TYPES OF PLUMBING JOBS
Plumbing covers more than just pipes for home water supply. It also includes pipe networks for provision of gas supply, sprinkler systems, roof plumbing, garden irrigation, grey water systems and waste and drainage systems. The focus of this lesson is mainly on water supply but we’ll touch on some of those other areas first.
Roof Plumbing and Guttering Gutter and drainage systems on buildings do degrade and in significant old building renovations may often need replacing. Roof plumbing includes spouting, guttering, downpipes, roof valley irons and also flashings which we’ve previously covered.
Old guttering systems involved using brackets attached to the timber fascia’s beneath the eaves, which then held a metal gutter. Newer systems often involve metal gutters attached to a metal fascia. Plastic guttering is typically held by snap brackets which lock around the gutter once in place. There are also precast concrete, zinc, aluminium and copper guttering systems.
Guttering is attached to downpipes which in turn feed into the drains. Gutters often collect leaves and other debris which can block the gutters and/or downpipes which take water from the gutters. If a gutter becomes blocked, water may overflow to the back of the gutter and make its way into the walls causing dampness and damage. Alternatively, it can prolong dampness in the metal gutter hence increasing any corrosion.
Downpipes, like gutters can be made from a variety of materials with cast iron being used mostly in the past and plastics and lightweight metals being more common today. Galvanised steel wire balloons are used between gutters and downpipes to prevent blockages.
Drainage Plumbing Plumbing work also involves installing drains to remove waste and storm water from around a building; including roofs, sub floor drainage, sewerage etc. Wastewater or sewage refers to all the liquid wastes of a community although some rural properties may have their own effluent treatment plants. These wastes consist of all the discharges from a variety of plumbing fittings including
dishwashers, sinks and toilets, which are disposed of through sewers. Storm water may also enter the sewers, but in newer houses there are usually separate pipes for its removal.
The construction of sewage and drainage systems form houses must comply with relevant codes of practice and standards. All systems have to be able to transport wastes efficiently without risk of blockages and leakages into the ground. Commonly pipe work must be left exposed after installation then inspected and approved before being hidden (e.g. before filling in trenches). However, it underground pipe work has to remain reasonably accessible for inspection and repair. Inspection chambers or manholes are required to permit plumbing rods to be inserted to release blockages, particularly where here is a change in direction or gradient. Beneath houses drainage pipe have flexible joints and arches or lintels over them to provide relief from excessive loads from walls.
Drainage systems can be combined where the waste from all appliances and gutters ends up in one drain, or separate where the household wastes end up in one drain and surface waste ends up in another. Pipe sizes and gradients vary according to how many properties they serve.
Grey Water Plumbing Grey water is the waste water from baths, showers, basins, sinks, and household appliances which are plumbed in. Grey water can be recycled to cut down on water wastage. It does not include black water which is the wastewater from the toilet. Black water can only be recycled using highly specialised systems which are too complicated for the average home garden. Even then, many authorities do not permit its usage for above ground watering. Black water from houses is taken to treatment plants where impurities are removed before it is discharged, usually into the sea. Untreated black water is very harmful for human and environmental health.
The simplest system for recycling grey water is to divert grey water for irrigation. Grey water from the bath, basin, shower and so forth are redirected into a surge tank rather than straight into the sewage pipes. The usual route into the sewage pipes is stopped off with a ball or gate valve which can be opened to allow grey water back into the sewage system in case of emergency. A valve on the pipe leading to the tank is also required to prevent backflow of grey water into the household supply.
When the basin or bath is emptied, or someone has a shower, surges of water pass into the tank. A pipe from the tank is connected to an underground watering system which distributes water to established trees and plants. The outflow pipe from the tank also needs a gate valve so the irrigation can be shut off. It is wise to have another connection to the main sewer here too. This system is good for intermittent watering. Other more sophisticated methods include filtering grey water or purifying grey water before use.
WATER SUPPLY
In most cases water is supplied to buildings by a water authority. They provide a water main and a connection pipe to each property. At the boundary of each site is typically a stopcock, often below ground but not always, housed in a protective unit. For example, on many city streets it is located outside the house boundary on the pavement and beneath a hinged metal cover. A supply pipe goes from the stopcock into the building and the depth of these pipes is dictated by the country’s code. For example, in the UK it is a minimum of 750mm because of the risk of frost damage. Where the water supply enters the building a second stopcock is located, and usually a draincock which allows the water to be drained from the property’s cold water system.
In modern houses, and older houses which have been re-plumbed, water is usually supplied to cold and hot taps under mains water pressure. Mains water is safe to drink and can be used for brushing teeth and food preparation. In some older houses there may be a cistern or cold water storage tank, typically located inside the roof space. If the tank is in good condition and properly sealed the water should be safe. Older tanks were made of galvanised steel which eventually corrode and should be replaced with plastic ones. The tanks must also be tightly sealed to exclude dust and debris as well as light, have an overflow and vents which are covered with screening to keep out insects. If you do have a water storage tank indoors and it needs replacing it must be done by a qualified plumber using appropriate fittings.
Water Tanks Although most houses have water supplied by the local water authority, many people also choose to catch and use their own water. Given that droughts are not uncommon and most people accept that climate change is real it is possible that in the future water storage might be a requirement for property owners. Capturing your own rainwater relieves the burden on storm water drainage systems in towns, and limits the need for constructing new dams which may impact on the natural environment.
The type and quality of water collected can vary from house to house depending upon where you live, the way it is collected, and how it is stored. For instance, water collected from a rusting iron roof is likely to contain too many impurities to drink. An unsealed tank may become home to mosquito larvae or the final resting place of birds and small rodents.
If you want to collect water which is good enough to bathe in, or even to drink, then you need to give careful consideration to all the materials the water comes into contact with and how it is stored. In most cases it is preferable to use mains water for drinking and use tank water for all other purposes. If you wish to drink your water but are unsure if it is safe, then it is recommended that you have it analysed.
Most stored water is collected from a building’s roof. The amount of water which can be collected will depend upon the average rainfall for your area. You can check your typical rainfall by looking at the weather data on your local government’s website or by consulting the national bureau of meteorology’s statistics.
The amount that can be collected is also dependent upon the area of the roof. For an average household with 100m2 of roof surface space and which is home to 4 adults, one 5,000 litre tank may supply around half their annual water needs(depending upon annual rainfall in the locality). Assuming the tank is filled on average around 12 times per year this represents 60,000 litres of water. If you want enough water to meet all of your household needs then a similar sized household may need one 10,000 litre tank or two 5,000 litre tanks.
Options for materials for water storage tanks include polyethylene (plastic), concrete, ferro-cement (concrete, steel reinforcement bars and wire mesh), galvanised steel (zinc coated), fibreglass, and wood (plastic lined).
Underground Tanks Water from roofs can also be harnessed in underground tanks. These can be constructed on site by digging out a pit and then lining it with concrete. Alternatively, pre-formed tanks can be used. The tank is sealed so that groundwater will not enter. Underground tanks are ideal where outdoor space is at a premium such as in city courtyard homes. They also have the benefit of keeping water cool in summer and unfrozen in winter. However, they can be difficult to inspect and repair should anything go wrong and are more expensive to install initially.
Other Water Sources Besides roofs, water may also be collected directly into reservoirs within the grounds of a property, although without any cleaning system water runoff collected in this way would not be suitable for drinking or washing with. In drought-prone areas it may be worth considering collecting water from the ground using underground drainage systems to relocate it to a reservoir or underground storage tank. This can be an expensive solution but may be worthwhile in the long run when water is scarce.
Another option is to pump water from underground bores or wells. This is done by digging or boring down to underground sources known as aquifers. Water accessed from wells often has higher levels of minerals and may be quite hard. It is also prone to contamination from other aquifers which interconnect with the one being sourced. On many rural properties water may be pumped from a watercourse, such as a dam, for use around the home. For sanitary reasons this water is typically only used for flushing toilets inside the home and for outside purposes such as watering plants and lawns. Again it needs to be pumped to where it is needed.
