Can a developer plug in to our private drain scheme for his new build?

I live in a row of 10 terraced houses that are served by a private drain that runs to the public sewer. I was surprised to learn recently that a developer, who is building a new detached house on a site adjacent to our terrace, is looking to connect this new house to the existing private drain. The planning permission says little about this issue other than the developer must comply with our local authority’s requirements. The local authority drainage division report on the planning file says the developer needs a completely separate drain.

Can the developer connect to our existing private drain? Does he need permission from the owners of the 10 houses? What can we do to make sure he doesn’t do this unknown to us?

I might start by explaining the difference between a private drain and a public sewer. A private drain is a single pipe which removes sewage or rainwater from one or more houses. It is not owned or controlled by Irish Water. It can go past the boundary and under the road until it joins a main sewer.

A public sewer is a drain which has been taken-in-charge by the local authority (on behalf of Irish Water) as a public sewer and is therefore the responsibility of the county council. The council is not responsible for maintaining private drains. This falls to the individual house owners.

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I assume your drain is a combined (foul and surface water) drain. Most developments today usually have a separate surface water system for rainwater. Any connections to a private drain, as is proposed here by your new neighbour, will require building regulation approval from the council’s building control department. Any works affecting a public sewer would also need the permission of the council’s drainage section but this is unlikely to be an issue here.

As regards getting permission from the existing owners, yes, he would have to have your permission which generally should be forthcoming unless there is already an issue with the current private drain.

Reading your question, it would appear that the council has some issues if the planning file says the developer needs a completely separate drain. This will be picked up by the building control department (drainage division) when he approaches them prior to construction stage. Such issues might include inadequate gradient or pipe diameter, shallow invert level at start of drain run or a history of blockages.

But you are right to be concerned and I would watch that space and keep in touch with the drainage engineers in the council.

As regards responsibility for the maintenance of the drain, costs of repair would be shared equally by the 10 owners. If there is an issue with your existing private drain, you may want to discuss it with all parties including the council and the proposed number 11, and this might be an opportunity to relay the drain to serve houses 1-11 with the costs shared equally by the 11 owners? Just a thought.

Start by finding out the council’s reservation with the new house joining the existing line and take it from there. There could be opportunity here for all.

Pat McGovern is a chartered building surveyor and member of the Society of Chartered Surveyors Ireland, scsi.ie