What does the search cover, and what does it leave out?
The CON29DW answers a fixed set of questions about public assets: the sewers and water mains the water company owns, and whether the property connects to them. It is answered from the company's own records and maps. It says nothing about the condition of any pipe, public or private, and nothing about drains that were never adopted.
Where a finding is adverse, it is usually a cost rather than a barrier. A public sewer under the garden restricts where you can build and gives the water company a right to enter and excavate. A pumping station on the land may have transferred to the water company or may still be private: the Water Industry (Schemes for Adoption of Private Sewers) Regulations 2011 gave undertakers until 1 October 2016 to take over qualifying pumping stations, so one that did not qualify stays private (regulation 3(8)(b), checked 20 September 2026). A private supply or borehole brings testing obligations and can affect what a lender will accept.
| Revealed by the search | Not revealed |
|---|---|
| Whether foul and surface water drain to a public sewer | The condition of any drain or sewer, that needs a CCTV survey |
| A plan of public sewers and water mains near the property | The exact position of a pipe on the ground, plans are indicative |
| Whether a public sewer runs within the boundary | Private drains serving only the property, which are yours |
| Whether the supply is metered and where the main runs | The quality of a private water supply, that is a test |
| Whether drains and sewers are adopted or subject to an adoption agreement | Flood risk from rivers or surface water, that is the flood risk search |
| Whether a public sewer has been built over already | Whether a septic tank complies, that is the seller's reply plus inspection |
What if a public sewer runs under the garden?
It is common, particularly on terraced streets and older estates, and it does not stop a purchase. What it does is fix the rules for anything you build. Building over, or within three metres of the centreline of, a sewer shown on the map of sewers needs the water company's agreement, and the guidance to requirement H4 of Approved Document H applies whether or not that sewer is a public one (checked 20 September 2026). The company will usually want a CCTV survey showing the pipe is sound, a drawing of the foundations, and sometimes a lintel over the pipe or a diversion around it.
The paperwork matters afterwards as much as before. A future buyer's representative will ask for the build-over agreement, and its absence is a standard enquiry that ends in an indemnity policy or a price conversation. If the seller has already extended over a sewer with no agreement, we raise it now, so that the risk is priced or insured before you exchange rather than inherited.
What if the property has a septic tank or treatment plant?
Rural properties often drain to a septic tank, a package treatment plant or a cesspit, and the search will confirm there is no public sewer connection. In England the general binding rules for small sewage discharges apply: a septic tank discharging directly to a surface watercourse is no longer permitted and must be replaced with a treatment plant, connected to the mains, or redirected to a drainage field (Environment Agency general binding rules, page updated 2 October 2023, checked 20 September 2026). The guidance asks for this to be done as soon as possible, usually within twelve months, rather than by a fixed national deadline; the 1 January 2020 date often quoted comes from a separate rule about who carries the obligation when a property changes hands, so a buyer can inherit the cost of a replacement plant and should settle it before exchange. A tank discharging to ground must meet the rules on capacity and siting. Wales is not covered by those rules: there the discharge is registered with Natural Resources Wales as exempt under Schedule 3 to the Environmental Permitting (England and Wales) Regulations 2016, and a plain septic tank discharging to a watercourse is no more acceptable there than in England.
The seller's property information form asks about the system, its age, when it was last emptied and whether it complies. Where the answers are thin, we ask for the installation and maintenance records and, if needed, an inspection. A non-compliant system is a real cost, and the time to raise it is before exchange.