewage that is not classified as domestic.

If you are unsure whether you need a permit, contact us. We will assess your situation and advise – and can submit the application on your behalf if required.

The General Binding Rules were introduced by the Environment Agency in January 2015 to simplify the regulation of small sewage discharges from septic tanks and sewage treatment plants in England. There are 23 rules in total, and which ones apply to your system depends on when it was installed and where it discharges – whether to the ground or to a watercourse. If your system cannot comply with the applicable rules, you will need to apply for a permit. Full details are available on GOV.UK:

Discharge to the ground: gov.uk/guidance/general-binding-rules-small-sewage-discharge-to-the-ground

Discharge to a watercourse: gov.uk/guidance/general-binding-rules-small-sewage-discharge-to-a-surface-water

No. A correctly installed septic tank that meets either the Environment Agency’s General Binding Rules or the conditions of any permit that applies to it is entirely legal. The key requirement is that a septic tank must discharge into a drainage field or an appropriate soakaway – it cannot legally discharge directly into a ditch, watercourse or highway drain.

Yes. For clients who do not need a full turnkey installation, WCI can undertake a site walkover, advise on any required soil testing, interpret the results, apply for an Environment Agency permit (where required), specify the system to be installed, and commission the system once you or your groundworker have installed it. We can do as much or as little as your project requires. Call us to discuss your situation and we will tailor our involvement accordingly.

Nutrient neutrality catchment boundaries can be found on Defra’s Magic Maps application at magic.defra.gov.uk. The relevant map layers are: Designations > Land Based Designations > Statutory > Nutrient Neutrality Catchments. Alternatively, send us your site’s postcode and we will check for you.

If your site falls within a designated nutrient neutrality catchment, it is very likely that a NNAMS and sHRA will be required as a condition of submitting a planning application. These requirements vary by LPA, so always check with your local planning authority early in the project. You can also contact WCI with your site’s postcode and we will confirm whether it falls within an affected catchment.

A Shadow Habitats Regulations Assessment (sHRA) is a preliminary screening report that assesses whether a proposed development is likely to have a significant effect on a protected habitat site – typically a Special Area of Conservation (SAC), Special Protection Area (SPA) or Ramsar site. The report is submitted to the LPA, which uses it alongside its own Habitats Regulations Assessment. Like the NNAMS, it is frequently a validation requirement for planning applications in affected catchments.

A NNAMS is a Nutrient Neutrality Assessment and Mitigation Strategy. It is a technical report that calculates the nutrient load associated with a proposed development and sets out the measures – whether on-site or off-site – that will be used to achieve nutrient neutrality. Many Local Planning Authorities (LPAs) require a NNAMS as a validation document before they will accept and register a planning application.

Nutrient neutrality is a planning requirement, introduced in 2020, designed to ensure that new development does not increase the load of nitrogen and phosphorus entering sensitive water environments – particularly rivers, lakes and wetlands that are designated for their ecological importance. In simple terms, if a new development will generate nutrient pollution, the applicant must demonstrate that an equivalent or greater reduction in nutrients has been secured elsewhere before planning consent can be granted.

Option 1: Standard Terms – Most Common

• 10% non-refundable deposit upon credit reservation
• Up to 90% balance due on commencement

Minimal upfront exposure protects your project if planning is refused.

Deferred Payment – Large Outline Applications

• 10% non-refundable deposit upon credit reservation
• Balance payment deferred until Reserved Matters approval or closer to commencement

Designed for strategic allocations or outline permissions where construction commencement is years away. Improves cash flow management across long planning horizons.

Option 3: Upfront Payment

• Full payment upon credit reservation
• Potential discount for immediate settlement – discuss with WCI Nutrient Neutrality team

Suitable for funded developments seeking maximum cost certainty and potential pricing benefits.

Option 4: Bespoke Terms (Complex Developments)

• Custom payment structures for phased developments, land promotions, or unusual circumstances

Every project is different. Speak to our Nutrient Neutrality team to structure commercial terms that align with your specific planning and funding timeline.

Temporary phosphate offsetting for developments where permanent solution timing remains uncertain.

Useful for:

Outline permissions where construction timing is uncertain
Developments where on-site mitigation may become viable in future
Strategic allocations with long build-out programmes

WCI is uniquely positioned to deliver nutrient neutrality solutions. Our Consulting Engineers have produced more than 500 NNAMS reports and have a thorough understanding of development, planning and the regulatory environment. Our construction division has been installing sewage treatment plants for over 40 years. Our British Water-accredited Service Engineers are qualified to commission and maintain the treatment plants that generate our credits. And our balance sheet means we can deliver on our promises. We are a single source of expertise across the full nutrient neutrality process – from calculation to credit generation to monitoring.

Payment terms depend on how and when you purchase credits:

If you have secured your credits via a Reservation Notice prior to a planning decision, a 10% non-refundable deposit is due upfront, with the balance typically payable on planning approval. For large outline planning applications, payments are often deferred until closer to commencement.

If you purchase credits after planning approval has been granted, full payment is due on agreement of the purchase.

Please refer to the contract issued at the time of purchase for full payment terms.

Yes. WCI has bridging credits available across all of the catchments in which we operate. Contact our Nutrient Neutrality team to discuss eligibility and availability for your development.

Bridging credits are temporary phosphate credits that can be used to cover the difference between a development’s phosphate balance immediately after planning and its expected long-term balance. They are a tool to allow development to proceed while permanent mitigation is being put in place.

Somerset Council maintains a dedicated webpage listing approved third-party phosphate mitigation schemes in the Somerset Levels and Moors catchment area. WCI is listed as an approved scheme provider. You can verify this at somerset.gov.uk.

Yes. WCI holds P-Credits that are immediately available in the River Axe (Somerset), River Brue, River Parrett and River Tone catchments. Contact our Nutrient Neutrality team to confirm availability and discuss your requirements.

Our credits are priced competitively and tailored to your specific requirement. Please contact us with your development details and catchment area and we will provide a bespoke quote. We do not publish a standard per-credit rate as prices reflect scheme-specific factors.

WCI carries out all phosphate calculations as part of the NNAMS process. There are several recognised methodologies – including the Royal Haskoning method used by many LPAs and the Ricardo method promoted by Natural England. WCI uses the methodology approved by Somerset Council for use in the Somerset Levels and Moors catchment, ensuring your mitigation is accepted without challenge.

If your development is located within a phosphate-sensitive river catchment and the planning authority requires proof of nutrient neutrality, you will need to demonstrate that the phosphorus load your development generates will be offset. P-Credits are frequently the most practical and cost-effective way to achieve this, and can be secured quickly compared with on-site mitigation measures. WCI’s NNAMS report will confirm whether P-Credits are necessary and, if so, how many you need.

Phosphate credits, often referred to as P-Credits, are a type of off-site environmental mitigation that developers can purchase to make their developments nutrient neutral where the relevant planning policy applies. Each P-Credit represents a measurable reduction in phosphorus loading achieved elsewhere in the same river catchment – for example, by upgrading a failing septic tank to a sewage treatment plant capable of removing phosphate to a much higher standard. By purchasing credits equivalent to their development’s phosphorus impact, developers can demonstrate phosphate neutrality to their LPA.

There are three main running costs to factor in:

Electricity – the Graf sewage treatment plant is highly efficient. For an average domestic property, electricity consumption is less than that of a 60-watt lightbulb, equating to approximately £65 per year.

Emptying – the tank will need to be emptied on average every two to three years. You can arrange this with any approved tanker operator.

Annual servicing – under the General Binding Rules, sewage treatment plants must be serviced annually by a competent person. The cost is approximately £150 + VAT per year and will rise in line with inflation. WCI covers the cost of discharge monitoring for the first five years following installation under the scheme.

No. If you decide not to proceed with an upgrade, or if your property does not qualify for the scheme, your details will not be shared with any third party. All personal data is held securely in line with our privacy policy.

The Free Upgrade Scheme is not designed to respond to urgent or emergency situations. Funding for the scheme is directly linked to developer activity in the Somerset Levels and Moors catchment, and current market conditions – combined with a policy change allowing developers to receive planning consent without first securing a Reservation Notice – have significantly slowed the release of upgrade funding. A substantial wait is currently expected for scheme upgrades.

If your current system is failing and you cannot wait, WCI can still help – we have over 40 years of experience in off-mains drainage and can carry out a fast, fully funded paid installation outside of the free upgrade scheme. Contact us to discuss your options.

Shared systems can be upgraded. Both properties will need to enter into the legal agreement, and all owners whose properties feed into the shared tank must register and agree to proceed – we cannot advance the upgrade for one property if another shared owner declines. If you wish to separate your drainage from your neighbour’s under the scheme, this may be possible where a technically feasible separate discharge point exists, and we will assess this during the site survey. Please speak to your neighbours before contacting us, as we cannot negotiate with them on your behalf.

Your old septic tank will be emptied and decommissioned. Where it is close to the installation position of the new system, it will typically be infilled with compressible material and the area levelled. If the new system must be installed in exactly the same location, the old tank will be excavated and disposed of responsibly.

Most installations take between three and five working days, depending on the particulars of your property. Access constraints, landscaping and the complexity of the existing drainage layout can extend this. You will not need to move out during the works, and in almost every case you will continue to have the use of your foul drains throughout. We ask only that you minimise heavy water usage – such as running multiple laundry loads – for approximately 48 hours while the system is being connected.

Once the works are complete, the only visible above-ground element will be a small compressor housing – similar in appearance to a ventilation unit – positioned near a wall, hedge or outbuilding. You will also see one or two new inspection covers at ground level, depending on your property’s configuration. The installation area will be left level and tidy, though please note that WCI does not re-landscape, re-seed or re-turf gardens following installation – you will need to finish the garden to your own preference.

WCI installs Graf sewage treatment plants under the free upgrade scheme. Graf is a German manufacturer and their treatment plants are approved by Natural England for use in nutrient neutral areas under this type of scheme. The system is sized according to your property and in line with current Building Regulations.

Yes. The Graf sewage treatment plant installed under the scheme comes with a 15-year warranty on the tank itself and a three-year warranty on all serviceable parts, both provided by the manufacturer, Graf.

Yes. WCI supplies and installs the new system at no cost to you, but ownership transfers to you on completion of the works. The system is yours in the same way your boiler or your roof is yours – it will need routine maintenance over its operational life.

In exchange for the free installation, you will be required to enter into a Unilateral Undertaking – a planning agreement with Somerset Council. Under this agreement you will commit to: allowing the installation and decommissioning of the existing system; appointing a competent service provider to maintain the new system for its operational life; having the discharge from the new plant monitored annually (WCI carries out this monitoring free of charge for the first five years); only replacing the new system with one that delivers an equivalent or better level of treatment; and allowing the Council access to your property on 21 days’ notice to inspect the system. The agreement runs with the land, so any future owner of the property will inherit the same obligations.

To qualify for the scheme, you must: own a residential property with an existing septic tank; be located within an eligible catchment area in Somerset; and be willing to enter into a legal agreement with the Council committing to the ongoing maintenance of the new system. The scheme currently applies only to residential properties – it does not cover businesses, village halls, church halls or other non-residential uses, though residential properties with some commercial use (such as residential care homes) may be considered on a case-by-case basis.

Because the eligible areas do not neatly follow postcode boundaries, the simplest way to find out if your property qualifies is to register your interest and we will check your location using our mapping system.

The scheme is funded by developers who require phosphate credits to satisfy nutrient neutrality conditions attached to their planning consents within the Somerset Levels and Moors Ramsar catchment. When WCI upgrades a septic tank to a sewage treatment plant, the measurable reduction in phosphorus loading generates phosphate credits that can then be allocated to a developer’s planning mitigation. The homeowner pays nothing because the developer purchasing the credits is effectively covering the cost of the upgrade.

Yes – there is no charge to the homeowner for the installation of the new sewage treatment plant. The scheme covers the full cost of supply, installation and decommissioning of the old system. Please note that the scheme does not cover additional drainage work that may be required outside of the core installation scope – for example, removing rainwater connections from the foul drain, replacing damaged pipework upstream of the tank, or remedying failed drainage fields. If a site survey reveals that additional work is needed before installation can proceed, we will advise you and provide a separate quote for that work.

WCI’s Free Upgrade Scheme offers eligible homeowners in Somerset a completely free replacement of their existing septic tank with a modern, fully compliant Graf sewage treatment plant. There is no cost to the homeowner for the installation. The scheme is funded by developers who need to purchase phosphate credits to satisfy nutrient neutrality planning conditions in the Somerset Levels and Moors catchment area. When WCI installs a new sewage treatment plant and decommissions the old septic tank, the improvement in wastewater treatment quality generates the phosphate credits that developers need.

A soakaway is a pit or crate-based structure used for the attenuation and gradual release of rainwater (surface water) into the ground. Soakaways were historically used to receive septic tank effluent, but this has not been legal since 2007 and should not be confused with a drainage field.

A drainage field (also called an infiltration system) is the legal method of discharging treated effluent from a septic tank or sewage treatment plant to the ground. It consists of parallel, gravel-filled trenches fitted with perforated pipes, through which the effluent slowly percolates into the surrounding soil. Drainage fields must be designed and installed in accordance with British Standard BS 6297 and the relevant Building Regulations.

No. Rainwater and surface water should never enter a septic tank or sewage treatment plant. These systems are designed to treat sewage only, and are sized accordingly. Rainwater entering the system will overwhelm the treatment process, carry settled solids and bacteria into the drainage field or watercourse, and block or destroy the drainage field over time. Building Regulations (Part H) require rainwater and surface water drainage to be kept completely separate from foul drainage. If you suspect rainwater is entering your system, contact us – identifying and eliminating this is one of the most common and important maintenance interventions we carry out.

Yes. WCI has over 40 years of experience delivering foul drainage solutions for a wide range of commercial and large domestic applications, including systems serving multiple dwellings, campsites, hotels, visitor centres, care homes and industrial complexes. For commercial projects, we provide a full service: design, value engineering, installation, Environment Agency permitting, Building Control sign-off and ongoing maintenance. Call us to discuss your project.

Yes. For clients who already have a groundwork team on site, or who have the skills and resources to complete the installation themselves, WCI can design the system, supply the required tankage and components, and commission the system once it has been installed. We can also be available to provide technical guidance during installation if required.

Typically, the existing septic tank is emptied, decommissioned, infilled with suitable compressible material and the surrounding area is levelled and reinstated. If the new sewage treatment plant must be installed in exactly the same location as the existing tank, the old system will be fully excavated and the spoil disposed of responsibly.

Yes. All tankage and components installed by WCI come with the relevant manufacturer’s product warranty. WCI also provides a Workmanship Warranty covering our installation services, which is available to view on request.

You will need to submit a Building Control Notice before installation begins – this applies in all cases. Planning permission is more site-specific. All installation work within National Parks requires planning approval. Outside National Parks, small domestic installations usually fall under permitted development rights, but if you are in any doubt, we recommend consulting your local council’s planning department before proceeding. WCI can advise you on the consenting requirements for your specific site.

A standard domestic installation usually takes five working days. Where access is restricted or the installation is more complex, the programme may be longer. When we provide a quote, we will give you a clear estimate of the time required.

A straightforward domestic sewage treatment plant installation typically costs between £12,000 and £15,000, depending on the complexity of the site. Factors that affect cost include access, ground conditions, the need for groundwater management, the distance of the drainage field or watercourse from the tank, and whether the existing system needs to be excavated and removed. Contact us for a site-specific quote.

WCI is fully independent of all manufacturers, which means we select the right system for each site based on factors including cost, treatment performance, maintenance requirements, aesthetics, noise, access constraints, seasonal flow variations and the required quality of treated effluent. All systems are installed under a Building Regulation notice and will either comply with the General Binding Rules or have an appropriate Environment Agency permit applied for prior to installation.

We regularly install systems by GRAF, Marsh, WSc (formerly WPL), Premiertech Aqua, Klargester and others, and have experience with systems of all sizes and configurations.

Service Engineers carry out maintenance servicing, commissioning, emergency call-outs, compliance surveys and all forms of survey and testing for existing systems.

Consulting Engineers handle design, Environment Agency permitting, planning-related drainage assessments and expert witness work.

Nutrient Neutrality produces NNAMS and sHRA reports for developers, sells council-approved phosphate credits, and operates the Free Upgrade Scheme for eligible homeowners in Somerset.

Water & Wastewater Engineers (WWE) deliver the full scope of installation and groundworks, from straightforward domestic septic tank replacements to complex commercial multi-system contracts.

WCI does not operate tanker emptying services directly, but we are happy to recommend trusted emptying contractors in your area. The frequency with which a system needs emptying depends on its type, size and loading. Small domestic systems are typically emptied once every one to three years; commercial systems may need emptying every two to six months. When WCI services your system, we take a sludge reading and measure ammonia values in the discharge, which allows us to advise precisely when emptying is required.

WCI is not affiliated with any single manufacturer. This means we always recommend the system that best meets the individual needs of the site and the client, rather than the one we are commercially incentivised to sell. We are accredited installers and service providers for a range of systems and have experience installing, commissioning and servicing all makes and models of water and sewage-related equipment, including GRAF, Marsh, WSc, Premiertech Aqua, Klargester, Tricel, Xylem and TT Pumps, among many others.

Yes. WCI carries professional indemnity insurance, contractors all risks insurance, and public, employers and products liability insurance. All staff are trained and qualified to the appropriate level for their roles. Our Civil Engineers hold relevant engineering degrees, our Project Engineers are fully qualified surveyors and site managers, and our Service Engineers are in-house trained and British Water accredited. Our Workmanship Warranty for installation services is available on request.