Stephanie McDonald debunks some water management myths and talks to manufacturers about why the myths are a thing of the past.
If I design a large roof area, the home owner will be able to collect a lot of rainwater.
Correct, but simple plumbing solutions and gravity flows can usually allow other roof areas, such as a carport, garage or annex roof, to be included within the area from that which rainwater is harvested. The answer is to simply collect rainwater from as large a roof area as possible. Commercial buildings, with their significant roof areas, are another important resource.
- Max Ekins, Davey Water Products
Rainwater tanks are unsightly and interfere with building designs.
Yes, that used to be the case — but not any more. Manufacturers in the rainwater harvesting industry have listened to those concerns and developed products to enable architects and building designers to hide water within the structure of buildings, or alternatively on the exterior of new buildings but in shapes that will not detract from the design. For examples, the latest designs enable rainwater tanks to be clad with whatever materials are being used in the building design.
- Andrew Waudby, Waterplex
Greywater diversion devices are similar to greywater treatment systems.
Diversion devices are relatively inexpensive and provide basic coarse filtration to remove large solid particles. The water can only be used outside in the garden and typically distribute the greywater through sub-surface or sub-soil irrigation lines. The water remains untreated and cannot be retained longer than 24 hours by law, so excess water runs directly to the sewer. Greywater treatment systems (GTS) are more expensive and provide high levels of treatment to ‘clean’ the greywater. Biological GTSs use a process that mimics a natural ecosystem by using micro-organisms to cleanse the water, followed by sand and UV filtration. The water from advanced GTSs is suitable for re-use in toilets, washing machines and in the garden. Recycled greywater can be stored indefinitely.
- Dion Bright, Azuratec
Ribbed, banded or corrugated tanks are stronger than smooth wall tanks.
It has been long thought that tanks with ribbed, banded or corrugated wall profiles are stronger than a standard smooth wall tank. Bands or corrugations can create weak points on the tank in comparison to a smooth tapered wall (where the wall is thicker at the base), which will create a stronger, reinforced tank.
- Jemma Haydon, Action Tanks
I don’t have room to fit in the water storage required by council.
For every 1,000 litres of rainwater storage that needs to be incorporated in a design, 1 cubic metre of space is required. That space must also be capable of withstanding 1,000 kg of weight for every 1,000 litres stored. To optimise storage capacity in a given space, the rainwater storage area must be rectangular or as close as possible to it. But don’t just think of a cube in terms of rainwater storage — think of narrow, tall and long tanks. Think of low, wide and long tanks. Think of tanks in different locations, interconnected but still filling and emptying as a single tank. Think also of different shaped tanks, for example, L-shaped tanks.
- Andrew Waudby, Waterplex
In-slab tanks complicate the slab design or building process.
Most designs are based off displacing foam void formers in waffle slabs, but there can be key differences in relation to the integration of the tank installation into the building process. Construction of a slab often takes place quickly without extensive notice and with very coarse equipment. Early designs of in-slab products required differing excavation heights, changes to the slab reinforcement and engineering analysis. Modern designs fit within existing excavation heights and include standard engineering and reinforcement. This ultimately reduces costs for the builder and simplifies the whole process for all concerned.
- Dion Bright, Azuratec
If I install rainwater storage in a confined space, there will be future issues with removal and replacement because the building may last longer than the rainwater storage.
The introduction of smaller, modular formats for rainwater storage or larger rainwater tanks that can be assembled on-site has relegated this problem to ancient history. These solutions can be installed using manhole or normal door access to get a tank into a limited access space and have it assembled on-site. Just as importantly, if the tank needs to be removed and/or replaced, the process is simply reversed. Typically, these systems will also be able to have parts replaced, so any maintenance or warranty issues do not require the removal of the full system but only the offending components.
- Andrew Waudby, Waterplex
Stormwater retention requires deep excavation and culverts.
In-fill housing typically increases the area of impermeable surfaces on a block of land, which in turn poses a problem for councils with aged or limited stormwater infrastructure. As a result, large rain events increase the likelihood of the drains and streets flooding. Where the council has mandated stormwater retention to mitigate this risk, flat land can then add pump costs as gravity alone cannot be relied on to move the water. Recent innovations in stormwater tanks can avoid the need for deep excavations, concrete culverts and sump pumps by using shallow tanks to exploit the minimal fall available from the home to the barrel drains. Installation of such tanks can be done with a shallow excavation cut below the driveway where the tanks are placed before the driveway is poured.
- Dion Bright, Azuratec
I can only install tanks at the end of the building process, otherwise they will get damaged while building, but at the end of the building process there is limited property access.
That used to be the case — but not any more. The concern faced by builders is that tanks on the outside of a building would be damaged during the building process and the builder would be faced with rectifying the damage or replacing the tank at the end of the building process. Now there are a number of options where tanks can be carried through difficult access areas (even through manholes) and assembled in-situ. That means they can be installed at the end of the building process and the risk of them being damaged is removed.
- Andrew Waudby, Waterplex
