What are the requirements for the Overflow Relief Gully?

[4sfed]

We have recently finished a bathroom renovation and we are now moving on to landscaping the back yard. As part of the bathroom reno, there was a new Overflow Relief Gully (i think thats right?) installed which sits right in the spot we were looking at installing a bench seat, so i have a couple of questions on if it is possible for the position of the above ground outlet to be moved. See attached picture.

The green line is floor level, and i understand the outlet needs to be 150mm below this - no problems there.
Are there any specific rules around if i can have bends in the above ground portion of the pipe? I see 2 possible solutions to our issue.

1. Red line - simply put a 90 degree bend and move it out of the way, with the end of the pipe outlet being horizontal.
2. Blue Line - put a "dog leg" in it and move the outlet to a more convenient position to let the bench seat be constructed.

Are either of these 2 options "allowed"? I couldnt see any regulations that stated there must be direct (ie: vertical) access to the pipe incase of blockage or whatever. Anything else that i am missing that may cause either of these options to not be viable?

We have attempted to reach out to the plumber that did the initial work to ask this question, but it was a good 3+ years ago and he seems to be uncontactable. Once we know what is or isnt allowed we can make the design changes to suit, then get a plumber in to do the work. 

Thanks in advance.

[MitchellMc]

Welcome to the Bunnings Workshop community @4sfed. It's fantastic to have you join us, and many thanks for your question about overflow relief gullies.

Overflow relief gullies are designed like this to offer the most straightforward escape for sewage in case of blockage. There might not be any particular rules regarding a horizontal exit, but the more complicated you make it for the sewage to escape, the less effective the relief is. If you are going to have a plumber do the work, then it will be up to them on what they sign off on. Whether there is a rule or not, a plumber might not be willing to make adjustments purely to accommodate a bench. It's likely best to give a few plumbers a call and get an idea of what would work.

Is there any way you could adjust your plans for the bench to suit the outlet? If you were to show our helpful members a sketch of what you intend to build, perhaps they could come up with some neat solutions.

Please let me know if you have any questions.

Mitchell

[4sfed]

Thanks Mitchell! I completely understand your reasoning and thats what prompted me to ask the question. It makes sense that the easiest path out is the best.

We are in a position to make changes to our plans if needed, but we dont know what to change until we know the overflow requirements, and until we know the changes needed to the overflow we are finding it difficult to engage a plumber, so its a bit of chicken and egg here.

Here is another (poorly) sketched diagram. The yellow is roughly the proposed built in seating area which goes directly over the outlet.

Our hope was to be able to move the outlet to the side as per the red line, that would make the most sense in the grand scheme of things. We could use 2x45 degree bends to eliminate any tight 90 degree corners.

Alternatively, we could push the seat out by say 200mm off the way to allow a garden bed and have the pipe vent in that area (pink line). Thats less than ideal as it makes utilizing the wood cladding as a backrest not practical.

[MitchellMc]

Could you build the seating over the outlet @4sfed? You'd only need to design in some type of access panel. Perhaps the seat section could be on hinges, so it lifts when access is required. 

Mitchell

[4sfed]

Yes this is under consideration as an option. The top of the bench will be paved to match the surrounds (then cushions ontop of that when in use), so we just need to consider the weight of the pavers when providing access as they are very heavy and almost a 2 man job to lift each one.

Thanks again for your input, we will play with a few ideas and see what works best.

[MikeTNZ]

Hi @4sfed,

You need to engage the services of a registered drain-layer with this.

As far as I'm aware, only craftsmen plumbers/drain-layers are allowed to touch sewerage lines, for fear of them being blocked by putting elbows and what-not on them.

At the same time, the drain-layer may be able to relocate it for you, so that it is not in your way.

Let us know how you get on.

Cheers,

Mike T.

[EricL]

Hello @4sfed

It's great that you've received excellent recommendations from @MitchellMc and @MikeTNZ. I'm in agreement with the recommendation of getting a registered plumber to move the overflow. I suggest having a quick look at the rules and regulations for moving an overflow relief gully in your area. Having the overflow moved by a registered plumber will guarantee that the work has been done to code.

If you need further assistance, please let us know.

Eric   

[4sfed]

Thanks everyone - yes once we work out what is and isnt allowed, and how we can change our plans to accomodate we will certainly get the pros in to do it. Its been tough to find anybody that we can simply ask the question of to allow us to think of the best solution with everything considered, redesign as needed, then get the work done. We will keep at it though.

[Jason]

No worries @4sfed, please feel free to post anytime you need a hand.

Jason