Natural Resources Wales
Natural Resources Wales guidance says only clean water should enter surface-water drains.
Read the source →Wales, Wales
A useful Cardiff patio cleaning request records paving material, joint condition, staining and drainage. It should also settle whether cleaning alone is required or re-sanding, treatment or another optional stage should be priced separately.

The Cardiff brief
Focus on paving material, joint condition, staining and drainage. The key comparison is whether cleaning alone is required or re-sanding, treatment or another optional stage should be priced separately.
Evidence before method
These sources support the planning questions on this page. They do not prove that a particular method suits an unseen property.
Natural Resources Wales guidance says only clean water should enter surface-water drains.
Read the source →HSE guidance explains that biocidal products must be authorised for the intended use and used in line with their label.
Read the source →Questions for Cardiff
No. The paving, joints, coatings and condition should determine the method. Ask the provider to explain why the proposed process suits the photographed surface.
Washom does not publish an unsupported Cardiff average. Give each provider the same photographs, measurements, condition and access notes, then compare what each total includes.
No. Submit the patio cleaning brief and Washom will check for suitable independent-provider options. Availability depends on the job and location.
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Your next step
Share photographs, surface condition and access once. Washom will check suitable independent-provider options for this job.