Plumbing regulations - Wikipedia:
Much of the plumbing work in populated areas is regulated by government or quasi-government agencies due to the direct impact on the public's health, safety, and welfare. Plumbing installation and repair work on residences and other buildings generally must be done according to plumbing and building codes to protect the inhabitants of the buildings and to ensure safe, quality construction to future buyers. If permits are required for work, plumbing contractors typically secure them from the authorities on behalf of home or building owners.citation needed
In the United Kingdom the professional body is the Chartered Institute of Plumbing and Heating Engineering (educational charity status) and it is true that the trade still remains virtually ungoverned; there are no systems in place to monitor or control the activities of unqualified plumbers or those home owners who choose to undertake installation and maintenance works themselves, despite the health and safety issues which arise from such works when they are undertaken incorrectly; see Health Aspects of Plumbing (HAP) published jointly by the World Health Organization (WHO) and the World Plumbing Council (WPC). WPC has subsequently appointed a representative to the World Health Organization to take forward various projects related to Health Aspects of Plumbing.
In the United States, plumbing codes and licensing are generally controlled by state and local governments. At the national level, the Environmental Protection Agency has set guidelines about what constitutes lead-free plumbing fittings and pipes, in order to comply with the Safe Drinking Water Act.
Źródło: https://en.wikipedia.org/wiki/Plumbing#Regulation
Websites of companies hydraulic
Most companies now have a hydraulic websites. On these pages may refer potential customers to the qualifications held by employees and the scope of work performed by them. As a result, constantly gaining new customers who bestow greater trust those companies that can get to know. Other ways to promote the plumbers is displaying posters in the city and distributing leaflets advertising the company in which they work. On the Internet you can also find pages with the ranking of plumbers, where are published opinions on them. Therefore, the more plumbers are trying to do their job well, because they know that some negative reviews posted about them can effectively discourage the use of their services.
Replacing bathroom tiles
The services provided by a trusted plumber may include installation of bathroom tiles. Part plumbers standard also performs services tiling. The combination of exchange plates with a review of the hydraulic may be less expensive than using in a short time, the services of two experts. Replacement plates are combined, because the removal of old tiles, during which you can review the water supply, sewerage and carry out the necessary repair parts connections or clear partially clogged sewer pipes. This way you will not need to remove the newly installed bathroom tiles because of some failure of the hydraulic. This is all the more important that the available for sale tiles allow you to create the bathroom of real composition.