The direct answer
Start with the complete system, not one product or headline rate.
What changes the cost of investigation, excavation, storage, pipework and reinstatement—and why a crate-only price can be misleading. A dependable plan connects the site evidence, approvals, access, installation sequence and finished reinstatement.
Cost is shaped by the whole water path
A quote needs the connected roof or paving area, proposed position, ground evidence, pipe route, access, depth and finished surface. Storage crates can be a small part of the real job.
Investigation can save a failed installation
Checking the existing inlet, silt, ground recovery and available outfall avoids replacing a system that is not the true cause—or installing a new soakaway where infiltration is unsuitable.
Compare inclusions line by line
Look for excavation depth, spoil removal, capacity, geotextile, pipework, silt control, inspection access, testing and reinstatement. A cheaper headline may omit several of these.
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