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Home-Buyer's Drainage Survey

A Home-Buyer’s Drainage Survey is a comprehensive assessment of the functionality and compliance of a property’s foul and surface water drainage.  WCI offers home-buyer drainage surveys and CCTV condition surveys in Somerset, Devon, Dorset and Wiltshire.

What is a Home-Buyer’s Drainage Survey?

Our Home-Buyer’s Drainage Survey is a comprehensive assessment of the functionality and compliance of a property’s foul and surface water drainage.

The purchase of property in England and Wales is ‘as seen’ and it is the buyer’s responsibility to determine whether the property’s foul and surface water drainage is fit-for-purpose and legally compliant.  WCI’s Home-Buyer’s Drainage Survey identifies potential problems and helps to explain what the cost of resolving these problems will be so that you can get on with buying or selling your home.

What’s included in our Drainage Surveys?

WCI offers two levels of survey – the Standard Survey and Advanced Survey. Our Home-Buyer’s Drainage Surveys are offered at a fixed price and our reports are delivered without delay.  Our reports are often used to support negotiations between buyer and seller.

Please contact WCI on 01984 623404 to book a survey and for pricing.


Our Standard Survey includes a thorough assessment of the property’s drainage system:

  • Drainage map showing where and what drainage a property has.
  • Compliance assessment to check whether the property’s drainage is compliant with the necessary environmental and building regulations.
  • Functionality assessment including sizing checks, defects checks and maintenance checks.
  • Full written report with recommendations and budget figures for repair or replacement.

What is different about WCI’s Drainage Survey?

There are many different things to consider when buying or selling a property.  A typical RICS homebuyer’s report or building survey will look at the property as a whole but rarely investigates drainage fully.

At the other end of the scale, a CCTV condition survey only looks at the condition of the pipes without considering the legality and functionality of the drainage system as a whole.

WCI’s Home-Buyer’s Drainage Survey is a comprehensive survey of a property’s drainage system including the drains, septic tanks, sewage treatment plants, drainage fields, reed-beds and other drainage systems.  As professional wastewater engineers, our surveys focus on providing an understanding of:

    • What drainage system a property actually has
    • The functionality and performance of a property’s drainage
    • The legal compliance of the property’s drainage


Our Advanced Survey includes everything that our Standard Survey offers, with the addition of a full CCTV condition survey of the property’s drains:

  • CCTV condition survey of accessible drains using latest self-levelling CCTV drainage cameras.
  • Industry-leading WinCan condition report.
  • Guidance on the relevancy of any defects found and the most appropriate method of repair.

What if WCI finds a problem?

Where our Home-Buyer’s Drainage Surveys identify issues with a property’s drainage, we will include independent and objective recommendations and budget costs for bringing the property’s drainage up to standard.

We are also able to assist with completing the work required.  For example:

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Dye testing of septic tank showing a clear relationship with the watercourse

Home Buyers Drainage Survey FAQs

My solicitor wants to ensure the septic tank is compliant with the Environment Agency 2020 rules. Is this included in the report?

Yes. We provide a complete assessment of a drainage systems compliance with relevant regulations including the Environment Agency 2020 rules (which form part of the Environmental Permitting Regulations). You can read more about the General Binding Rules here.

Is the report only for people purchasing a property?

No. It can be used by buyers, sellers and owners not selling who would like a system MOT.

WCI are often approached by people purchasing a property who have been recommended by their surveyor or solicitor to undertake a professional inspection of their septic tank. Most requests are made late on in the sales process, often delaying the date of exchange. As a home owner looking to put your property on the market, you can avoid costly delays by arranging for your septic tank to be inspected before sale. This means any issues arising from the inspection can be addressed before it can affect a sale. Armed with an up-to-date written report about the functionality and compliance of your foul drainage system, you can provide the purchaser with all the information they desire. In this way, questions about the septic tank won’t hold up the sale!

What are the benefits of a CCTV condition survey?

CCTV surveys are able to uncover a number of potential defects within a drainage system. While the most common instance is a simple blockage due to soap scum, hair or food residue, these investigations can also detect cracks in a pipe, joint displacements, root ingress or a collapse of the pipe itself.

Should I get the septic tank emptied before the inspection?

No. We can tell a lot more about a tank which is full than we can about one that has been recently emptied. WCI likes to see a tank in its ‘normal’ operating state. We can then assess things like working level of the tank and signs of drains having previously backed up. With a full septic tank, we are also able to dye test the discharge pipe work to ensure it does not discharge to a ditch or stream! Where the owner of the tank is agreeable, WCI also suggests that the septic tank is emptied whilst we are at the property after our initial inspection so that we can make further checks including the physical condition of the septic tank.

What should I ask the seller about the septic tank I am inheriting?

When purchasing a property with a septic tank it is crucial to learn as much as possible about the foul drainage system in place. Any information that can be gleaned from the seller should be passed on the engineer that comes out to survey the system. The more information the better! WCI would suggest asking the following questions:

    1. Is the septic tank shared with other properties?
        • How many bedrooms does each property have?
    2. Where is the septic tank and drainage field / soakaway located?
        • Is it on land owned by you or a third party?
        • Is there an easement in place if the system is not on your land?
        • Do you have rights of access, and is a management company in place which sets out maintenance and emptying arrangements and payment of such activities?
    3. How old is the septic tank and drainage field?
        • Who installed it?
        • Is there a Building Completion Certificate covering the installation of the septic tank?
    4. How often has the septic tank been emptied?
        • Has the seller kept receipts of each empty?
    5. Do you know of any wells or boreholes for potable water nearby?
        • Drainage fields can not be located within 50m of any well, spring or borehole that is used to supply water for domestic or food production purposes.
    6. Have you experienced any issues with the system?
        • These could include backing up of drains, smells, a need to empty the septic tank more frequently, blockages or wet patches over the drainage field.
    7. Is there any history of problems especially during wet weather?
        • Either when the groundwater sits closer to the surface or rainwater gets into the wastewater treatment system?

My seller refers to the existing system as a cesspit. What is this?

Often people will refer to a septic tank as a cesspit. The easiest way to check is to ask how often it is emptied. Septic tanks receive incoming raw sewage from a property, settle out the solids and allow the clarified effluent to discharge into a drainage field (which is commonly referred to as a soakaway). Septic tanks require emptying between every 6 months and 2 years. Should the tank be a cesspool which is a large storage tank without an outlet, the tank would be need to be emptied much more frequently!

What are the limitations with a septic tank and drainage field survey?

It sounds simple but because the installed system is underground, access to the system is not straight forward. A septic tank is always full of water and depending on its construction, it may not be possible to see into the tank (even when it’s empty). The drainage field / soakaway that should be installed after the septic tank will (if designed properly) consist of trenches underground, partially filled with clean large stone, on which a solid perforated pipe is laid, further surrounded by more stone, a geotextile membrane and backfilled with soil to ground level.

Access to the drainage field for a CCTV survey is often difficult or disruptive and if access to the pipe work can be arranged, then the camera can very rarely inspect all of the pipework and very little can be seen from inside the pipe.

WCI engineers therefore have to rely on over thirty years of wastewater engineering experience, not only of inspecting systems but of also installing and maintaining them, to read the clues that the system and the site show us.

I know that my rainwater enters my septic tank. Is this allowed?

No. Building Regulations require separate soakaways for foul water and rainwater. After dye testing and mapping of your foul drainage system, if rain water is found to enter the septic tank, the foul drainage report will detail how this can be separated, a budget cost and how this can be done.