Shared Drains and Sewers: What Should Property Buyers Investigate?
Shared Drains and Sewers: What Should Property Buyers Investigate?
Drainage rarely receives much attention during a property viewing. However, blocked, damaged or poorly altered pipework can cause unpleasant disruption and potentially significant expense. The position becomes more complicated where drains are shared with neighbouring properties.
Before exchanging contracts, buyers should understand what drainage serves the property, who is responsible for it and whether extensions or other alterations have affected the system.
What Is the Difference Between a Drain and a Sewer?
A private drain generally carries wastewater from one property. A sewer receives wastewater from more than one property, while a lateral drain carries waste from an individual property outside its boundary before reaching a sewer.
Since October 2011, many shared sewers and lateral drains in England and Wales have been the responsibility of the regional sewerage company. Nevertheless, homeowners usually remain responsible for private drains within their property boundary that serve only their home. The precise position depends on the pipe’s route, use and connection. Buyers should therefore avoid assuming that every pipe beneath the garden is either privately owned or maintained by the water company.
Why Do Shared Drains Matter When Buying?
A drainage problem can affect several properties rather than only the home being purchased. A blockage downstream could cause wastewater to back up through an inspection chamber, toilet or ground-floor appliance.
Responsibility for repairs may depend on whether the affected section is a private drain or a public sewer. Even where the water company is responsible, access may still be required through the property. Shared arrangements can also become contentious when ownership or maintenance responsibilities have not been clearly understood by neighbours.
Look for Warning Signs
During an inspection, a surveyor may identify indications of drainage trouble, including:
· damaged or overflowing inspection chambers;
· persistent unpleasant smells;
· unusually slow-draining sanitary fittings;
· localised dampness close to drainage routes;
· cracked paving or settlement around chambers;
· mature trees growing close to underground pipes;
· evidence of recurring excavation or patch repairs; and
· extensions constructed over or close to drains.
These signs do not necessarily prove that a pipe has failed. However, they can justify further investigation before the purchase becomes legally binding.
Consider a CCTV Drainage Survey
Most underground drains cannot be assessed fully as part of a visual building survey. Inspection chambers may be opened when they are safely accessible and within the survey’s agreed scope, but this provides only a limited view. A specialist CCTV drainage survey can examine the inside of accessible pipework. It can identify displaced joints, fractures, root penetration, obstructions, deformation or poor connections. CCTV footage can also help establish the approximate route and condition of the drainage system. This is particularly worthwhile where the property is older, has experienced previous blockages or has been extended. Any concerns should be investigated by an appropriately qualified drainage contractor.
Has an Extension Been Built Over a Sewer?
Rear extensions, conservatories and garages are sometimes constructed above or close to existing drains. Where the pipe is a public sewer, the work may have required the sewerage company’s approval or a build-over agreement. Building over a sewer without appropriate consideration can restrict access for maintenance and expose the structure to movement or damage if the pipe fails. Buyers should ask their solicitor to check for:
· a build-over agreement;
· Building Regulations approval;
· drainage plans;
· completion documentation; and
· guarantees or records relating to drainage alterations.
The absence of paperwork does not automatically establish that the work is defective, but it should be investigated before exchange.
Check the Property’s Drainage Search
The buyer’s solicitor will normally obtain a water and drainage search. This may indicate whether the property connects to mains drainage and whether public sewers are recorded nearby. However, plans may not show every private or formerly private pipe accurately. The visible arrangement on site may also differ from the documented route, particularly at older or altered properties. The legal search, survey findings and any specialist drainage investigation should therefore be considered together.
Foul Water and Surface Water
Buyers should also establish how foul water and rainwater are discharged. Some properties use separate systems, while older areas may have combined sewers. Incorrect connections can send foul water into a surface-water drain or direct excessive rainwater into an unsuitable system. Where the property has a septic tank, cesspit or treatment plant, additional legal, maintenance and environmental considerations apply.
Trees and Ground Movement
Tree roots can enter defective joints and gradually obstruct or damage underground pipes. Leaking drains can also soften or wash away surrounding soil, potentially contributing to localised movement. Drainage defects are not the only possible cause of cracking or settlement. Nevertheless, where structural movement is visible near a drain, both issues may require further investigation.
What Should Buyers Do Before Exchange?
If drainage concerns arise, buyers should ask their surveyor, solicitor and drainage specialist to clarify the position. Depending on the findings, it may be appropriate to obtain repair quotations, request further documents or reconsider the proposed purchase price. A RICS Level 3 Survey can be particularly useful for older, altered or visibly defective properties because it provides a detailed assessment of accessible construction and highlights areas requiring specialist investigation. Further information about Rectory Surveyors’ home surveys is available at:
To discuss a property before purchase, contact Rectory Surveyors at:
Conclusion
Shared drainage should not be treated as a minor detail. Establishing the likely pipe routes, ownership, condition and history of alterations before exchange can help buyers avoid unexpected blockages, disputes and repair costs after completion.
Rectory Surveyors are experts in building and surveying, friendly and experienced, with a high degree of professionalism for all your surveying requirements. Learn more >
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