Rainwater Harvesting in Oatley Jim Vickery Oatley Flora and Fauna Society Monday 27 th October 2014

Introduction

Rainwater harvesting questions: How much water will I need each day? Where can the rainwater tank be installed to maximise the area of the roof used to collect rainwater? How much rain is going to fall onto the roof? Will the rain come in showers or storms? Best size for the rainwater storage tank?

Typical domestic water usage: L/day No. of people246 Economical toilet Economical toilet & economical clothes washing machine PLUS – water for the garden

Oatley NSW rainfall characteristics: Drier than many Sydney suburbs Misses out on the coastal rainfall that only comes as far as King Georges Rd. Rain from the west tends to go to the north and to the south!

Tank storage perform- ance

A reliable supply

Quarter Average (1993 to 2013) Q1280 mm Q2265 mm Q3184 mm Q4200 mm Annual929 mm Estimate of the reliable draw based on: 1996 – an average year for rainfall 2004 – a very dry winter

Quarter Average (1993 to 2013) Q1280 mm Q2265 mm Q3184 mm Q4200 mm Annual929 mm Estimate of the reliable draw based on: 1996 – an average year for rainfall 2004 – a very dry winter

Usage: L/day100 Roof area: sq m100 Storage: L Minimum water stored during the quarter 1996 Average summer 1996 Average winter 2004 Dry winter Days pa without water

Usage: L/day100 Roof area: sq m100 Storage: L Minimum water stored during the quarter 1996 Average summer 5%52%68%75% 1996 Average winter 0%20%47%60% 2004 Dry winter 0% 9% Days pa without water

Collection equipment

Best value StyleMaterial Indicative cost - $/kL (2,000 to 5,000L) 1RoundPoly$220 2RoundSteel$320 3SlimlinePoly$400 4UnderdeckPoly$550 5SlimlineSteel$600 6UndergroundPoly$700 plus excavation Rainwater tank types and costs

OVERFLOW FIRST FLUSH FINE SCREEN

20 mm dia 40 mm dia 50 mm dia FLAP

External self priming pump with controller mounted above the motor. Submersible pump with external controller – changeover unit

Surface water

Banksia Robur

Conclusion

Rainwater tank installation guidelines: 1.Determine your daily need for rainwater. 2.Determine the size of your available roof catchment area. 3.A 2000 L tank will provide 50 to 100 L/day from a 100 sq m or larger roof. 4.A 6000 L tank or larger is necessary for supplying a washing machine or something similar. If the roof catchment area is greater than 200 sq m then the tank is less likely to empty out during dry periods.

Oatley Flora and Fauna Society 27 th October 2014 Rainwater Harvesting in Oatley Jim Vickery