Building near a storm drain

8 Mar 2012
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United Kingdom
Builders are 2 weeks away from starting the foundations for my extension. On Saturday I got a letter from Thames Water saying that they thought I was about to build within 3m of a minor public sewer and should submit plans to get their agreement. Me, my builder and architect have looked and there are no sewers at the back of the house where we're going to build - they all go out the front. What there is is a storm drain (with manhole cover marked 'Storm') which we'll be within a 1m of. Have tried to contact Thames Water and they are so busy they can't even speak to me for 10 days to discuss whether they've made a mistake or know something no else does. Have contacted local BCO who has checked sewer plans and said nothing showing at back of house. Reason for the post is that she then said that she believed that recent changes to regulations now meant that if a storm drain is either built over or within 3m, it gets re-classified as a 'public sewer' and needs permission from Thames Water. Is that true? Sounds odd to me. Can anyone help please?
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The legal situation regarding sewers changed last year, B.C.O. is getting confused I think.

It may not serve your property, but if the sewer carries a watercourse or drains a nearby area it'll already be a public sewer. You have a manhole cover, fairly safe to say there's a sewer there. It'll need some type of protection if you are building nearby, what protection will depend on size, depth and construction of the sewer. Thames Water will advise, it's their asset.
Thanks for the link Hugh. Since the drain is on my propoerty I'm still not sure if its mine or Thames Waters. As you say, they'll be able to advise but their current response time is ridiculously slow - they said its because they'd grossly underestimated the extra work of taking on all these new drains. Can you specifically clarify that a storm drain can be a public sewer as defined by the Water Board? thanks
Chances are its Thames pipe, but is on your property. There may (should?) be an easement in the property deeds to allow for its presence.

Yes, storm drains (if carrying water other than water specifically from a highway, in which case it may be the highway authorities responsibility), are public sewers. A watercourse can also be classed as a public sewer if it carries stormwater.
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Ignore the "storm drain" writing, that just identifies what it is carrying

Any section of drain serving more than one property is now a public sewer for all intents, and the responsibility of the local water authority

But the drain could have already been a public sewer anyway

Your designer should have sorted this all out when he did the drawings
Hmmm, unfortunately the designer didn't take account of any requirements for Water Authority approvals.
Thanks both of you for your replies. I'll post back with more info as it emerges in the hope that this may help someone else in the future.
Hi, I believe there is a question over what is legally enforceable.

Section H.4 (para0.3)of the building regs: Drainage and Waste Disposal refers to 'Building over sewers' and defines Public Sewers as those shown on the 'map of sewers'. This map must be provided by law by the water authority and available for inspection by landowners (Either call up Thames Water ....who will answer the phone eventually ....or your BCO.).

If no public sewer shows up on the map (and it's likely it won't as mapping all those new private sewers adopted since Oct 2011 is a massive undertaking) then you could argue that you checked the statutory maps as directed, couldn't find any reference to a public sewer on your land and are therefore complying fully as far as you are aware. (Be prepared for a possible tussle though!).

I advise clients to make the application to build over anyway as they don't have to pay the fee until it has been confirmed that they are indeed building near or over a sewer. Thames Water should reply within 14 days.

PS: A BCO I talked to implied that the water authorities possibly had their eye on the £343 fee that accompanies applications to build over class 1 public sewers and had been sending out forms regardless.

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