Drainage (from a building, as opposed to within a building) is invariably underground and can only be seen at inspection chambers (manholes). Out of sight usually means out of mind and so it tends to be ignored until it misbehaves.
Often referred to as a 'simple drains test' (SDT). This is often carried out by the Surveyor at the same time as a Homebuyer Survey or Building Survey. It simply involves lifting manhole covers and running water through the drain runs from the taps within the property, whilst observing the flows throughout the drainage system. This allows the Surveyor to check if the drains are running free, or if there are blockages, and will also indicate any severe leakage.
Water Test (WT)
Leaking drains very often go undetected for years or decades, but if close to the building, the ground beneath the foundations can be weakened by the water, resulting in subsidence. It is for this reason that Surveyors may request a drainage report when they have seen cracking or other indications of foundation movement.
In these cases, a water, or hydraulic, test is required. This involves plugging the drain at the lower end, filling it up with water, then waiting to see if it holds the water or if it leaks away. When the plug is removed, the water should flow away rapidly to indicate that the drain is not blocked. There may be several sections of the drainage, each of which will require testing separately.
CCTV Survey (CCTV)
CCTV surveys involve passing a small camera through the drains. The operator watches the picture as the camera progresses, so that any features can be closely examined and identified, and a video recording is usually made for later reference.
A CCTV survey will not determine that a drain is watertight, but it will show and locate areas of damage or blockage. A CCTV survey can also be useful in determining the layout of a drainage system and identifying unknown / abandoned branches.
Drains can be tested and surveyed quite easily if there are adequate inspection chambers, and if they are not blocked. However, especially with older properties, there may be few or no inspection chambers. In these cases, the only way to test and survey the drains is to dig holes and break into the pipes - this gets expensive! We often find drains are blocked, or are backing up from overfull cess pits or septic tanks. In these circumstances, there is little which can be done until the system has been unblocked, cleared or emptied - again an expensive operation.
A drainage report would normally include a plan showing the layout of the drains, along with details of pipe diameters, depths below ground, results of water tests, and findings of CCTV surveys.
So that we can provide you with an estimate of the cost of a Drainage CCTV Report, please fill in the following form to request an estimate. We will then email you a list of Experts in your area, together with an estimate of their costs.