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 strictly regulated under NSW Fair Trading and Building Commission NSW rules, requiring work to be supervised under Contractor Licence 305428C. Installations must adhere to the national plumbing and drainage standard AS/NZS 3500.2 (which sets strict rules for trench bedding materials, pipe side-clearances, and minimum cover to ensure drains do not crack or shear under surface loads).
Fixed Today is the reliable plumbing team Sydney homeowners and property managers have trusted and returned to repeatedly for over 15 years. Before heading out, our dispatch team asks a few practical screening questions about your site conditions—such as whether you have reactive clay, sandy loam, or sandstone bedrock, and whether the trench crosses driveways or gardens—so our utility vehicle arrives with the right trenching, bed-preparation, and laser-levelling gear. Our licensed Sydney drainage plumbers walk you through a clear task breakdown of the recommended bedding and pipe-laying steps, delivering transparent upfront pricing with a $0 call-out on approved work.