Rainwater (roof water) harvesting for swimming pools

The use of filtered clean rainwater collected from the roof (not general stormwater runoff) to fill spa pools and swimming pools is supported provided controls are in place to protect public health. Rainwater collected in tanks can be safely used for pools provided it is introduced into the pool through either the balance tank or into the pool at night to allow sufficient time for treatment before bathers enter the pool.

Last updated: 01 June 2010

Overview

Safe rainwater use for swimming pools is achievable in most situations, unless rainwater is collected from roofs either constructed of hazardous materials (such as lead or preservative-treated timber) or located in heavily polluted areas where particulate pollution from vehicles, aircraft and industrial activities may contaminate rainwater.

Research indicates that first flush systems effectively minimise particulate and microbial pollution. First flush systems reduce contamination because the first few litres of rainwater, which contain the highest concentration of pollutants, are discarded to stormwater. Microbial contamination of rainwater can also be easily controlled by chlorination in the collection tank. The area of the roof needs to be considered when determining the quantity of first flush water to discard. The rainwater tank must be maintained and checked periodically for sludge accumulation.

Rainwater can have the added benefits of a low Total Dissolved Solids and is therefore soft water being low in carbonates. In heavily polluted areas, the cost of pre-treatment to maintain safe water may outweigh any benefits, especially where a reliable water source exists. Further information is contained in Rainwater Tanks (2) and Guidance on use of rainwater tanks.(3)

The use of filtered clean rainwater to top-up swimming pools is supported provided controls are in place to protect public health. A suggested risk assessment and management framework is outlined below.

Components to consider in water harvesting for use in swimming pools

(Developed for use with Australian Guidelines for Water Recycling: Managing Health and Environmental Risk (Phase 1), 2006(1)

Framework element	Activity
Element 1: Commitment to responsible use and management of rainwater to top-up swimming pools Components: Rainwater use policy Regulatory and formal requirements Engaging stakeholders	Regulatory framework - compliance Water Quality Guidelines: • NSW Health. Public Swimming Pool and Spa Pool Guidelines(4) Heath risk assessment guidelines: • Australian Guidelines for Water Recycling: Managing Health and Environmental Risk (Phase 1), 2006(1) • EnHealth. Guidance on use of rainwater tanks. May 2004(3) Develop a rainwater use policy
Element 2: Assessment of the water system Components: Identify intended uses Component: Hazard identification and risk assessment	Source of water • Rainwater tank Treatment • First flush system • UFF filtration or other pre-treatment • Disinfection: ultraviolet (UV) • Introduced into the pool plant and not directly into the pool Intended uses • Recreational swimming Exposure routes • Ingestion (100 mL) - more for infants • Dermal: disinfection by-product (DBP) - trihalomethanes (THM) • Inhalation: DBP - THM Assessment of water quality data • Microbial quality • Chemical quality (heavy metals), pH, total dissolved solids (TDS), turbidity Water Quality Indicators • Turbidity (NTU), TDS • Oils and grease • Salts (coastal locations) • Heavy metals (lead, copper) • Microbiological indicators Rainwater to be validated prior to use • Microbial hazards • Chemical hazards • Hazards from failures
Element 3: Preventive measures for recycled water management Components: Preventive measures and multiple barriers Critical control points	Preventative Measures • Prevention - roofing materials, flashing (not lead) • Treatment -best available technology (first flush system) • Validation of treatment system • Documentation of responsibilities, operational procedures • Controls - monitoring, shutdown Multiple barriers/prevention/communication • Rainwater water should be tested prior to use. • Failures should be communicated and reported to the Public Health Unit (PHU) • A contingency plan should be developed to effectively deal with rainwater contamination events. • Education program for operational staff • Validation prior to commissioning to ensure that rainwater complies with the Australian Drinking Water Guidelines in relation to e.g. turbidity, TDS, oils and grease, heavy metals, and microbial indicators. • On-line monitoring of pool water for TDS, turbidity, free chlorine and oxidation-reduction potential (ORP) (may be required) • Determine critical control points
Element 4: Operational procedures and process control	Documented procedures • Operational monitoring • Develop a contingency plan for contamination events • Corrective advice
Element 5: Verification of rainwater quality	• Water quality monitoring • Receiving water monitoring • Documentation and reliability • User satisfaction • Short-term evaluation of results • Corrective action
Element 6: Management of incidents and emergencies	• Communication • Incident and emergency response protocol
Element 7: Equipment capability and maintenance	• Operator, contractor and end user awareness and training
Element 7: Equipment capability and maintenance	• Operator, contractor and end user awareness and training
Element 8: Community involvement and awareness	• Community consultation and education
Element 9: Validation, research and development	• Validation of processes • Design of equipment • Investigative studies and research monitoring
Element 10: Documentation and reporting	• Management of documentation and records • Reporting
Element 12: Review and continual improvement	• Review by senior management • Continual improvement

Reference

1. National Resource Management Ministerial Council; Environment Protection and Heritage Council; Australian Health Ministers Conference. National Water Quality Management Strategy. Australian Guidelines for Water Recycling: Managing Health and Environmental Risks (Phase 1). 2006. Available at: http://www.environment.gov.au/water/quality/nwqms/index.html (Cited 28 April 2009)

2. NSW Department of Health. Rainwater tanks. Sydney: NSW Health, 2007. Available at: http://enhealth.nphp.gov.au/council/pubs/pdf/rainwater_tanks.pdf (Cited 28 April 2009).

3. Australian Government Department of Health and Ageing, enHealth Council. Guidance on use of rainwater tanks. 2nd edition. Canberra, 2004. Available at: http://enhealth.nphp.gov.au/council/pubs/pdf/rainwater_tanks.pdf (Cited 28 April 2009)

4.NSW Department of Health. Public Swimming Pool and Spa Pool Guidelines. Sydney: NSW Health, June 1996.:the NSW Health swimming pool website

Further information - Public Health Units in NSW
For more information please contact your doctor, local public health unit or community health centre - look under NSW Government at the front of the White Pages
Metropolitan Areas	Location	Number	Rural Areas	Location	Number
Northern Sydney	Hornsby	02 9477 9400	Greater Southern	Goulburn	02 4824 1837
Central Coast	Gosford	02 4349 4845		Albury	02 6080 8900
South Eastern Sydney	Randwick	02 9382 8333	Greater Western	Broken Hill	08 8080 1499
Illawarra Shoalhaven	Wollongong	02 4221 6700		Dubbo	02 6841 5569
Sydney South West	Camperdown	02 9515 9420		Bathurst	02 6339 5601
Sydney West	Penrith	02 4734 2022	Hunter/New England	Newcastle	02 4924 6477
	Parramatta	02 9840 3603		Tamworth	02 6764 8000
Justice Health Service	Matraville	02 9311 2707	North Coast	Port Macquarie	02 6588 2750
				Lismore	02 6620 7585

See full Contact details for Public Health Units.