Most of the services for residential buildings are controlled by statuary bodies and work is restricted to licensed tradespersons. Who can do what varies from location to location. For example, all plumbers are licensed to install water. Some need to be specifically licensed to install sewer and storm water drainage. (However not all areas require storm water to be installed by plumbers.) Many plumbers are also licensed gas fitters.
Stormwater
Storm water drainage disposes of roof water, surface water and underground water. Often (but not always) stormwater is deposited into one onsite stormwater drain that then deposits water into the street curb-side gutter or waterway. (Waterway disposal is subject to environmental and local government regulations.)
While some dwellings (mostly in new housing developments) remain never connected to a stormwater system, many local councils now require, (through the BASIX commitment) new homes to have a roof gutter system whose run-off is directed into a rainwater tank. Gutter-less systems can only be used in heavily treed areas that have a well drained sub-soil structure (such as sand) and where there is no BASIX requirement for collection.
Surface run-off can also be collected (if nominated in the BASIX) and directed into a stormwater tank. These tanks come in many forms: sub-floor water bladder storage, above ground concrete tanks, or charged downpipes that store water. All first collection tanks then require a 2nd retention tank for collection of overflow if a downpour occurs.
Storm water may also be directed into an infiltration and sedimentation pit to allow nature seepage into the ground. Absorption disposal systems should be as far downhill as possible from any building. The pit may have an outlet pipe that is connected to council stormwater main. There are also various combinations and alternatives to the stormwater catchments described above.
Stormwater should never drain into sewer system and there are heavy fines for those who flaunt this regulation.
When stormwater pipes are laid it is essential that they are supported on a stable bed, usually sand, and that the fall is 1:50 i.e. 30mm in 1.5m. Other services are usually laid in the same trench for practical reasons. All pipes bend as required at 30 degree angles and have inspection openings at various points.
Sewerage
Sanitary Plumbing
Sanitary plumbing links the house drainage system to sanitary fitments including taps, basins, baths, showers, laundry tubs, sinks and toilets. (Washing machines or dish washing machines are not considered sanitary items, however their waste water must be disposed through the sewerage.)
Regulations vary from place to place as to how much of the installation of these fittings must be done by plumbers and drainers and how much can be done by others (such as DIY owner).
All sanitary plumbing is now PVC pipes and fittings. If these pipes are exposed, installers should ensure there is no unsightly glue visible.
House drainage
The house drainage system connects sanitary pipes to the invert (where onsite sewage pipes meet the authority's main pipe). The threshold where "sanitary plumbing" becomes "house drainage" is usually at, or about floor level. House drainage was once earthen-ware pipes but now plastic is used.
Much of the work in house drainage is the digging of trenches to accommodate the pipe. Falls vary between local authorities but are in the range of 1:20 to 1:60 and piping is only bent to 30 degrees.
Footings should also bear no pressure on pipes. Special pier footings and concrete encasement of pipes maybe required if a building's structure is within the pipes "zone of influence". The zone of influence is calculated using the depth of the pipe location and a 45 degree rise from the outside of the pipe work toward the building.
The house drainage system also requires a vent at the end of the line which now only needs to be 450mm above the roof cladding at that point. Vents should be located away from windows and air conditioners, and preferably out of view.
Main sewer
Waste water is commonly discharged into sewer mains for off-site treatment. If there is no sewer, it is treated on-site through a bio-system which requires a quarterly pump-out. Excess water from this system is distributed over non-consumable areas of the garden.
The house drainage system connects to the local authority's sewer at the invert which could be either on your property or on council land. The sewer diagram (obtainable from your local council) will provide its precise location.
Building over a sewer is possible providing council is aware of your intention and that concrete encasement has been designed by an engineer and certified. Building too close to any kind of council main pushes up the costs of construction and if possible should be avoided.
Grey water usage
With water scarce in many areas of Australia, collecting grey water from washing machines, showers and basins for use on gardens may be a consideration. This decision needs to be made very early in the house design so that the appropriate plumbing can be laid and a dedicated storage tank location can be considered.
Unfortunately some local councils are not that familiar with grey water system so some effort may be required to ascertain which specific reports are required for certification by them. Hopefully this will change with the advent of private certifiers.
Hot Water Systems
The main considerations for an owner about what type of water system to use are:
- The capacity of the system
- How much energy they use. (The water heater is the single biggest contributor to household greenhouse gas emissions).
- The location of the heater/s relative to the outlet. (This determines how much cold water is wasted while the hot water flows to the user. This delay time is much more of a consideration in these days of water scarcity.)
The required capacity of the system, (not relevant for instant systems), depends on the:
- size of the house
- number people in the house
- climate
- lifestyle of the occupants
How big the system should be is both a practical and convenience decision. For a house to never run out of water, a large (and expensive) system may be required. That size system may not be warranted for general usage. For example, a couple in a three bedroom house in a temperate climate may only need a small capacity system, however there will be times when the house may have six people, so consideration should be given to that situation. If that is rare then perhaps a capacity for four people is a good compromise. If the house is in a hot climate then perhaps that could be reduced to a three person system. If it's in a cold climate then a five person system might be a consideration. As a general rule, an off peak storage system have 70 litres per house person, with the washing machine and an extra bathroom counting as additional persons.
Another decision is what type of fuel to use i.e. gas or electricity. That often depends on availability and the competitive tariffs from suppliers in the area.
There are five different types of hot water systems.
Instantaneous
These heat the water when it is being used and provide an endless supply of hot water. Being very small they are a consideration if there is little space. They are quite efficient and have low standby losses because fuel is required only during supply. They are a consideration if the hot water is only used occasionally, or if the house is spread out, or has satellite buildings that require remote hot water (perhaps from additional units). Temperature can be set and varied remotely at the outlet. Flow may be compromised if more than one tap is used at a time from one unit.
Storage
Storage systems hold a practical quantity of water to a set temperature in a large insulated storage container and constantly maintain that temperature for instant hot water. As hot water is used it is replaced by cold water which is then heated to the set temperature. This system is best for houses occupied continuously or for long periods of no usage (when the unit can be switched off.) Mains pressure systems provide multi-tap usage without compromise to flow. (Reduced pressure systems do not.) Once the storage container is depleted, there is a delay of hot water while it is being reheated. Storage systems have higher standby losses than instantaneous systems but special off peak hot water tariffs are available.
Heat Exchanger
Heat exchangers use an insulated container of hot water and a coil of copper tubing through which flows the water to be heated. As water passes through the coil it absorbs the heat from the water in the container which then is reheated to its original temperature. The delay time is similar to a storage system. Heat exchangers require a large storage unit, even bigger than the above dedicated storage systems. They use similar amount of fuel as storage systems and can only supply one tap at a time. They are only suitable for warm climates.
Solar
Solar hot water roof systems work on the principle that hot water (or any liquid) heated by the sun (from flat panels) rises up, to where it can be stored in an insulated roof tank.) They are suitable for warm to hot climates with good (drinking quality) water supply, and can be purchased with a booster for cold months. They supply a similar amount of hot water as a storage system and (depending upon how the booster operates) at a similar temperature. Standby losses are less than storage. They are eligible for government rebates.
Heat pumps
Heat pumps work on a similar principle to solar but the water is heated by the air not the sun. They have no collector panels bur operate like a refrigerator in reverse, transferring heat from the surrounding air into stored water. Heat pumps are highly efficient and use about one third the energy of a conventional electric water heater. Like solar systems, they are more efficient in hot climates, come with an electric booster and are eligible for government rebates.
The Dept of Environment and Climate Change has an informative web site on Hot Water Systems.
Guttering
There are two types of gutters:
- Concealed: usually called a box gutter.
- Exposed: These gutters are available in many profiles and most are available in aluminium or plastic. Many are seamless.
Colorbond gutters allow the gutter colour to be matched to the roof.
Guttering can be installed by anyone. A licensed plumber may well be the best person for this job but he or she will undoubtedly be the most expensive, so a dedicated guttering installer is usually the person for this job.
Leaf guard gutters
Leaf guards are essential for all gutters in bush fire prone areas, and if water collected in rain water tanks is used for drinking. (Leaves can discolour water and make it more acidic.)
One type of leaf guard is fireproof aluminium mesh. One side of the leaf guard mesh is attached by screws to front edge of cutter, and the other is fixed between first and second row of tiles (or screwed down if the roof is metal.)
Gas
Before considering appliances one should ascertain what type of gas is available. There are 5 types of gas the most common being town gas (mains delivered) and LPG (bottled gas). All gas installations must be fitted by a qualified gas fitter. (Most , plumbers usually have this qualification.)
All gas appliances must meet AGA standards, require adequate ventilation (via natural air flow from a window for small appliances), or ducting (for a large appliance) including all heaters. Town gas appliances need to be fitted with a gas governor (to stop excess pressure building up). LPG appliances need a shutoff safety valve to stop gas flow if the pilot light is extinguished. Town gas appliances will not operate on LPG without modification to the jets.
Consumers can now find the best deal for gas suppliers through price comparison websites.