In light of the boil water alert that was issued on the 5 November 2019 for Lauderdale, Roches Beach, Acton Park and Seven Mile Beach, property owners on tank water who have received water from a water carrier since the 29 October 2019 please note the following advice and instructions below regarding disinfecting your water tank.
The specific instruction for manually chlorinating your tank should be applied if this applies to you.
We are aware that TasWater will be following up with properties who have received loads of water since the 29 October 2019 and providing further advice.
Looking after your water tank
Water quality safety
Rainwater is generally safe to drink providing it is clear and has little taste or smell. The risk of harmful organisms being present in your rainwater tank is low if the system is well maintained. You should not collect rainwater for human consumption (drinking and food preparation) in areas affected by heavy traffic, industry, incinerators or smelters.
The very young, very old or immunocompromised (e.g. a cancer patient, diabetic, those who have had organ transplants, or are HIV positive) should consider disinfecting the water (details of disinfecting are listed over the page).
Fluoride: Unlike reticulated water supplies, rainwater does not contain fluoride. If rainwater is your major source of water for drinking and food preparation, you should seek advice from your local dentist, school or community dental service or from the Australian Dental Association about alternative sources of fluoride.
Protecting water quality
Making sure water quality is satisfactory depends on correct design and installation, followed by simple, routine maintenance of your rainwater tank and catchment area. Collecting rainwater involves “low” maintenance, not “no” maintenance!
The Tank: Tanks are available in a range of materials (galvanised steel, concrete, fibreglass and plastic), all of which are suitable, providing the tank has been made specifically for collecting rainwater. You may have to wash or flush some types of new tanks before use. The manufacturer should be able to tell you if this is necessary.
When installed, your tank and every access point, (including the inlet and overflow), should be sealed or covered. The inlet should incorporate a mesh cover and a strainer to keep out foreign matter and to stop mosquitoes and other insects, lizards, possums and other animals getting into the tank. The overflow should be covered with an insect-proof screen.
Plumbing permits are required before installing tanks in areas where there is a reticulated water supply. This tank water can be used for the washing machine cold water connection, toilet flushing, outdoor use, pool/pond/spa top up and garden irrigation. There are also building conditions on the size of tanks and the height of tank stands allowed. Please contact Councils plumbing section on 6217 9590 for more information.
Size of Tanks: The size of tank you need to provide the total supply of household water will depend on a number of factors, including:
- Number of residents;
- Amount and pattern of rainfall;
- Roof area and water usage; and
- For some properties, requirements to have an adequate water supply for fire fighting purposes, including providing access for fire fighting vehicles;
The Catchment: House and shed roofs are usually used as catchment areas. Rainwater can be collected from most types of roofs, providing they are not constructed of the following:
- Lead-based paint or coated with bitumen-based material;
- Pesticide-treated timbers; and
- Lead flashing in roof catchments.
Overflows or discharge pipes from roof-mounted evaporative air conditioners or hot water systems should not be allowed to discharge onto the roof catchment area. Some types of new tiles and freshly applied acrylic paints may effect the colour or taste of rainwater so you may need to discard the first few run-offs. Also, if possible, do not collect rainwater from parts of roofs incorporating flues from wood burners.
First Flush Devices: First flush devices are recommended for use, and they stop the first portion of roof run-off being collected and will reduce the amount of dust, bird droppings and leaves that are washed into tanks. Alternatively, you can disconnect the tank inlet, ensuring the first run-off of rain after a dry spell is not collected.
Maintenance
Roof Catchments: Should be kept clean and clear of leaves and debris. Clean out gutters regularly, as rotting leaves in gutters cause corrosion which may taint the water and will eventually cause rust. Consider using gutter guards and remove overhanging branches.
Screens: Insect-proof screens should be cleaned regularly. Do not allow tanks and gutters to become breeding sites for mosquitoes. If you detect mosquitoes in a tank, locate and close the entry point. As a last resort, for most types of tanks, you can add a teaspoon of medicinal paraffin to stop mosquitoes breeding.
Sludge: Check tanks for sludge accumulation at least every 2-3 years. There are risks involved in removing the sludge, so it is recommended that you use a professional tank cleaning contractor to undertake this task. They are listed in the yellow pages of the telephone directory.
Disinfection
Regular disinfection should not be necessary. If you are immunocompromised (see above), are experiencing gastric upsets, or if you suspect the water in the tank is contaminated by bacteria, you can disinfect it by either:
- Boiling the water before drinking or cooking with it. Heat the water and hold at a rolling boil for about three minutes. It can then be cooled and stored in a clean container until required. To improve the taste of boiled water, pour it back and forth from one clean container to another, or let it stand for a few hours, to increase the dissolved oxygen concentration; or
- Chlorinating the rainwater in the tank by adding 40 ml of liquid sodium hypochlorite or 7g of granular calcium hypochlorite per 1000L of water (approx 5mg/L chlorine). The amount of water in your tank can be calculated by the following formula:
3.14 x radius2 x height of water in the tank x 1000
(The radius is half of the width of the tank)
Water carriers in Clarence
Clarence City Council recommends the purchase of water only from licensed water carriers.
For more information about your tank, please contact council’s environmental health services on 03 6217 9570.