Williams household, Darwin: intake dossier
Release A for the Darwin home: the homeowners' brief, the property as it stands, and what nobody yet knows. Issued in week 1.
Case material. The Williams household and this property are teaching fiction for the Household Resilience Loan Programme case. Dimensions are an internally consistent educational model, not a survey.
Intake note
Kate and Josh Williams run a small business from home and drive south for four weeks every July. They buy water every late dry season and watch their tanks overflow every wet.
They want the wet season carried into the dry, systems that look after themselves while they are away, and the overflow that scours the ground under the house sent somewhere on purpose.
Household: Kate and Josh Williams and their two children, aged 9 and 13. For comparability every case uses the course's demand convention for two adults and two children aged 9 to 13.
- Dwelling
- Elevated steel-frame house (2008) and a steel shed on a 1 ha block
- Tenure
- Owner-occupied freehold, rural-residential zoning.
- Climate
- Bureau of Meteorology station 014015; long-term statistics on the datasets page
In the homeowners' words
- “In the wet the tanks overflow for weeks. In October we buy water. It is absurd.”
- “We are away for four weeks every July and things have to keep running.”
- “The overflow washes out under the house. I want that dealt with.”
- “Anything I cannot service myself in the wet is no use to me.”
Priorities and service targets
The household's priorities, in their order:
- Carry enough of the wet season into the dry to stop buying water.
- Systems that run unattended through a four-week absence in July.
- Overflow sent somewhere deliberate instead of under the house.
- Keep the fruit trees and the main garden producing through the dry.
Agreed at intake as the service targets a proposal must meet. They are checked in an average year; the dry year is where the case for extra spending gets made.
| Target | Service the client needs | Met today? |
|---|---|---|
| T1 | Carted water cut to 20 kL a year or less in the average year | no |
| T2 | Everything runs unattended through a four-week absence in July, with no delivery needed that month | no |
| T3 | Overflow taken to a nominated discharge point away from the piers | no |
| T4 | The main garden (120 m²) at least 60 % watered from on-site water through the dry season, May to October | no |
Attainable, with room to spare. A staff check across the published decision ranges found options meeting all four targets that leave at least $12,500 of the $30,000 allowance and at least 3.5 kWh/day of the energy cap unused. Which option, and whether to spend more than the minimum, is your call to make and defend.
The property
The 1 ha parcel matters mainly for what lies outside the working area. Everything the design touches is inside the 60 × 40 m working area drawn in full below.
Site plan: what covers the ground
| ID | Feature | Area or size |
|---|---|---|
| B1 | Elevated house · Building — on piers; shaded storage slab underneath | 195 m² (roof 248.6 m²) |
| B2 | Shed · Building — steel | 48 m² (roof 56.8 m²) |
| H1 | Gravel drive and turnaround · Hardstand — unsealed | 126 m² |
| H2 | Shed apron · Hardstand — concrete | 36 m² |
| G1 | North garden · Growing zone — productive in the wet, marginal in the dry | 98 m² |
| G2 | Main garden · Growing zone — banana, pawpaw, cassava, sweet potato | 192 m² |
| G3 | West orchard · Growing zone — mango and citrus | 144 m² |
| G4 | Nursery area · Growing zone — shadecloth frame over about 20 m² | 72 m² |
| C1 | Shaded yard · Retained recreation — under the native fig; kept | 90 m² |
| T1 | Existing tank 1 (22.5 kL) · Tank — poly, 2016 | 22.5 kL |
| T2 | Existing tank 2 (22.5 kL) · Tank — poly, 2016 | 22.5 kL |
| E1 | Mango · Tree canopy — large, dense shade | canopy ≈ 7 m |
| E2 | Citrus · Tree canopy | canopy ≈ 5 m |
| E3 | Native fig · Tree canopy — shades the yard | canopy ≈ 8 m |
| X1 | Septic trench exclusion — trench position from the 2008 approval plan; not verifiedestimate | 66 m² |
| P1 | Pressure pump and cartridge filter | |
| P2 | Switchboard and inverter | |
| P3 | Septic tank (approximate)estimate | |
| P4 | Carted-water fill point | |
| O1 | Tank overflow (current) — discharges beside the piers | |
| A1 | Access from the road |
Hatched: growing zone. Dotted: retained recreation. Dashed outline: roof edge or tree canopy. Cross-hatched strip: easement or exclusion zone. Triangles: estimated spot levels. Squares: service points.
Roof and catchment
Roof plan area is footprint plus eaves, plus any roof over hardstand. It is the area that collects rain, and it is not the same number as the footprint or the pitched roof surface. Only the shaded zones drain to storage today.
| ID | Roof zone | Plan area | Downpipes | Now |
|---|---|---|---|---|
| R1 | House, east plane — plumbed to both tanks; carries the 6.6 kW solar array | 124 m² | 2 | to storage |
| R2 | House, west plane — gutter present; downpipes discharge beside the piers | 124 m² | 2 | not connected |
| R3 | Shed, north plane — gutter fitted | 28 m² | 1 | not connected |
| R4 | Shed, south plane — gutter fitted | 28 m² | 1 | not connected |
| T1 | Existing tank 1 (22.5 kL) — poly, 2016 | 22.5 kL | ||
| T2 | Existing tank 2 (22.5 kL) — poly, 2016 | 22.5 kL |
Shaded zones drain to storage now; dashed zones do not. Circles are downpipes. Areas are roof plan area, eaves included.
Floor plan
Enough to locate the wet areas, the fixtures a rainwater or greywater line would reach, and the services. Not a construction drawing.
| ID | Room | Area |
|---|---|---|
| F1 | Kitchenwet area — sink and dishwasher | 22 m² |
| F2 | Laundrywet area — tub and machine; external stair | 15 m² |
| F3 | Bathroomwet area — shower | 8.4 m² |
| F4 | WCwet area | 6.6 m² |
| F5 | Storeservices — solar hot water on the roof | 13 m² |
| F6 | Open living — louvred, cross-ventilated | 38.5 m² |
| F7 | Bedroom 1 and ensuitewet area — second shower | 33 m² |
| F8 | Bedroom 2 | 19.3 m² |
| F9 | Bedroom 3 | 19.3 m² |
| F10 | Verandah room | 19.8 m² |
| Q1 | Laundry stair |
Shaded rooms are wet areas; the darker band is services. Internal walls are indicative.
Areas, and how they reconcile
| Quantity | From the plan | Case parameter | Note |
|---|---|---|---|
| Parcel | 10,000 m² | 10,000 m² | the drawn working area is 2,400 m² |
| Building footprint | 243 m² | ground the buildings cover | |
| Roof plan area | 305.4 m² | 300 m² | within tolerance; 62.4 m² is eaves and roof over hardstand |
| Roof connected to storage now | 124.3 m² | of 305.4 m² that has gutters | |
| Designated growing area | 506 m² | 500 m² | within tolerance |
| Retained recreation outside it | 90 m² | not available to the design | |
| Hardstand | 162 m² | drives, paths, slabs | |
| Other ground | 1,399 m² | the rest of the working area |
Services and ground
Each fact is marked known when it comes from a document or a measurement at intake, estimate when it is someone's estimate, and to be measured when nobody knows yet. Nothing here is surveyed.
- Slope
- The working area falls about 0.8 m to the south-east, where wet-season sheet flow crosses the drive. Estimated from the NT contour layer; not surveyed. estimate
- Water
- No reticulated supply. Tank water, with carted top-ups delivered into the tanks in the late dry season. known
- Sewer
- Not connected. Septic tank and trenches north-east of the house; trench position unverified. estimate
- Power
- Overhead single phase, 80 A, with a 6.6 kW solar array on the east roof plane. known
- Gas
- Bottled LPG. known
- Stormwater
- Sheet flow. Tank overflow currently discharges beside the house piers. known
What is already there
- Two 22.5 kL poly tanks, 45 kL in total (2016), on the house east plane, with a pressure pump and cartridge filter.
- Shadecloth frame over about 20 m² in the nursery area.
- Mango and citrus; banana, pawpaw, cassava and sweet potato in the main garden.
- Two timber compost bays, about 1.5 m³ each.
- Drip and micro-sprays on the main garden, manual valves.
- 6.6 kW solar array on the east roof plane.
Bills the household supplied
Carted water: 6 invoices last year, each for 15 kL at $330 a load. known
Electricity: twelve monthly totals for the whole house; the pumps are not metered separately. known
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 |
Case constraints
- Retained recreation: the 90 m² shaded yard stays.
- Maintenance: up to 4 hours a week when home. Nothing may need attention during the four-week July absence.
- Installation zones: new tanks on the gravel turnaround or the shed apron. Nothing in the septic exclusion zone and nothing under the house.
- Disruption: up to ten working days. The solar array must not be disturbed.
- Permitted uses: all household uses from the tanks, as now, and garden irrigation. Carted water is delivered by a licensed potable-water carrier.
- Overflow must go to a nominated discharge point away from the piers. This is a requirement, not an option.
- Rainwater may serve
- toilet flushing, laundry, showers and basins, kitchen and drinking, other indoor uses, garden irrigation
- It serves today
- toilet flushing, laundry, showers and basins, kitchen and drinking, other indoor uses, garden irrigation
- Care available
- up to 4 hours a week; nothing needed more often than every day; everything survives 28 days unattended
What a design may change
The home is fixed. A design may add storage in the permitted zones (the published steps are 0, 22.5, 45, 67.5, 90, 112.5 kL), connect roof zones R2, R3, R4 that have gutters but no connection, and cultivate up to 386 m² beyond the existing plantings. It may not build roof, buy land, or enlarge anything. The other decision variables are on the method page.
What nobody knows yet
16 facts above come from documents. These do not, and they are the starting point for your measurement programme:
- How far into the dry season the existing 45 kL lasts, month by month.
- How much overflows in the wet, and where it goes.
- Whether the west gutter falls the right way for new downpipes.
- Soil infiltration at a possible overflow discharge point.
- Tank water quality after a wet season of leaf litter.