# Forum Home Renovation Plumbing  pool backwash to sewer connection

## jack620

I've been discharging my pool backwash water onto the lawn. Now the lawn is stuffed so I want to hook up my backwash outlet to the sewer.  
I've checked AS3500 and it appears that the only approved method of connecting pool waste to the sewer is via a branch off the gully riser (clause 10.9, fig 10.2).  This is a real pain, because the gully is a long way from the filter. 
Ideally I'd like to run a PN50 pipe from the filter, through the wall of the house and connect it into the sewer pipe that runs under the floor.  Is there any way I can do this and still comply with AS3500?   
Rgds,
Jack

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## clear

you have to do it exactly as you read in as3500. the reason you do this is so it can discharge with a registered air gap of 75mm. this is to prevent any sewer back up entering your pool as a result of a blockage in either your house sewer or the sewer mains in the area. you wont require any fall to the gully as it will be a charged line constantly holding water. hope this helps

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## wonderplumb

It actually has to come out of the ground then discharge over the top of the gully, so you will have a riser then two bends to make it look back down over the gully.

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## jack620

Thanks Fellas,
I was afraid you'd say that!  
As a matter of interest, are indoor pools plumbed the same way? 
There's a sewer IO not far from the filter.  It's the one right next to the sewer pit.  I think I'll just remove the cap and drop a flexible hose in to it whenever I backwash.   Not ideal, but better than pumping it into the stormwater I guess.

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## wonderplumb

I can't see why an indoor pool would be any different.

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## Gaza

> Thanks Fellas,
> I was afraid you'd say that!  
> As a matter of interest, are indoor pools plumbed the same way? 
> There's a sewer IO not far from the filter. It's the one right next to the sewer pit. I think I'll just remove the cap and drop a flexible hose in to it whenever I backwash. Not ideal, but better than pumping it into the stormwater I guess.

  how often do you backwash? 
mine's only done once a year if lucky.

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## jack620

I backwash when the filter pressure gauge has increased by 10psi since the last backwash.  It varies with the season, but it's a lot more frequent than once a year!  :Smilie:

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## jack620

After investigating the options, I've decided to do it properly as per AS3500.  Fig 10.2 makes it pretty clear what's required.  I have one question I hope someone can help me with.  Once I've dug out around the existing gulley pipe what's the easiest way to cut the pipe to allow fitting of the 45 degree junction?  I can't see myself being able to use a handsaw unless I dig a huge hole.  Is there a trick?  :Confused:

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## Bedford

> Is there a trick?

  If it's PVC you can secure a 100mm cut off wheel onto a bolt with two nuts, fitted into the chuck of a drill, and saw it off from inside the pipe.

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## jack620

Thanks Bedford,
It is PVC.  The cut will be a fair way into the pipe (about 500mm I'm guessing) so I suppose I'll have to do a rough cut from the outside first and then tidy it up using your method.

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## Bedford

Set the cut off wheel up on a piece of all thread to get enough length.

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## clear

if you dig enough around it just use a little grinder to cut it off.

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## jack620

thanks for the tips!

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## letmein

Can someone post Fig 10.2 from Section 10.9 of AS 3500.2.2  or post a link to a site that has it?

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## jack620

I'm away for few days so don't have access.  
Bedford,  I tried your trick with the threaded rod and grinding disc.  It was slow but it worked beautifully.  Heavy gloves advisable to save the skin and to catch the rod when it works loose from the chuck.

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