Page 250 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

CHAPTER 5 COLD WATER SYSTEMS

INTRODUCTION

The supply of fresh, wholesome cold water to people’s homes is a basic human need. As a plumber, it is
your job to get the water from the main external stop valve to the taps so that it is clean and fit for human
consumption. Most people take for granted the supply of cold fresh water to their homes and few would
probably appreciate the degree of work necessary to provide this service.

In this chapter, we will look at the subject of water from the cloud to the tap, the cleaning process that makes it
fit for human consumption, the distribution of water and the systems that you will install. We will also explore the
regulations that govern our industry and the processes you will need to understand to enable you to work safely
and correctly on domestic cold water systems, from installation planning to testing, maintenance and fault finding.
By the end of this chapter, you will have knowledge and understanding of the following:
● the sources and properties of water
● the types of water supply to dwellings
● the treatment and distribution of water
● the sources of information relating to cold water systems
● the water service pipework to dwellings
● how to select cold water systems
● the system layout features of cold water systems fed from private water supplies
● the components used in boosted (pumped) cold water supply systems from private sources for single-
occupancy dwellings
● backflow protection
● how to install cold water systems and components
● how to carry out commissioning procedures
● how to replace or repair defective components
● how to decommission cold water systems.

1 SOURCES AND PROPERTIES OF

WATER

O The rainwater cycle

H H Water is a simple compound made up of two hydrogen atoms attached to a
single atom of oxygen, with the chemical symbol H O. Water is tasteless and
2
odourless and, in small quantities, it is colourless, while in large quantities it
p Figure 5.1 Water molecule possesses a light blue hue.
There is no new water on Earth – all water is about 4.2 billion years old, whether
it is sea water (saline), river or stream water, groundwater, fossilised water or
water from the polar ice caps.

238

9781510416482.indb 238 29/03/19 8:56 PM