Often, yes, but only when the pipe manufacturer’s instructions or approved project specification allow it. Suitable graded aggregate can provide stable, even bedding that supports the pipe and maintains its required alignment and fall. Garden gravel, sharp stones and demolition rubble are not suitable substitutes.
When is gravel suitable?
Gravel or specified aggregate is appropriate when it can be placed and compacted to support the full pipe barrel without damaging or displacing it. Bedding fills voids and distributes loads; it is not simply there to improve water flow.
Gravel may be unsuitable when:
- it does not meet the pipe or project specification;
- the trench base is soft, disturbed or unstable;
- permeable material could redirect groundwater;
- sand or engineered support is specified; or
- compaction could move or damage the pipe.
Solid and perforated pipes serve different purposes, so their bedding requirements are not interchangeable. There is no universal aggregate size, bedding depth or pipe gradient.
What should you check?
Before selecting bedding, check:
- the pipe’s material, diameter and purpose;
- the manufacturer’s current installation instructions;
- the approved design or project specification;
- soil and groundwater conditions;
- expected traffic, building and ground loads; and
- whether separation fabric or ground improvement is specified.
Before excavating, obtain underground-service plans through Before You Dig Australia and use professional locating where needed, as plans may not show every service precisely. Do not enter an unsupported trench or continue if there is collapse, water-ingress or concealed-service risk. Follow current SafeWork NSW excavation guidance.
Sanitary drainage is regulated plumbing work in NSW. Check current NSW Fair Trading requirements and use a suitably licensed plumber where required. Our Sydney plumbing team can assess the pipe specification and site conditions if you are unsure.