The recent outbreaks of hot water Legionella in Queensland mainly in hospitals is of concern. These, for the most part, were warm water systems which are not the same as your home hot water storage tank.
With hot or warm water systems there is always some risk but every system checked in recent weeks by Whywait Plumbing has had hot water temperatures that virtually eliminate all risk. However, there is almost no risk of you or your family contracting Legionella bacteria as a result of it breeding in your home hot water system.
Legionella Transmission Via Hot Water
Legionella transmission is airborne via respiratory droplets containing the bacteria. Warm water and domestic hot water systems that are contaminated will generally see the transmission of the bacteria in a shower that has not been used for a period of time.
Hot Water Preventative Measures For Legionella
Hot water systems should be maintained so that water at the point of use at any tap or outlet is 50°C or more after having been turned on for one minute.
Hot water systems should not be used until they have reached 50°C especially if they have been turned on for any period.
Generally, domestic hot water systems should have a temperature of 60°C or higher in water leaving the hot water storage tank.
DO NOT turn down the thermostat on an electric hot water storage tank to below 60C.
Hot Water Temperature For Preventative Of Legionella
Hot water systems should be maintained so that water at the point of use at any tap has a temperature that affects the survival of Legionella as follows:
- Above 70 °C – Legionella dies almost instantly
- At 60 °C – 90% die in 2 minutes
- At 50 °C – 90% die in 80-124 minutes, depending on strain
- 48 to 50 °C – Can survive but do not multiply
- 32 to 42 °C – Ideal growth range
- 25 to 45 °C – Growth range
- Below 20 °C – Can survive but are dormant, even below freezing
What Is Legionella Bacteria or Legionnaires Disease
What it is:
- Caused by the Legionella bacteria, commonly found in creeks, ponds and soil.
- Rare in people under 20 years, with those over 50 years old who smoke or have a weak immune system particularly susceptible.
- Non-specific flu-like symptoms including fever, headache and muscle aches, developing within a week of breathing in the bacteria.
- Usually progresses rapidly with pneumonia symptoms, high fever, shortness of breath and chest pain typical.
- A person with the disease usually needs to be admitted to hospital for antibiotic treatment and care.
- Early diagnosis and antibiotic treatment important, and those treated usually begin to improve with three to five days.
Testing Your Storage Tank
For most homes, there is a very little risk of you having hot water legionella occur in your hot water storage tank unless you do really stupid things such as turn off your heating source.
An easy test of the storage temperature is to get a thermometer and test the temperature of your water from the overflow relief valve drain.
If you have any doubts about the temperature in your storage tank contact Whywait Plumbing to organise a service call to check your hot water system.
Judging by the number of phone calls in the last few days to Whywait Plumbing there is genuine concern amongst our clients over the threats posed to them from Legionella risk in their domestic hot water systems.
We can assure you whilst there is always some Legionella risk, there is almost no risk of you or your family contracting Legionella bacteria as a result of it breeding in your home hot water system.
The outbreak of Legionella bacteria in the hot water system at Wesley Hospital that killed a 60-year-old cancer patient and left a 46-year-old woman seriously ill has minor ramifications to be sure because all hot water systems can pose a risk.
That potential risk is why Whywait Plumbing is constantly advocating appropriate maintenance on your home hot water system to minimise that risk even further.
However, there is a huge difference between your home or domestic hot water system and the warm water recirculating system at Wesley Hospital. The Legionella outbreak in their warm water system has not been as a result of contamination in the hot water storage system or the hot water pipes but appears to be literally at the point of delivery from the shower where the water is cooler.
A warm water system is vastly different to your home hot water system with Wesley’s water temperature set between 42.5°C and 43°C. This is lower than the maximum 45°C legislated in the Plumbing and Drainage Act for hospitals. This low-temperature setting is a result of guidelines from Queensland Health that dictate hot water temperatures in hospitals be reduced to avoid the possibility of serious burns to young children and elderly patients. The downside of this requirement is that the possibility of Legionella bacteria surviving in reticulation pipes is increased. Water temperatures of around 46°C will kill legionella bacteria.
Warm water systems are typically found in care facilities, such as nursing homes, hospitals and child care centres, where water for purposes such as bathing and cleaning is provided at approximately 45°C to prevent scalding.
Your home hot water system if it is a storage tank is heating the hot water to between 60°C and 70°C. If you have a tempering valve or thermostatic mixing valve (TMV) installed then that has been set to deliver hot water at 50°C at each individual tap.
If you have no tempering valve installed, you virtually have eliminated all risk. But you have increased the risk of someone suffering a scalding from hot water. As always it is about managing risk.
However, there is an urban myth prevalent that you can reduce electricity costs by turning the thermostat down on an electric storage unit to 50°C. This is not recommended for many reasons but it will not save you electricity and to physically get a thermostat down that low requires physically breaking the locking mechanism on it that allows the setting to be between 60°C – 70°C. If you want to lower the delivery temperature the only acceptable and compliant method is to install a tempering valve.
In 99.99% of cases, the temperature ranges your hot water system operates in is almost certainly killing any Legionella bacteria. The risk if any, is after the storage tank in the reticulation pipes. By turning your shower on and running the tap with hot water first then cooling down with cold water to your desired shower temperature you are virtually eliminating what risk there is.
What the outbreak at Wesley Hospital has confirmed is that there is a risk from warm water and that maintenance of your hot water systems will manage and eliminate that risk.
What Whywait Plumbing do recommend is that you take advantage of our ongoing reminders and offers to service your tempering valves. This not only ensures that water is being delivered at 50°C but eliminates any possibility of Legionella. It also ensures you are complying with the requirements of most insurance policies in ensuring that routine maintenance is undertaken plus we provide you with a written report and a form 4 compliance certificate that is further evidence of your hot water unit being compliant.
The Easter long weekend is only surpassed by the Christmas and new year period as a time when families travel to be together. It is also the start of the hot water season when clients are reminded of the ever-increasing hot water electricity cost.
For the plumbers at Whywait Plumbing, Easter is a busy period with blocked drains being the most common problem followed by hot water problems.
Unlike Christmas, there is always a spike over Easter in emergency callouts for faulty hot water units. That is because Easter is generally much cooler than Christmas. Around April, we all suddenly realise that cold weather is on the way. Every year we notice the signs with an increase in emergency service callouts with the problem being no hot water. Even in the relatively mild climate of South-East Queensland no-one willingly wants to have a cold shower.
Frequently we cannot help but shake our head’s at all the stress, the waste of time and money these emergency service calls represent to many homeowners. Sadly many of us do not pay too much attention to the myriad of household and mechanical systems that provide so much comfort and convenience in our modern lives. We take for granted our water heaters, toilets, mixer taps, and air conditioners that is until they stop working. Then come the panicked call and a repair job that always ends up costing more than we expect.
Showers are the activity where we use the most hot water. Generally, 40% of the water consumed in the shower is hot water. This is why there is a strong correlation between the length of a shower and the hot water electricity cost.
If your home is like many in South East Queensland you are producing hot water from an electric hot water service connected to tariff 11 with a shower rose you love because you get a deluge of water from it at 23 litres per minute. If your shower is being utilised four times a day for an average of 5 minutes per shower, then those showers are costing you $1125 a year in electricity costs and $107 in water usage costs.
Essentially 1 kilowatt-hour of electricity is used to produce 15 litres of hot water using an electric element hot water service. With electricity prices expected to increase 21% on 1 July and a further 40% over the next three years, there is considerable scope for reducing your hot water electricity cost.
One option is to change your electricity and water guzzling shower rose to a water efficient shower rose using only 9 litres per minute. Based on the standard example above this would immediately reduce your electricity costs to $440 and water cost to $42. If you are able to change your hot water service from tariff 11 to tariff 33, then you will save an additional 40% on electricity costs.
The best option and the one we recommend is the long-term sustainable option utilising heat pump technology. Heat pump technology involves replacing your old fashioned energy-hungry electric hot water service to the highly efficient Sanden “Eco®” Plus Heat Pump hot water system.
Electricity costs have become a political hot potato, with state and federal governments playing the blame game in blaming each other for the doubling of electricity prices in recent years.
Hot water electricity cost is one area you can reduce your electricity costs substantially by being smart about how you heat your hot water and use it. Hot water generated by electric elements is something we always took for granted. That is until surging electricity price increases made us all take another look at our increasingly energy-intensive lifestyles.
Queensland law since 1995 has been that hot water delivered to bathrooms be regulated so that it does not exceed 50°C. The most common method to achieve this is by installing a tempering valve.
At 60°C, a severe burn can happen in 1 second.
At 55°C, a severe burn would take 10 seconds.
At 50°C, a severe burn would happen after 5 minutes.
If your hot water unit has a valve that looks like the one pictured on the right, then you have a tempering valve installed. The most common valve installed has a blue cap, but valves used on gas units frequently have a green cap and those on solar or heat pump units have an orange cap.
It is almost a guarantee that your valve has never been serviced as most homeowners do not realise they even had such a device or that they are required to be tested and certified annually. Very simply a tempering valve blends hot and cold water to deliver hot water at a constant temperature and thus reduces the risk of scalding accidents.
Recent litigation places a deed of care to ensure the safe delivery of hot water in domestic situations. Very simply this means you should be having the tempering valve serviced annually whether you are a homeowner or a property investor or a real estate property manager. To ensure your hot water delivery is safe, you need an annual report signed by a licensed plumber that states:
- the model, manufacturer and identification of the tempering valve installed
- the temperature of the hot water recorded during the test
- details of the test undertaken, details of what maintenance was undertaken and what parts were replaced
- the location of the valve in the property
- a reference to the test method undertaken being compliant with AS 4032.3, Appendix C
Duty of care provisions applies to us all and without an annual test and a written report you leave yourself liable if anyone suffers a burn from your hot water. Most electric hot water units heat water to 70°C, so that has the potential to produce a severe burn in 1 second without a correctly working tempering valve.
Whywait Plumbing is contacting clients to book in compliant testing, maintaining and reporting of your tempering valves but if you have any concerns over the temperature of your hot water, contact us now to schedule your service.