Notes to accompany 1014 “Water supply”Slides 1-3 A supply of clean water is the fundamental factor in preserving good health, along with an equally effective sewage drainage system. Nothing else is as remotely important. All of our water is ultimately rain, either collected directly, or extracted from rain-fed natural sources. Water comes from surface reservoirs, either natural or manmade, surface rivers or underground aquifers (porous, water bearing geological strata.Slides 4-6 Water is moved from source to user by gravity. Reservoirs are at high level, and pipes run from them down to the end users. Local service reservoirs, holding a few days local supply, will be built on high ground if available. Otherwise they will be built as water towers, next to the community they serve. These towers made need pumps to keep them full. The water will be cleaned and sterilised before entering the service reservoir. Great Britain has one of the oldest water supply pipe networks in the world and it is now well past its functional life. Up to 25% of all water collected is lost through leaks before it reaches the end user. There is a massive process of pipe replacement underway. Old supplies may have lead pipes. These are dangerous and toxic. They must be replaced if discovered on a survey. Modern underground water supplies are always carried in high density blue polythene pipes.Slide 7 Hard water comes from land on soft calcium carbonaceous rocks, such as limestone or chalk. Calcium carbonate dissolves in acid water (rain water is acid due to dissolved CO2). Hard water is perfectly healthy to drink, actually better than soft water. But if heated, calcium carbonate precipitates out as a solid, blocking the pipes. It can be “softened” by replacing calcium with sodium salts in a water softener, but this softened water must not be drunk. It can lead to increased risk of heart attack. Naturally soft water comes from areas of hard rock, such as granite or sandstone. It is safe to drink and will not block pipes. Soft water from granitic rocks may be weakly radioactive.Slides 8-9 Water supply pipework must be underground for protection. The supplying company is responsible for all pipework up to the edge of a private property. There should be an isolation valve at that point. The pipework on the private side of that valve is the responsibility of the building owner. If it develops a leak and is not repaired, the supply company will turn off the supply at their isolation valve, but will not repair the private pipe.
Once inside the building, the pipework rise through the ground floor and its material changes form plastic to copper, which is easier to work with. A supply is taken directly to the kitchen for drinking purposes. The rest rises up to the attic, where it fills a tank. A float valve stops overfilling. An Overflow pipe ensures that if the valve fails, the tank does not overflow. Any water softening must happen after the kitchen drinking supply is taken off, not before.Slides 10-11 Copper pipes are used because they are strong, non-toxic and easy to join and fit taps to. They can either be soldered together, using low temperature blowtorches, or screwed together using nuts and a soft metal ring called an olive. Professional plumbers prefer soldered joints for speed and neatness. Amateurs tend to either use compression fittings, or burn their homes down trying to create soldered joints.Slides 12-13 Cold water is distributed around the house by gravity through pipes connected to the low edge of the cold water tank in the roof. The pipe does not run from the bottom, as there may be a build-up of sediment there. As water runs from a tap, the level drops in the tank, which opens the float valve and fresh water runs up into the tank. If the roof is insulated, the water tank must be kept on the warm side of the insulation, t stop it from freezing. Never run insulation under the tank, always up the sides and over the top. Slides 14-15 Hot water is stored in a copper cylinder, usually at first floor level. It is kept full of water by a cold supply into its lowest point. As hot water is drawn out of the top of the tank, fresh cold water replaces it from the bottom. The hot supply pipe runs up into the roof and hooks over the top of the cold tank. It is open so that any expanding hot water will just drip into the cold tank. If this happens there is a serious fault in the system, probably a failed thermostat on the boiler. Water is heated directly in the hot water cylinder, either by an electric immersion heater, or indirectly by the central heating boiler. This heats water in a closed coil of copper pipe inside the cylinder. This hot pipe heats the water in the tank. This system must be fitted with a safety expansion valve which bursts open if the boiler does not switch off. Otherwise the coil in the tank can explode. The tank must be heavily insulated to save energy. Slide 16-17 Cold water, hot water and central heating systems all form part of an interconnected system of pipes, valves, heaters and water stores. It is essential that a sophisticated electronic control system is used to manage and monitor all parts of the system, both for efficiency and safety
Slide 15 Exploitation is not a bad word. We have to exploit resources to live. The concern is exhaustion of resources, over-exploitation. The whole idea of sustainability is not to stop exploitation of natural resources, but to make them sustainable. To ensure that future generations have equal access to the resources they need as we do. It is not simple to achieve in practice, but we try.Slides 16-21 Much protection for cherished landscapes is managed through government legislation in the form of National Parks, designated Areas of Outstanding Natural Beauty and Sites of Special Scientific Interest (SSSI). There are other designations such as ancient woodlands, which confers some basic protection.Slide 22 The National Trust is a private charity which protects property and land by purchasing ownership and then maintaining in the interests of the nation, as defined by the National Trust. Slides 23-25 English Heritage specifically protects monuments owned by the state. Whilst this primarily concerns buildings, many of those are in fact hugely vital elements of the overall landscape. Slide 26 Read Ian McHarg’s book “Design with Nature” It is a classic and not bettered. From the outset it establishes that we must exploit the landscape, to “reap its bounty”, but we must not destroys it. To achieve that we must first understand it. – McHarg I. 1969 (and 1992) Design with Nature John Wiley – “The world is a glorious bounty. There is more food than can be eaten if we would limit our numbers to those who can be cherished, there are more beautiful girls than can be dreamed of, more children than we can love, more laughter than can be endured, more wisdom than can be absorbed. Canvas and pigment lie in wait, stone, wood and metal are ready for sculpture, random noise is latent for symphonies, sites are gravid for cities, institutions lie in the wings ready to solve our most intractable problems, parables of moving power remain unformulated and yet, the world is finally unknowable. How can we reap this bounty? This book is a modest enquiry into this subject. …” The first paragraphs of Ian McHarg’s classic book “Design with Nature”