Residential drain surveys: using a certified surveyor

What’s going on down here?

31 January 2017

In the second in our series on surveys, Martin Beattie explains the importance of using a certified drain surveyor

Damaged drains can be the source of many problems other than the unpleasantness associated with resultant blockages. Most private drainage systems are built of vitrified clay and are around 100 years old; they commonly suffer from joint displacements, fractures and breaks, all of which allow exfiltration and infiltration of liquids into and out of the surrounding material. Over time, the washing away of fine material from the surrounding earth results in void areas, and what was a relatively minor issue is exacerbated into a major problem.

At some point the drain is likely to require repair or replacement, but this may also have a detrimental effect on nearby structures. Such erosion close to building foundations can lead to more serious structural issues.

A HomeBuyer Report will typically cover all aspects of the property:

  • interior;
  • exterior;
  • services (gas, electrics and water); and
  • surrounding grounds.


It makes sense to recommend a drainage survey in the form of a CCTV investigation, especially if there are signs of movement or damp, and this will be conducted by a specialist contractor. Some surveyors recommend these investigations as a matter of course; a drain is an important part of a property’s infrastructure, yet difficult to survey without the correct equipment, so this process is not normally carried out by an RICS surveyor.

There has traditionally been an issue with the quality of the drainage contractor’s information, because there was no agreed standard throughout the domestic or commercial drainage sector and little in the way of certification; the criteria for using a particular contractor would probably have ranged from recommendation to cost. This has been largely resolved with the introduction of Certified Drain Surveyor (CDS) status by the National Association of Drainage Contractors (NADC).

Certified drainage contractors

In conjunction with the Water Research Centre and the Environment Agency (EA), an EU skills-registered course has been established to train and certify drainage contractors working at domestic and light commercial sites. The course is based on the Manual of sewer condition classification, which assesses drainage defects and the general state of the system. There has also been input from the EA on the increasingly important issue of misconnections and resultant watercourse pollution.

Damaged drains can be the source of many problems other than the unpleasantness associated with resultant blockages

Although the course focuses on condition assessment, there are other modules that concentrate on drain ownership and mapping, drainage law and investigation, as well as selection and specification of the correct repair techniques. The result, after rigorous examination, is a qualified drain surveyor working to a nationally recognised objective standard. Operatives who have completed this course receive a certificate and an identification card, while their details are held on a national database for potential verification purposes, ensuring quality and security.

Using software of a reporting industry standard is also encouraged. This ensures that the drainage contractor’s CCTV condition report not only complies with water utilities’ specifications but also enables a report with images, defect grading and colour coding. It is important that this is easily understood by the customer. Contractors will then base any remedial recommendations on the report.

Employing an NADC CDS ensures the work will be carried out correctly, and their report, which is valid for 5 years, will normally include:

  • information relating to ownership – whether it is private or belongs to the water company – and thus responsibility;
  • an accurate drawing;
  • correct investigation techniques;
  • an easy to understand, concise condition report with images and footage;
  • accurate remedial recommendations concerning any pipe/manhole or other drainage asset using the Sewerage rehabilitation manual/Drain repair book grading systems;
  • legislation and regulation concerning repair: Building Regulations, Part H;
  • a complete understanding of the regulations and issues that relate to misconnections, pumping stations, sewage treatment plants as well as drainage fields;
  • structural condition reporting/analysis;
  • mapping/drawing to show drainage system locations and components; and
  • detection of vermin/rat infestation in the drainage system.

Advantages for all parties

A survey might be recommended as a consequence of a known issue, the need to establish ownership or at the request of a mortgage lender or insurance company. These reports will satisfy and reassure all parties involved, including solicitors who are conducting CON29DWs (water searches). The reports will enable the following:

  • homebuyers will be made aware of drains that may be in very poor condition;
  • the local water company will be forewarned about any defects with its asset, saving time and money associated with repairs and preventing the buyer from inheriting problems; and
  • insurance companies will be informed of the true condition before deciding to provide cover for drains.

The important thing to remember is that if a drain survey is recommended, then it should be carried out by a competent person. A qualified NADC CDS will provide that confidence for both you and your client.

Martin Beattie is Vice-Chairman of the National Association of Drainage Contractors

Further information

This feature is taken from the RICS Property journal (November 2016)