37 Construction, repair, installation and maintenance services for water, waste water, sewage, sludge, solid waste, rubbish, municipal waste and industrial waste treatment installations and plants, water treatment, water filtration and water purification plants and installations, commercial plants for the removal of rubbish, waste and sludge from water; construction, repair, installation and maintenance of water, waste water, sewage, sludge, solid waste, rubbish, municipal waste and industrial waste treatment installations and plants; construction, repair, installation and maintenance services, all relating to water treatment, water filtration and water purification plants and installations; construction, repair, installation and maintenance services, all relating to commercial plants for the removal of rubbish, waste and sludge from water; contract work, namely, plumbing, pipeline construction and maintenance, building and construction of water and sewage treatment works; consultancy and advisory services relating to construction, repair, installation and maintenance services for water, waste water, sewage, sludge, solid waste, rubbish, municipal waste and industrial waste treatment installations and plants, water treatment, water filtration and water purification plants and installations, commercial plants for the removal of rubbish, waste and sludge from water; consultancy and advisory services relating to construction, repair, installation and maintenance of water, waste water, sewage, sludge, solid waste, rubbish, municipal waste and industrial waste treatment installations and plants; consultancy and advisory services relating to construction, repair, installation and maintenance services, all relating to water treatment, water filtration and water purification plants and installations; consultancy and advisory services relating to construction, repair, installation and maintenance services, all relating to commercial plants for the removal of rubbish, waste and sludge from water; consultancy and advisory services relating to contract work, namely, plumbing, pipeline construction and maintenance, building and construction of water and sewage treatment works