1. Cold Water
Understand and apply domestic cold water system installation and maintenance techniques

2. Cold water systems Module 1
Learning outcome
After this session you should know and be able to describe the cold water supply route to dwellings

3. Cold water systems What we will cover Rainwater cycle
Water supply sources
Main type of water supply to dwellings
Water treatment
Uses of water supplied to dwellings

4. Rainwater cycle

5. The water cycle, also known as the 
-hydrologic cycle 
-H2O cycle
TASK
Describes the movement of water on, above and below the surface of the earth

6. The earth contains about 326 million cubic miles of water
70% of the earths surface is covered in water
The sea holds about 95% of all the water on earth

7.  The physical processes are
-evaporation
-condensation
-precipitation
-infiltration
-runoff
-subsurface flow
The water goes through different phases:
liquid, solid, and gas

8. Water supply sources Surface sources -Lakes -Reservoirs
-Rivers and streams
Underground sources
-Deep and shallow wells
-Artesian wells
-Bore holes
-Springs

9. It is estimated that every person in Britain uses 150 litres of water per day.
Population figures for mid 2012 revealed that there is now 63,700,000 people living in the United Kingdom.
By doing a simple maths calculation we can see this country uses a staggering, 9,555,000,000 litres of water per day.

10. The Primary source of water in this country is Rain.
The Average annual rainfall in this country varies between 750 and 1000 millimetres, 30 – 40 inches ( accessed 19/02/2010)
In some parts of the world, countries with very low rainfall have turned to desalination of seawater to provide potable water.
Potable - fit to drink.

11. Rainwater falls into streams and rivers, and eventually ends up in lakes and reservoirs.
Countries need to manage or harvest this rainwater, so that we have something to drink.
So a lot of rivers have had a dam constructed on it to be able to provide us with adequate supplies of drinking water.
A good example of this can be seen at the Brennig and Alwyn Reservoirs. (

12. Surface sources
Lakes and reservoirs
Water is stored by water companies either in its untreated state in impounding reservoirs or lakes, or as wholesome water in service reservoirs

13. Water companies usually aim to store enough drinking water in their service reservoirs in case of emergencies
This is to maintain a supply for about 24 hours
This safeguards against failure of pumps or mains and allows time to repair any faults before supplies run out

14. Rivers and streams
A river is defined as a large natural stream of water emptying into an ocean, lake, or other body of water and usually fed along its course by converging tributaries

15. Water from rivers varies in quality depending on the location
Water from upland and moorland rivers and tributaries tends to be relatively wholesome
Downstream it becomes polluted by natural drainage from agricultural land, industrial premises and road surface run off

16. Bore holes Used to reach the aquifers that are below the impermeable rock layer

17. Springs
The quality of spring water varies depending upon the route that the water has taken from underground to the surface
If it has traveled for a long distance through rock formations, it will probably be free from contamination

19. Main type of water supply to dwellings
Supply from water undertakers main
Supply from a private source

20. Supply from a private source
In general terms a private water supply is any water supply which is not provided by a water company
It is not a "mains" supply
About 1% of the population of England and Wales have private water supplies to their homes

21. Most private supplies are situated in the more remote, rural parts of the country
The source of the supply may be a well, borehole, spring, stream, river, lake or pond
The supply may serve just one property or several properties through a network of pipes

22. The Private water regulations 2009 came in to force on 1 January 2010

23. Supply from water undertakers main
Gives guidance on the water quality aspects of common carriage in relation to public supplies

24. The Water Undertakers (Information) Direction 2009
States that the definition of a water undertaker is a company that
-Supplies water to the public

25. Water Companies are obliged to demonstrate "due diligence" at every stage of the provision of drinking water from…
Abstraction
Treatment and storage
Delivery to the customer's tap
Water Industry Act 1991 makes it a criminal offence to supply water which is unfit for human consumption

26. Wholesomeness is the term used by the DWI to define compliance with the regulations.
The definition of wholesomeness is water that is supplied to the public for
Consumption
Washing
Food preparation

27. Water Treatment

28. Water treatment
It’s the responsibility of the water companies to ensure water is wholesome (fit for consumption, washing and food preparation)
All water must therefore be treated before it is put into the supply distribution system

29. How they treat it will depend on its source and what impurities are contained within it
Some impurities are actually essential to our health and will be retained, others are harmful and must be removed during treatment

31. The cheapest and easiest way to distribute water is by gravity.
The efficiency of a gravity fed system is dependent on the number of properties and the volume of water being supplied.
This in turn is dependent on
Pressure of water in the mains

32. Size of the main
Demand upon the main
Pressure of water is often referred to as head.
Head – The height to which water in the main would rise in a vertical pipe.
A suitable pressure, or a sufficient head of water, is considered to be 30 to 70m.

33. This will allow sufficient pressure for all properties.
It is also acceptable for the Local Fire Brigade.
Pipework would also be within normal strength requirements
Transmission noise would also be limited to an acceptable level.

34. Water Pressure
The Higher a column or head of water, the more pressure is exerted at its lowest point.
To try and explain this a little clearer we can use simple calculations.
For example if we had a container that was 1m³ it would weigh 1000kg or 1 tonne.

35. Water Pressure
The force or pressure that this would exert could be calculated using the formula
Force = Kg mass x acceleration due to gravity.
Acceleration due to gravity is 9.81m/s²
Force = 1000Kg x 9.81m/s²
Force = 9810 Newtons or 9.81 kn/m²

36. So if a container 1 metre high exerts a pressure of 9.81 kn/m²

37. Then a container 5 metres high would exert 5 times the amount of pressure.
5 x 9.81 = kn/m2

38. ? What we have just calculated is known as the Intensity of Pressure.
We can now use this Intensity of pressure to calculate the head of water in a given system.
For example. If the mains water pressure is 450 kn/m², calculate the head of water. ?

39. The formula we need for this is
Intensity of pressure = Head x 9.81
By transposing the formula to find the Head
Head = 450 ÷ 9.81
Head of water = 45.87m
In other words the water would rise metres in a vertical pipe.

40. Water Distribution
Water is distributed from water tanks / service reservoirs by means of a water mains.
Trunk mains are used to carry large volumes of water into built up areas.
These are then reduced into street mains and finally a sub mains before entering a building.

41. Typical water distribution to buildings

42. Uses for water
Wholesome water is used around domestic properties for:-
Drinking
Food preparation
Washing

43. Drinking and food preparation requirements
Water for consumption and food preparation is supplied via the kitchen sink tap
This draw off point is taken straight off the rising main just after it enters the building
This ensures that only wholesome water is used for drinking and food preparation

44. Washing requirements
This can also be drawn straight from the rising main the same as the kitchen tap
or can be supplied from a cold water storage cistern (CWSC) sited elsewhere within the building

45. Greywater Typically defined as being water collected from the:- Bath
Shower
Wash hand basin (Be careful of toothpaste it can clog some filters)

46. The ideal situation for Greywater is in living accommodation where sufficient amounts are generated daily for reuse in
- toilets
Greywater recycling represents a major contribution to ecological sustainability

47. Rainwater harvesting
Typically defined as being water collected from roofs via traditional guttering & down pipes to an underground storage tank

50. Delivered on demand by an in-tank submersible pump direct to
- Toilets (biggest user of water in the property)
- Washing machines
- Outside tap (can be used for vehicle washing and garden watering
More than 50% of mains water can be substituted by rainwater

51. Cold water systems Module 2
Learning outcome
After this session you should know and be able to describe the cold water systems and their layout requirements

52. What we will cover Water main to internal stop tap
Types of cold water system
Selecting a cold water system
Cold water supply pipe sizes

53. Water main to external stop tap
Water supply installations in England and Wales were controlled by the local water bylaws and were replaced with the water regulations on the 1st July 1999
Scotland and Ireland have their own separate arrangements

54. Water suppliers and water regulations
Obtaining water for human consumption to the consumer is the job of the of the water suppliers
The water supply (water Fittings) regulation 1999 say they must provide wholesome water to the dwellings at temperature no warmer than 25 °C

55. Water mains are constructed of asbestos cement, steel, PVC or cast iron
Water supply companies are responsible for making the connection to the water main in the street

56. A valve called a Ferrule is used to connect to the water main
This can be done live under mains water pressure using specialist tools and equipment

58. Completed connection

59. Communication pipe
The pipe that connects to the ferrule is called the communication pipe
This pipe would be serviced and maintained by the water supply company
This pipe runs up to the boundary and could include the external stop tap

60. The main external stop tap can be used to isolate the water supply to a single property or multiple properties
Properties that share a common external stop tap will be older properties such as Victorian terraces

61. Modern external stop tap and water meter chamber

62. Meter types
Internal External

63. The Groundbreaker is an above ground water meter box with 25 mm inlet/outlet connections
Can accommodate water meter and external stop valves
WRAS approved

64. Water meter box
Groundbreaker

65. Service pipe
To protect against frost damage, mains and service pipes should be at least 750 mm beneath the surface of the ground
The maximum depth of cover should not exceed 1350mm, this is to allow for ease of access

66. Blue MDPE is the modern choice for service pipework
Metal pipes should be protected against possible corrosion from the soil, particularly acidic soils
This can be done by:
- use of plastic sheathed pipe
- wrapping the pipe with an anti corrosive tape
- installing the pipe inside a duct

67. Where there is a risk of contamination the pipe should be relocated or replaced with barrier pipe

68. The minimum size allowed for a cold water service pipe to a dwelling is 15 mm
Water supply companies will recommend 25mm service pipe to help cope with higher demand from modern appliances
Water companies aim to supply water at a minimum pressure of 1bar and at a flow rate of at least 20litres per minute

69. Supply pipes entering buildings
All pipes that enter a building should be ducted
The water regulations and British standard 6700 give guidance on these requirements

70. Pipes that enter a buildings more then 750mm from the out side wall only need the ends of the ducts sealing
This helps to prevents ingress of gases like radon
It also helps to stop bugs getting in to the property via the duct

71. If the duct is less then 750mm from the outside wall the duct requires insulating
This helps slow down the effects of freezing on the pipe

72. If the pipe passes through a suspended floor it will require insulation no matter how far it is from the outside wall
This is because of air vents that are required to ventilate under suspended timber floors
These can create drafts which can cause pipes to freeze

74. On entry in to a building the water supply pipe requires an internal stop tap and drain down valve
This is a requirement of the Water Regulations

75. The Water Regulations specify:-
Stop valve should be easily accessible installed at 150mm above floor level

76. Use as a blank handout and let students fill out all details and dimensions

77. Types of cold water system
They are two types of cold water system that can be used in a dwelling
Direct
Indirect

78. Selection of the type of system depends on various factors
Water pressure to the property (Bar)
Water flow rate to the property (Litres per second)

79. If the incoming water supply pressure and flow rates are good then a direct system could be the best option
With the higher pressure and flow rate all the draw off points within the building could be met by a direct system

80. Other factors to consider would be if the property has an history of bursts on the mains supply
This could create a nuisance factor if a direct system was selected
Appliances/fittings installed on existing properties might not perform correctly if a change of system was put in place

81. Direct system

82. Direct system The advantages Less pipework is required
Storage cistern is smaller (110 litres minimum) BS6700 recommends that the cistern be at least the same size as the hot water storage cylinder
Drinking water is available from all draw-off points
Less risk of frost damage due to less pipework

83. Direct system Disadvantages Higher pressure can make the system noisy
No reserve of cold water if the mains or service supply is interrupted
More wear and tear on taps and valves due to higher pressure
Higher demand on the mains at peak periods

84. Direct system
Direct system are the most commonly installed type of cold water system
Direct systems usually supply water to instantaneous water heaters and combination boilers

85. Combination boilers
Advantages with a combination boiler is that all the properties needs can be met with a single boiler installation
Central heating
Direct cold water
Direct hot water

86. Usually combination boilers are directly fed from the mains and the heating systems are sealed and pressurised
This offers the advantage of not having any cisterns in the loft space which reduces the risk of freezing and keeps installation cost down

87. Indirect system

88. Indirect system
Draw-off points (Baths, Basins, W/C’s) in an indirect system are fed indirectly from the cold water storage cistern
One outlet usually the kitchen sink tap is fed directly from the supply pipe
Indirect system are designed to be installed in low water pressure areas

89. Indirect system Advantages
Indirect systems offer a reserve of stored water in the event of mains interruption
Reduced risk of system noise due to lower pressures
Lower pressures at draw off points means less servicing required

90. Indirect system Disadvantages Increased risk of frost damage
Space occupied by the larger cold water storage cistern (CWSC) (230 litre minimum) minimum size required as laid down in BS6700
Additional cost of the bigger storage cistern and extra pipework

91. Pipe sizes used in cold water systems
Supply pipe
Distributing pipe
Service pipe

92. Supply pipe
External supply pipes into a building are recommended at minimum of 15mm
Water companies recommend 25mm MDPE external supplies in order to cope with demand from modern appliances

93. Distributing pipes
It is recommended pipes from storage cisterns are sized for flow rate due to lack of pressure within these types of systems
22mm would be used where water is distributed to appliance outlets
22mm up to baths
22mm reduced to 15mm to basins and W/C’s

94. Service pipes
Direct systems can use 15mm pipes to appliance outlets due to the higher pressure offered from the mains
Further guidance can be found from
Pipe sizing for hot and cold water part one – basic principles

95. Task Draw a direct and indirect cold water system
Name all the pipes and list all the pipe sizes on the drawing

96. Cold water systems session 4
Learning outcome
At the end of this session you should be able to describe the features for CWSC

97. What we will cover Cistern sizes Warning pipe Inlet/outlet positions
Position of float valves
Cistern vent
Open vent pipe
Close fitting lid
Service valves
Cistern base support

98. Cold Water Storage 98

99. Cisterns in lofts 99

100. Pipes and Cisterns in lofts
100

101. C.W.S.C
101

103. F/E and C.W.S.C
103

104. Preventing stagnation

105. Linked Cistern
105

106. Warning Pipe Warning/Overflow
A warning pipe will be required for cisterns up to 1000 litres it consists of 1 single pipe that removes water from the cistern and will alert the customer to an overflow situation via a clearly visible location
106

107. Warning Pipe Warning/Overflow
Overflow Pipe
A warning and overflow pipe are required for cisterns between 1000 and 5000 litres the additional overflow pipe will take the bulk of the excess water away to a suitable drain and the warning pipe will alert the customer
107