Drain Reports

At a glance...

  • CCTV cameras record the condition of the drains.
  •  Clear blockages/ upgrade/ replace.
  •  Septic tank/ cesspits.
  •  Report format acceptable to lenders with costings.
  •  You will have the report back in hand quickly.

There are many factors that can lead to a surveyor or valuer recommending a drain report. The most obvious reason is when drains are blocked and need to be cleaned. Symptoms of blockage are usually obvious in domestic dwellings – sanitary appliances fail to clear properly etc, though in other settings, failed drains can be behind localised flooding.

However, there are many other signs that drains may need checking. For example, leaking drains can erode subsoil and can cause localised movement in buildings. Where cracking indicates settlement of foundations and a drain runs close by, there is good reason to have drains tested. A good percentage of structural movement in domestic property stems from drainage problems. Another reason to suspect the integrity of drains is when tree or shrub roots pass close to the run. Roots seek out water in whatever shape of form it comes and can easily break into joints of most types of drain pipework. Well worth a check, therefore, to avoid expensive surprise repairs.

What is for sure, however, if you are advised by a professional to have a drains test carried out, you should certainly do so when advised and not delay it for to long.

All surveyors carrying out a drain inspection will need first to plot the drainage runs. This will mean identifying inspection chambers, which mark changes of direction or gradient and the braches of drains that run between them. The report will note the condition of the chambers and the cement that runs adjacent to the drains within the chamber (called ‘benching’).

Most reports will include a site diagram showing the property and the layout of the drains in relation to the property and grounds. The diagram will normally label (number) the inspection chambers to which reference is made throughout the report.  The diagram should also indicate the direction of ‘fall’ of the drain which will eventually discharge into the public sewer.

The report will bring your attention to who is responsible for the sections of drains which might need repair.

The body of the report will provide a REPORT OF FINDINGS. This highlights defects discovered within the drainage system Some reports present these findings as a chart of defects which are ticked if present – others present their findings in text.

Typical defects noted in these sections include matters such as water holding within the drain; damage to joints; cracks to drain (radial or long); crushed pipework; silt deposits; intrusion by tree or shrub roots; scale etc.

Clients will be alerted to the cause of the problem and given a list of recommended actions/repairs. Each recommendation will have a cost attached to it, giving a very clear assessment of your liabilities with regard to the drains.

A good drain contractor will alert you to any likely implications for others, for example if the drain runs very close to a boundary or neighbour’s property.

Drain reports will normally involve a scan of the inside of the drain run using a CCTV camera. This records a DVD of the drain, linked to measured distances, so defects within the drain can be pinpointed for repair. The report may include a copy of the DVD showing the drain or selected photographs from the DVD if these are relevant and helpful in identifying the condition and repairs which the report recommends.

Obviously, a CCTV scan cannot be made of a drain that is blocked and it will be necessary, therefore, for the drain to be cleared first. If this hasn’t been identified by the surveyor or valuer who recommended the drains test, then a good contractor will seek to contact the client from site to agree to the additional cleaning works together with any additional costs involved.

Sometimes drains will leak due to normal wear and tear and degradation of the materials, other times because the subsoil has moved slightly or due to accidental damage. With older clay pipes, even small movements of bedding material can put pressure on pipework, particularly close to joint positions which can result in failure. This most commonly manifests itself in open joints, cracked pipes or sections of the run that collapse.

In other situations, external factors come into play. Tree and shrub roots are particularly damaging to drains. Trees such as Willow and Poplar are amongst the worst at seeking out water sources even some distance away from the tree trunk. Roots are more than capable of breaking into drains at joint positions or cracks or even at inspection chamber positions, causing leakage.

Another common reason for the failure of drains to function correctly is poor design/construction. To properly discharge waste materials and/or liquids, drains have to lay at a certain gradient. This is known as the ‘fall’ of the drain. There are recommended falls for drains depending on the size of the drain and the length of run.

Where the fall isn’t great enough, deposits can collect which in time leads to blockage. It is why it is always helpful to flush through domestic drains on a regular basis with warm water.

In October  2011, responsibility for maintaining drains changed throughout England and Wales.
Essentially, the responsibilities have simplified. Since October 2011, any private drain run that lies within the boundary (curtiledge) of a property owner’s site is the responsibility of the owner. Everything outside the boundary will be the responsibility of the appropriate water authority.

However, the water authority is also responsible for drainage runs within the curtiledge of an owner’s site where those runs are shared drains with other properties.

So, water authorities will now be obliged to deal with repairs and drainage problems under public highways and areas outside of owned properties such as greens or footpaths.

There are a number of different types of tests for drainage, though the most common for domestic property is now the CCTV scan.

Other tests, however, include a water/air pressure test, where the drain is sealed and put under pressure to assess the amount of leakage. The danger when applying this to older drains is that they weren’t designed to run full and the pressure applied can even damage joints causing leaks rather than highlighting them.

Dye tests are occasionally used to check discharge of waters when direction and flow is unclear.  This is useful when soakaways are being checked or the discharge of water via land drains.

In addition to these, drains contractors will carry out a range of works and service linked to drain runs. These will include rodding or jetting to clear blockage, root removal; repairing or rebuilding inspections chambers water authorities will now be obliged to deal with repairs and drainage problems under public highways

A quick note on these as they are often a matter of confusion for many.

These drainage systems are needed when a property is not connected to the public sewer. In such circumstances, drainage waste has to be collected and stored in a chamber until it is taken away by a specialist company (a cesspool) or collected and treated on site until it can be discharged into the soil around the property (a septic tank, sometimes called a domestic treatment facility). Soakaways are usually used to discharge rainwater into the soil a safe distance away from the foundation to avoid damage to soil support the foundations.


Cesspools are essentially tanks that hold untreated sewerage until it is collected by a specialist company. They will need emptying regularly and it well worth while establishing how often, and at what cost, it has been emptied in the past. Obviously, the regularity of emptying will depend on usage (number of people living in the property) and the size of the chamber, though previous experience and costs are a good guide.

It is essential that cesspools are watertight to prevent water entering them when they are empty and also to prevent contaminated effluent escaping into the surrounding ground. Older cesspools are at risk of behaving like septic tanks and allowing water to percolate through its walls into adjacent soil. This is a serious problem. Overflow of the chamber of the chamber could give rise to health risks and even legal actions in respect of nuisance, so regularly emptying is an essential.

The positioning of cesspools is important – close enough to allow vehicles to empty the tanks but far enough from buildings and watercourses to avoid contamination.

Septic Tanks

These are essentially mini sewerage treatment installations. Most have two (sometimes three) chambers and they work on the principle that discharged solids are collected and settle within the chambers. Bacteria then breakdown the material in the chambers.

This is usually not totally effective due to the volume and type of discharge from modern homes. Excess liquid is discharged into surrounding ground by perforated or open jointed pipes often laid in a herringbone pattern.

Older tanks are built of bricks with new tanks made of glass reinforced plastic.

Septic tanks need to be cleared out of sedimentary waste at regular intervals.


Soakaways allow rainwater to be discharged to soil a safe distance from buildings. The volume of rain water to be dealt with and the ability of the surrounding soil to take the water without flooding will determine what size the soakaway should be designed to be.

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