Smelly surface gully problem

[scooby25]

Hello, I am a novice on drainage so apologies if my terminology is wrong! I have a smelly downpipe gully/drain. I have had a plumber and a specialist company in and who jetted (even though no blockages found) and cctv shows no damage to drains/pipes. It is better but not convinced the issue is resolved. Roof gutters are clear/clean. My foul and surface systems appear to be separate. All sinks and Wcs operate fine. I am at a loss to as why this 1 gully was so smelly. I have 3 Dow pipes on my property - was advised to replace the affected gully with one which is p-trapped - but as I understand it - if I have a twin system my rainwater drains do not need to be trapped? Any advice would be most welcome. Many thanks xx

[seanandruby]

Could be that not enough fall and water laying in the pipe becomes stagnent, could be trouble further down the line, or could be under the gully. You might be better having a direct down pipe into a rest bend. Is it an old system, metal down pipe, clay gully, or modern plastic? Photo's please. Where in the uk are you based?

[scooby25]

Hi, my house is 12 yrs old and it is all pvc pipework. I am up in Scotland. The drain is question is a 90 degree bend with a rodding access point and is at rear of the property. My drainage system runs from the rear to the front of the property. Have been in the house since sept last year and have not experienced 'this until about 3 wks ago. Xxx

[seanandruby]

So the down pipe goes straight into the 90 not an hopper with grating? As i said in last post the problem could be further down the line. If it persists you could try a p trap to stop the smell.
If the drainage guys couldn't find a problem it is difficult for us, it is guess work. Maybe wait a monitor it for a while.

[scooby25]

Apologies, I have a hopper and the rainwater pours into the hopper from the downpipe and the drain itself is 90 degrees with a rodding access point. Yes I will monitor for a while and see what happens. Just concerned as there doesn't appear to be an obvious cause!!! Just worried it will lead to a larger problem!! Many thanks for replying. Xx

[Tony McC]

A trapped gully is the simplest and cheapest potential 'fix'. It wil prevent any sewer gases venting through.

I wonder if the very dry spell we've been allegedly enjoying copuld be uinvolved? Much less surface water to flush away anything dodgy resting in the system (even if it's 400 metres from you) and sewer walls/benching/side outlets that are normally submerged being left high and dry could cause a stench which is finding its way through the system and escaping through your un-trapped fitting.

[scooby25]

Hello, thank you for taking the time to reply and offer advice. The thing is I am confused as to why my surface/downspout drains/gullys would smell of sewage gas if they are supposed to be separate from my foul/waste drains? ???? I have 4 manholes or inspection chambers in my front garden. 2 for the foul and 2 for surface water as I understand it. Am lost - I am trying to understand drainage but am struggling!

[seanandruby]

Well it could all fall into an old dual system. Also it's not unknown for someone to do a bodge and pipe the surface water into a foul run, not saying that is the case but to smell of foul is not right. As already mentioned you could use a trapped gully. Also have you read the index on drainage ?

[scooby25]

Hello, yes i have had a look at index on drainage, and numerous other searches on drainage. Got my layout from the local authority too. I think I am maybe reading to much and confusing myself in the process!!! If only I could definitely identify the problem in order to get it fixed!

[seanandruby]

I think the drain guys would of flagged up any serious problem scooby. I'd go for gully and then forget it or it'll drive you bonkers :;):

[scooby25]

Lol yes . I must admit I am going slightly mad!!!
:p

[scooby25]

Hello everyone, why do I gave smelly surface water drains. The drains are NOT trapped as my foul lines are separate. My neighbours drains are the same as mine! But I have smelly ones. Each home has separate drainage feeding into public drains. Have been advised by drain company to install trapped drains. But that is not giving me the reason why for the last month they smell! CCTV done and no blockages or damaged pipes found. This is driving he mad!!!

[seanandruby]

For us Scooby it is only guesswork. Are you up line, down line on the drainage? Are you sure it is coming up the pipe and not the surrounding area? Has the drain guys confirmed the foul goes to fould and storm to storm, it's not unknown for some one to f%#$ up and connect
Into wrong line. What ground is your place built on I E contaminated? Wish could do and tell you more but it's difficult without having a sniff :;):

[scooby25]

Lol - u don't want to sniff! I am unsure where to find out the info you are rightly asking. I would not wish to have the drain company I used back. They did say my foul and surface are separate and it would seem correct judging my the number of inspection chambers in my front garden. My Local Authority did send me the drainage layout for my housing scheme and it would seem to confirm separate systems. How can I tell if I am up live or down line? Nit sure what questions I should be asking? Xxx

[seanandruby]

Smelt a lot worse when i'm down a deep manhole, or shaft. Does it smell like sewerage, rotten eggs ( hydrogen sulfide ) I'm just clutching at straws really. I think you should put in the gullies and see how it goes. I just thought if you are end of line and the problem was up line that would be the reason only you get the smell, if it was further down then others would be suffering to. It is certainly an enigma.