Monday, 31 March 2014

Basic requirements for the installation of drainage systems

Drainage is listed as a controlled service/fitting. Controlled services and fittings are those covered by Parts G, H, J, L or P in the government Building Regulations. These include:
  • Water supplies 
  • Toilets 
  • Urinals 
  • Hand basins 
  • All sanitary fittings 
  • Drainage 
  • Water disposal systems 
  • Fixed fuel burning heating appliances 
  • Electrical installations 
What this means is that when any of these items are installed, they must be installed in accordance with the requirements of the relevant Building Regulations.

If any work carried out does not meet the minimum requirements stated within the Building Regulations, local authorities will serve a notice, ordering any defects present to be remedied. In some cases a local authority will carry out the work in default and then recover the cost.

Overview of Requirements for Drainage

The regulations detail a number of requirements, please see the following list for an overview of those relevant to plumbing drainage;
  • No material may be used where there is any possibility that contamination of water could occur due to the material. 
  • Water fittings must be protected from erosion and be of suitable strength and thickness 
  • Water fittings must be water tight and constructed to prevent ingress by contaminants/inhibit damage by freezing as well as being adequately supported. 
  • They must be capable of withstanding any internal water pressure not less than 1½ times the maximum pressure. 
  • A water fitting must not be likely to have a detrimental affect on quality/pressure of water 
  • Water fittings must not be embedded in any wall or concrete floor. Where laid below ground level the cover must be sufficient to prevent water freezing. 
  • There is a restriction on concealed water fittings. 
  • Cold water must be kept in such a way that it is not likely to be warmed above 25ºC. 
  • A stop valve must be provided. 
  • The supply system must be capable of being drained down. 
  • The rain water system must be tested, flushed and where necessary disinfected before it is first used. 
  • Any water fittings must bae identified so as to distinguish them from water supply pipes. 
  • There must be adequate devices to prevent back flow. 
  • The pipes supplying water to a storage system must be fitted with a valve to shut of the inflow or a system must be installed so as to minimise the risk and contamination of a store of water and they must be designed to allow free circulation. 
  • Appropriate feed pipes must be provided for water systems. 
  • There must be a temperature device to prevent water heating above 100ºC. 
  • Provision must be made for expansion valves etc in water systems. 
  • A w.c. must be supplied with a water flushing system, by a single flush. 
  • There must be at least one tap conveniently situated for drinking water. 
  • Every bath, wash hand basin, sink or similar must be provided with a watertight plug, subject to certain specified exceptions. 

Foul Drainage

Document H1 (page 17) details the requirements for foul drainage, with information on; bedding and backfilling, rigid pipes, and flexible pipes. This document explains what rate of bedding factor is needed for rigid pipes, flexible pipes and variations for different types of ground. Also detailed are types of appropriate fill material and to what depth should be filled.

Drainage Pipework Requirements

There is a detailed section on pipes including; clayware pipes, concrete pipes, and thermoplastics.

Detailing; the measurements dependant on the nominal size (width of the pipe) laid in fields, laid in light roads, and laid in main roads.

Additionally, H1 details what pipe protection is needed for all kinds of pipes and at all depths. Access points are of course vital when installing drainage, such as; rodding eyes, manholes, inspection chambers, and access fittings, there is a guide to; depth, length and thickness of pipe.