Forum Topic

Condensing steam/water from boilers

Way off the main topic but perhaps someone on here can advise.Is it OK for the condensing steam/water from domestic boilers to run into the Clean Water (rainwater from roads and roofs) drainage system that goes, untreated back into the river?    Or by law, is it deemed as Dirty Water and has to run into the Foul Water (sewage, bath/shower, kitchen sink, washing machine, dishwasher) drainage system that runs off to be treated at sewage works before being released back into our rivers and reservoirs?    Can't find out from Thames Water.   Thanks.

Jennifer Selig ● 2417d8 Comments

I recently had a new boiler and the pipe goes into the drain from roof gutter.

Janice Evans ● 2417d

In my Victorian house, the rainwater and foul water run into a common sewer, as, ultimately, will yours. Nothing about which to worry.

N V Brooks ● 2417d

Apparently it's only OK to pass the condensate into the rainwater drain if that passes to a combined foul and rainwater sewage system, which I believe ours does.  Certainly Bazalgette's London system is a combined system, and I think our West Middlesex system is also.There are problems with using rainwater drainage for boiler condensate if the connection is not protected against freezing in very cold weather, and for that reason is usually discouraged. There's a guide about this from the Heating and Hotwater Industry Council, available at https://hhic.org.uk/uploads/5BD6D5A19764A.pdf.  See particularly page 13, or search for "permissible".

Richard Jennings ● 2417d

Brit.Gas put external pipe, have to insulate it then.

Janice Evans ● 2417d

They may have use insulated pipe, just reading up other info on it.

Janice Evans ● 2417d

Thanks everyone.  Firstly, where I live, we have two distinct drainage systems.  The rainwater, Clean Water drain runs directly into the river not into the Foul water sewage system.    Secondly, many of the condensation pipes protrude from the outside house-wall and do not connect to any pipe at all, others are connected to a pipe that runs down into the Clean Water drainage system.  Have not noticed any lagging to protect against freezing either.  Will read up on the link given by Richard here.

Jennifer Selig ● 2417d

Do you mean condensation from the 'plume' or the condensate pipe which leaves the boiler?If the first, then no regulations, it is vapour.If the second, then the route of the pipe is governed by the building regulations because the liquid in it (condensate) is mildly acidic - so the pipes that it discharges into have to be resistant to this until it hits a larger body of water and is diluted.Externally it should be insulated as if it freezes your boiler will back-up.It should not discharge into concrete etc as it will gradually (it is a slow effect) eat away at these.But eventual discharge into the water course is fine.HTH

James Holmes-Siedle ● 2417d

Thank you both Richard J and you James - I have no idea but have passed the info onto the relevant people.  Don't think I'm affected.  Suppose no-one can get workmen in anyway for the moment.  Say in and stay safe.

Jennifer Selig ● 2417d