Best Plumbing Services In Singapore. LJH Engineering is formed by a team of active PUB Licensed plumbers and Licensed Gas Service Workers (LGSW). We have more than 25 years of experience in the plumbing industry. We provide water tank cleaning services, repair and maintenance services, submission works, gas installation as well as plumbing and sanitary works. We are also the top specialists in pipe leaking detection and repair. We believe in trust and responsibility, to provide top quality and services to all our clients without fail. If you are looking for a trustable and transparent company, give us a call and our in-house Licensed Plumbers/LGSW will provide you the best solutions for your need.