What is a septic tank survey?

Written By Tim Buckley

Why Septic Tank Surveys Are More Important Than Ever

If you own a rural property, are buying a house with a septic system, or are planning to sell your home, a septic tank survey is no longer just a “nice to have”, it is an essential part of understanding whether your drainage system complies with modern regulations and whether it could become a costly issue in the future.

At Clearflow Surveys, we regularly carry out septic tank surveys across Cheshire, Staffordshire and Greater Manchester. In recent years, we’ve seen an increase in homeowners, buyers and solicitors requesting these inspections due to tightening regulations and growing awareness around non-compliant systems.

One of the biggest misconceptions we hear is: “If the septic tank still works, it must be compliant”. Unfortunately, that is completely wrong.

Many septic systems installed decades ago no longer meet current regulations, even if they appear to function perfectly well. We regularly find systems discharging illegally into watercourses, drainage fields that fail current standards and shared arrangements that create major complications during property sales.

In some cases, homeowners only discover these issues after accepting an offer on their property, leaving them facing replacement costs of £10,000–£20,000 or more. This is why septic tank surveys have become such an important part of rural property ownership and transactions.

What Is a Septic Tank Survey?

A septic tank survey is a detailed inspection of a property’s private drainage system to assess:

  • The condition of the septic tank

  • The condition of the inlet and outlet pipework

  • Where the system discharges to

  • Whether the system complies with current regulations

  • Whether there are any defects, risks or future liabilities

At Clearflow Surveys, our septic tank inspections combine:

  • A visual inspection of the tank itself

  • A CCTV drain survey of inlet and outlet pipework

  • Investigation of outfall arrangements

  • Assessment of the tank’s location relative to nearby buildings and boundaries

  • WRC-approved reporting with video footage and recommendations

Our surveys are designed to give homeowners and buyers a clear understanding of the condition and compliance of the system before problems arise.

Why Are Septic Tank Surveys So Important Today?

The regulations surrounding septic systems have changed significantly over recent years. Historically, many rural properties discharged directly into streams, ditches or watercourses. Under modern legislation, many of these arrangements are now illegal unless the system has been upgraded to a sewage treatment plant.

The issue is that many homeowners simply don’t realise this. We regularly inspect systems that have operated for decades without issue but are technically non-compliant under current regulations. This becomes particularly important during:

  • Property sales

  • House purchases

  • Mortgage applications

  • Extensions and conversions

  • Boundary or neighbour disputes

  • Environmental complaints

Buyers are becoming far more aware of septic system liabilities and solicitors are increasingly raising enquiries around drainage arrangements during conveyancing.

What Do We Inspect During a Septic Tank Survey?

A proper septic tank survey should go far beyond simply lifting a lid and taking a quick look. At Clearflow Surveys, a typical septic tank survey includes several stages.

1. Visual Inspection of the Septic Tank

Before our visit, we usually recommend that the tank is emptied so we can properly inspect the internal condition. We check for:

  • Structural damage

  • Cracks

  • Evidence of collapse

  • Signs of leakage

  • Poor installation

  • Deterioration in older brick or concrete tanks

Interestingly, older brick tanks are not automatically a problem. If the overall system and outfall arrangements comply with regulations, many older systems can still remain serviceable.

2. CCTV Drain Survey

We carry out a CCTV inspection of the inlet and outlet pipework using high-specification survey cameras. This allows us to identify:

  • Blockages

  • Cracks

  • Root ingress

  • Collapsed pipework

  • Incorrect connections

  • Poor falls

  • Structural defects

General homebuyer surveys and mortgage valuations rarely investigate drainage systems in this level of detail.

3. Investigation of the Outfall Arrangement

This is one of the most important parts of any septic tank survey. We investigate exactly where the system discharges to, including:

  • Drainage fields

  • Soakaways

  • Watercourses

  • Existing treatment systems

The outfall arrangement is often where major compliance issues are identified. If a septic tank discharges directly into a stream or watercourse, this may require the installation of a sewage treatment plant to comply with current regulations.

4. Assessment of System Location

We also assess the position of:

  • The septic tank

  • Pipework

  • Drainage fields

  • Nearby buildings and extensions

There are regulations around how close septic systems and outfall arrangements should be to structures. We have seen multiple property sales collapse due to systems being positioned too close to neighbouring properties or extensions.

Common Problems We Find During Septic Tank Surveys

Over the years, we’ve encountered a huge range of drainage and compliance issues. Some of the most common include:

  • Septic tanks discharging into watercourses

  • Failed soakaways or drainage fields

  • Shared systems between neighbouring properties

  • Unknown outfall locations

  • Inaccessible tanks

  • Pipework crossing neighbouring land

  • Poor historical installations

  • Non-compliant drainage arrangements

  • Tanks located too close to buildings

In many cases, homeowners are completely unaware of these issues until a survey is carried out.

Real Example: Shared Septic System Causing Property Sale Issues

We are currently working on a project involving three Grade II listed properties in Timbersbrook, just outside Congleton. The issue first came to light when one homeowner decided to sell their property and was advised that the shared septic arrangement could become problematic during the transaction. The three properties were connected to a shared septic system installed many years ago.

Following investigation, we carried out:

  • Percolation testing

  • Drainage assessments

  • Design work for replacement systems

We then designed a new arrangement to separate the shared system into individual private systems with new drainage field and we are working with our client to install this system. This is becoming increasingly common as homeowners look to avoid future legal and ownership complications surrounding shared septic infrastructure.

Example of a Failed Property Sale

We’ve also seen cases where buyers have pulled out entirely after discovering serious drainage compliance issues. In one case, the septic tank was located approximately 1.5 metres from a neighbouring property extension, while the drainage field was also positioned too close to the building - with ground movement being a risk over time.

The homeowner had multiple buyers withdraw from the purchase after the issues were identified. Situations like this demonstrate why arranging a septic tank survey early can prevent major disruption later in the sales process.

What Happens If a Septic Tank Is Non-Compliant?

If a septic system does not meet regulations, the solution depends on the severity of the issue. In some cases, repairs or drainage improvements may be sufficient. In others, the septic tank may need to be decommissioned and replaced with a sewage treatment plant. Typical replacement projects can cost:

  • £10,000–£20,000+ depending on:

  • Site access

  • Ground conditions

  • Outfall requirements

This is why a survey costing from around £300 can potentially save buyers and homeowners significant future costs.

When Should You Arrange a Septic Tank Survey?

We generally recommend arranging a septic tank survey:

  • Before buying a rural property

  • Before selling a property

  • If you experience recurring blockages

  • If there are smells or drainage issues

  • Before extending a property

  • If you are unsure whether your system complies

For buyers in particular, arranging a survey early is critical. Once you purchase the property, responsibility for the septic system transfers to you.

What Does a Septic Tank Survey Cost?

At Clearflow Surveys, septic tank surveys typically start from around £300, although costs can increase depending on:

  • Property size

  • Complexity of the drainage network

  • Accessibility

  • Number of systems

  • Extent of investigation required

A typical survey takes:

  • 1–2 hours on site

  • Up to 48 hours for reporting

Afterwards, clients receive:

  • A detailed WRC-approved report

  • CCTV footage

  • Images of defects

  • Site plans

  • Compliance recommendations

Septic Tank Survey FAQs

Are old septic tanks automatically compliant?

No. Older systems are not “grandfathered” into compliance simply because they have existed for a long time.

Do mortgage surveys check septic tanks?

Not usually in detail. Most mortgage valuations only carry out basic visual observations and do not assess compliance or drainage condition thoroughly.

Is it illegal for a septic tank to discharge into a stream?

In many cases, yes. Older septic tanks discharging directly into watercourses may require replacement with a sewage treatment plant.

Are shared septic tanks a problem?

They can be. Shared systems often create legal, maintenance and ownership complications during property sales.

How often should a septic tank be emptied?

This depends on tank size and usage, but regular emptying and ongoing maintenance are essential to keep systems functioning correctly.

Final Thoughts

Septic systems are an essential part of rural living and, when properly maintained, can work extremely well for many years. However, regulations and buyer expectations are changing rapidly. What worked twenty years ago may no longer comply today.

At Clearflow Surveys, we regularly help homeowners, buyers and property professionals identify hidden drainage issues before they become expensive legal or environmental problems. Our advice is simple:

If you are buying or selling a rural property, arrange a septic tank survey early.

The cost of a professional inspection is small compared to the financial risk of discovering a major compliance issue after contracts are exchanged.

Speak to Our Team

If you are buying or selling a property with a septic tank, or you are concerned about whether your system complies with current regulations, speak to our team today.

Clearflow Surveys provides professional septic tank surveys, CCTV drain surveys, drainage investigations and compliance reporting across Cheshire, Staffordshire and Greater Manchester.

Tim Buckley
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