11
Sewage disposal plants; Sewage treatment [purification] installations; Filters for wastewater; Purification installations for sewage; Waste water treatment tanks; Wastewater treatment tanks for industrial purposes
19
Building and construction materials and elements, not of metal; Structures and transportable buildings, not of metal; Stand tanks (Non-metallic -)
20
Containers, and closures and holders therefor, non-metallic; Storage tanks, not of metal or masonry; Liquid storage tanks [containers] made of non-metallic materials; Industrial water tanks, not of metal or masonry; Water tanks (Non-metallic -) [containers]; Water tanks of plastic for industrial purposes; Water tanks of plastic for agricultural purposes; Plastic water tanks; Reservoirs, not of metal nor of masonry
37
Building, construction and demolition; Providing information relating to the repair or maintenance of storage tanks; Providing information relating to storage tank cleaning services; Providing information relating to the repair or maintenance of water purifying apparatus; Installation of rainwater tanks; Installation of rainwater collection systems; Application of protective coatings to tank surfaces; Cleaning of storage tanks; Septic tank cleaning; Repair of water supply apparatus; Maintenance of water purifying apparatus; Maintenance and repair of storage tanks; Providing information relating to the repair or maintenance of vessels; Repair of biogas plants and machines
42
Science and technology services; Engineering services