There are two controls to any plan of Legionella prevention hot water storage Australia: one is to have the stored water hot enough to put a lid on Legionella bacteria, the other is to see it out of the household taps at a temperature that will not scald. With most hot-water systems this entails holding the storage at 60°C or thereabouts and then, by means of a tempering valve or similar, controlling the temperature before it gets to the bath or shower.
I am Thomas Ashbury and in my writing I put a focus on the finer points of making life in Australia easier and safer. This guide is about striking a sensible balance when it comes to hygiene and scald prevention. Hot water does not have much glamour but an error in your settings can be as much of a health hazard as a burn. Fortunately a little regular maintenance of the plumbing and some common sense with the controls will see most households mitigate those risks.
Legionella And The Hot Water You Store
In natural or man-made water systems you will find Legionella, a type of bacteria. Inhaling fine aerosols or droplets from a contaminated source can lead to Legionnaires’ disease, a severe pneumonia; the culprit is usually the species Legionella pneumophila.
Drinking the water is not how one becomes infected. It is more of a worry to be breathing in the mist of a spa or spray tap. That is why what is in the hot water tank is of interest; if there is poor water movement or control of temperature the pipework and outlets become a place for the bacteria to make themselves at home. Good household hot tap safety practices are also important.
Not every home presents the same risk. An old system with a thermostat in need of adjustment, sediment in the pipes and branches that have not been used in a while are not to be compared with a well-kept system. When you let the plumbing slide it is a stubborn beast.
Why Growth Can Be Encouraged By Tanks
If water is allowed to sit in a pipe or tank for long periods and is merely warm instead of properly hot, the risk of Legionella in the household system goes up. What is a pleasant warmth for a person is an ideal environment for the bacteria to thrive.
Then there are dead legs, sections of pipe off the main system like an outdoor sink or where an appliance was once connected that are seldom put to use. The stagnant water there will not get the heat or fresh flow of the rest of the system.
Some Things Homeowners Overlook
You will find homeowners who think they can turn the thermostat down for the sake of the bill and no harm will come of it, or that a tap running hot for a moment is proof of a sound system. Do not rely on such assumptions. There may be cooler than intended pockets in the tank or pipework even if the outlet is hot.
It is also easy to conflate the temperature at the tap with that of the storage. They are not one and the same. While the tank has to be hot for the purposes of Legionella control, the water coming to the shower should be restricted to avoid burns.
Temperatures For Storage And Delivery
The norm in Australian plumbing for a stored hot-water system is to have it at 60°C or above to deal with Legionella. What is put through to the sanitary fixtures in a residence is typically capped at 50°C with an appropriate device, though state and territory rules can vary for certain premises. Maintaining temperatures above 60°C is essential to effectively control Legionella growth in stored hot water systems.
Leave the tempering valve and thermostat alone and do not make adjustments on a hunch. A qualified plumber with the proper qualifications will look at the layout of the pipes, the valves and the tank and outlet temperatures. One would want this done after a hot-water replacement or renovation, or if the water is either never hot enough or dangerously so.
| Part Of The System | Practical Control | Why It Matters |
|---|---|---|
| Storage tank | Maintain at 60°C plus as the system and an expert would have it | To deny Legionella bacteria the conditions to multiply |
| Hot-water pipework | Short runs and no unused branches | Fewer cooler pockets and less stagnation |
| Shower and tap | Control the delivery temperature | Scald prevention and safety as per Australian practice |
| Tempering valve | Get it looked at if the temperature is not consistent | A way to have hygiene in storage and safety at the point of use |
Take these as a practical guide but not as licence to disregard what the manufacturer says or local requirements. For a proper reading of the Australian Standards and the plumbing that pertains to hot-water services, a licensed professional is the one to ask. Depending on whether the home is fitted with a gas, electric, solar or heat-pump system, the protocol for inspection will vary.
Practical Prevention For Homes
The way to prevent Legionella in a hot water tank is to have a system that is well maintained and active and hot enough. The most effective method is to pair proper temperature control with a sensible approach to using each outlet.
- Adhere to the storage setting put forward by the manufacturer of the system and your plumber for Legionella control.
- Where the situation calls for it, employ an approved means of controlling the temperature such as a tempering valve that is in compliance.
- Make a habit of running showers and hot taps you do not often use, but do so without any undue exposure to scalding water.
- Any dead legs should be looked into and superfluous pipe branches capped off or taken out.
- As per the manufacturer, clean the tap outlets and showerheads.
- Should the water develop an odd smell, the system prove noisy or there are temperature irregularities, put in for some plumbing maintenance.
- And when it comes to servicing the components of a solar or heat-pump, the valves, filters and tanks, the manufacturer’s instructions are to be followed.
A good practice is to give the outdoor fixtures, laundries and guest bathrooms a once over instead of concentrating on the main shower alone; an ensuite that sees little use can all too easily be the part of the system one forgets. A tap left for weeks should be flushed with care, the outlet pointed away from the face to keep from making a spray of it.
If You Have One Day
For a quick review of the household, make a start at the hot-water unit and then look at the outlets in regular use, both the hottest and the coolest. Take note of the age of the system, any leaks in plain sight, protracted times for the water to run hot and what type of system it is. Put down the model number on camera from the data plate before the plumber is called, it spares one the trouble of having to recall and describe it.
There is no point in putting in a new tank right away, professional testing of the temperature is what matters. A service call could turn up a thermostat that has given out, scale, sediment, a section of pipe with no insulation or a valve out of adjustment. Since costs will differ by system and where one is in Australia, get a written estimate from the plumber for the labour, parts, travel and any compliance work involved.
Scald Prevention And Safe Taps
One has to take into account burn prevention as well as the Australian guidance on hot water temperatures for Legionella. In a matter of seconds water from a storage tank can inflict a bad scald if it is hot enough to deal with bacteria, children and the elderly being especially vulnerable as are those with limited mobility or sensation.
The answer is not to put the whole storage system down, which would only be conducive to bacterial growth. Better to leave the storage at the requisite heat and manage what is delivered via a tempering valve in good order. Do not put it to a child to decide on the temperature; see for yourself with the bath or shower and be mindful of whether an older member of the household could react in time to a tap that runs hot unawares. It is a matter of engineering and common sense.
Cleaning, Flushing And Servicing
You will not find a flushing interval for an Australian hot-water system that is universally applicable. What is required in the way of service is dictated by the design of the tank, how old it is, the quality of the water, the manufacturer and even if the property has been empty for a while.
An inspection by a professional is worthwhile for many systems, especially in a home with hard water or an older tank and long spells of low occupancy. The plumber will know if the sacrificial anode is in need of attention, if the tank should be drained and the valves are doing their job.
Maintenance Warning Signs
Rusty or cloudy water, a lack of pressure, poor flow from the hot side, leaks, a system that will not recover or makes an odd rumble are all cause for an assessment. They may not be evidence of Legionella but they do suggest the system is in want of some attention.
When a property has been vacant, do not think to just put on every tap for a few seconds and be done with it. Flush in a controlled manner and have a licensed plumber opine if something more extensive is in order. Leave the planning of thermal disinfection to the professionals, the very hot water presents a scald risk.
Who Needs Extra Protection?
While illness does not automatically follow for the healthy person exposed to Legionella, there are those at greater risk of a severe case of Legionnaires’ disease: the elderly, smokers, those with chronic lung problems or a compromised immune system.
Those with a serious medical condition would do well to consult their doctor on the individual risk as opposed to taking online advice on temperature. Where a household has someone who is at risk, extra caution is warranted with respect to shower aerosols, maintenance and any respiratory symptoms that are out of the ordinary.
An ordinary home has nothing on the water-management obligations of a large building, commercial lodging, healthcare or residential aged-care premises. The onus is on operators to adhere to Australian Standards and the dictates of public-health and building codes; one should not put stock in household guidance as being a full compliance solution.
Symptoms And Medical Action
A case of Legionnaires’ disease will present with fever, chills, a cough, muscle pain, headache, fatigue, shortness of breath and at times gastrointestinal trouble. But since these are indistinguishable from other respiratory infections, the symptoms by themselves do not tell you the source.
Should there be any chest pain, marked difficulty in breathing, confusion, severe weakness or a respiratory illness that is deteriorating, medical advice is to be had without delay. It is pertinent to let the clinician know of any recent travel or exposure to hot-water aerosols, cooling systems or spas. While NSW Health can be consulted for the public-health facts on Legionnaires’ disease, an urgent matter is for a medical professional or emergency service.
Frequently Asked Questions
What is the right temperature for hot water storage in Australia to keep Legionella at bay?
As a rule of thumb it is 60°C or above, but the system and what is required of it will determine the proper setting. A licensed plumber is the one to put his stamp on it, not the thermostat dial.
Preventing Legionella in a hot water system?
Control the storage temperature, see to it that outlets are cleaned and dead legs removed, run those that are seldom used and have the plumbing serviced. Do not conflate the two: the tank may be running hotter than the water coming out of a shower in safety.
Is there a risk of growth in a domestic hot water tank?
Under the right conditions yes, where water is more warm than hot and left to stagnate or is compromised by biofilm and sediment. That is not to say every tank in a house is contaminated. Risk is mitigated by maintenance and use at the correct temperatures.
How frequently does one flush a hot water system?
It is not something that can be put on a schedule for all homes. Have a qualified plumber look at the condition, design and age of the system and the water quality and heed the manufacturer. One would want to attend to it sooner if the property is unoccupied or there are issues with flow, temperature or sediment.
Who is most vulnerable to a bad case of Legionnaires’?
Those with a weakened immune system, chronic lung problems, the elderly and smokers (past or present) are more prone to it. Any serious respiratory symptom warrants a prompt visit to the doctor.
What safe tap temperature should be expected in an Australian home?
Through a tempering valve or similar, residential sanitary outlets are kept to 50°C or under, though this can differ according to the fixture and property. After any work has been done on the place, have a licensed plumber put the outlet temperature to the test.
Make The System Boringly Reliable
There is no mystery to the prevention of Legionella in stored hot water: maintain the equipment, have no stagnant sections, control what is delivered and make sure the tank is sufficiently hot. Manageable details they are.
I have a simple rule to it. When the system is old or sees little use, do not think a tweak of the thermostat is a panacea; have it inspected. You want a hot-water system that is reliably hot in storage and of a sensible warmth at the tap, so dull in fact you do not give it a thought before your morning coffee.