plumbing; installation of plumbing; maintenance of plumbing; plumbing services; repair of plumbing; plumbing installation, maintenance and repair; installation of plumbing systems; advisory services relating to the installation of plumbing; plumbing maintenance advisory services; advisory services relating to the maintenance of plumbing; plumbing repair advisory services; plumbing installation advisory services; advisory services relating to the repair of plumbing; installation, maintenance and repair of water supply apparatus; installation of equipment and apparatus for gas and water supply; repair or maintenance of water purifying apparatus; repair of gas and water installations; toilet [water-closet] installation and repair; installation and repair of toilets [water-closets]; installation of apparatus for sanitation; maintenance and repair services of public utilities in buildings; installation of pipes; repair or maintenance of gas water heaters; maintenance of bathtubs; installation and repair of water closets; shower installation and repair