# Forum Home Renovation Pools, Spa & Water Features  Back fill for pipework

## Wombat2

After 15 years ( and the prolonged dry) the mainly clay backfill to the pool return lines has shrunk/settled resulting in the pipe work - 1 - pulling one fitting from the wall and 2 -  (2 years later) spliting a join.  Having repaired it all what would be the best material to back fill to prevent further movement? 
I had thought of digging up all the pipes and using saddles to fasten to the concrete of the pool wall but the 2 meters I've dug up to do this repair the concrete below ground is rough as and would be difficult to get the pipes flat against it so I figure if I can back fill with something that won't move as much it should be OK. There will be grass over the top.

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## Haveago1

I'd reckon blue metal or gravel around the pipes to provide support but also a bit of movement as the ground around it (clay) expands and contracts with the varying moisture content.

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## Compleat Amateu

10mm gravel (not bigger!) is the recommended backfill for PVC, and I don't see your situation would be any different. 
10mm is small enough to "flow" around the pipework, and not sharp enough to cut it, form hard spots etc. 
I wouldn't attach the pipework to anything, I reckon you'l just create a hard spot.

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## Wombat2

> 10mm gravel (not bigger!) is the recommended backfill for PVC, and I don't see your situation would be any different. 
> 10mm is small enough to "flow" around the pipework, and not sharp enough to cut it, form hard spots etc. 
> I wouldn't attach the pipework to anything, I reckon you'l just create a hard spot.

  Sounds good - I haven't backfilled yet as I need to add about 12,000 lites of water to the pool to run the filter - and I needed to a) get a new filter and b) turn the dark green water clear (done)
In the mean time the repaired pipe work has slowly come back straight and realigned itself being 'out of the ground' and in the sun  :2thumbsup: so some of the pressure is off and i'll check for leaks before using gravel for back fill - thanks.

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## Yonnee

We're about to take delivery of a new swim spa, which will be in-ground. The manufacturers installer uses sand to backfill the entire pool below ground, so that will be good enough for me.

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