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

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

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

Rainwater cycle

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

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

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

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

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.

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 (http://www.weatheronline.co.uk/reports/wxfacts/Precipitation-Map.htm, 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.

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. (http://www.walesdirectory.co.uk/tourist-attractions/Lakes_and_Reservoirs.htm)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Water Treatment

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

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

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

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.

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.

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.

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

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

Then a container 5 metres high would exert 5 times the amount of pressure. 5 x 9.81 = 49.05 kn/m2

? 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. ?

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 45.87 metres in a vertical pipe.

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.

Typical water distribution to buildings

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

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

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

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

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

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

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

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

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

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

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

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

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

Completed connection

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

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

Modern external stop tap and water meter chamber

Meter types Internal External

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

Water meter box Groundbreaker

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

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

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

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

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

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

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

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

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

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

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

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

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)

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

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

Direct system

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

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

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

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

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

Indirect system

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

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

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

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

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

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

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 www.ukcopperboard.co.uk Pipe sizing for hot and cold water part one – basic principles

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

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

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

Cold Water Storage 98

Cisterns in lofts 99

Pipes and Cisterns in lofts 100

C.W.S.C 101

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

Preventing stagnation

Linked Cistern 105

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

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