Conserving Hot Water Gives A Better Return Than Any Diverter, Relay, Or Heat Pump Hot Water System

shower of money

In all the excitement that is solar hot water, simple efficiency often gets forgotten.

I’ve been writing a lot about hot water lately and how to use the energy of the sun to get it.  In fact, I’ve been concentrating on it so much I’ve neglected my other duties and gotten into hot water as a result.  Mind you, this may have all been part of my cunning plan, as I do enjoy a hot spa.  And if it is heated by people’s hot tears of rage and frustration over my failure to do as I have promised, well that’s just me being energy efficient.

Because that’s the kind of guy I am — efficient.

This article is all about energy efficiency.  Specifically, hot water conservation.  Before spending $1,000 or more on a solar hot water diverter, a hot water relay, or a heat pump hot water system to reduce the amount of grid electricity or natural gas used for water heating, I think it is worthwhile to see if hot water use can first be cut by taking a few simple steps. This is because simple conservation can provide a far better return on investment than anything else.

I’m afraid I don’t have any brilliant new ideas for cutting hot water use and it’s quite likely you’ve heard all my suggestions before.  So if you already know all you need to about:

  • Water saving shower heads and water saving discs.
  • Using cold water for clothes washing.
  • Insulating pipes, and..
  • Hunting down and destroying hot water leaks.

Then feel free to skip this article.  Go read this 12 year old piece on North Korea that appears to have been written by President Trump1 or something instead.

Water Saving Shower Heads

Water saving shower heads are not a new thing.  They have been around a long time and chances are you have them already.  I was going to look up what exactly what Australia’s building codes require for shower head efficiency, but the site I was using wanted to charge me money to download them and I decided that while ignorance may not be bliss, it is at least affordable.

According to the Australian government an old fashioned, non-water saving, profligate shower head uses 15 to 25 liters of water a minute.  Any shower head you can buy these days normally has a three star rating, which means it will provide approximately 9 liters of water per minute or less.

I went to a local branch of a large hardware chain store to see what they had on offer.  I don’t want to give them free advertising, so I’ll just name them after my favorite anti-social activity and call them Punnings.

The majority of shower heads at Punnings stated on their packaging they would provide 9 liters of water per minute, but the cheapest one available said it would provide 8 liters a minute for the low price of only $15.  Unfortunately there was a huge price jump to the next most efficient shower head, which was 7.5 liters a minute for $89.

Ultra Low Flow Shower Heads

Those who want the smallest amount possible spurted on them in the shower can invest in something along the lines of the Methven Kiri Satinjet Ultra Low Flow shower head:

Ultra Low Flow Shower Head

This flying saucer looking thing is supposed to have a flow rate of only 4.5 liters per minute. Image credit: Pure-Electric / Methven.

Which is the self proclaimed lowest flow shower head available in Australia, providing only 4.5 liters per minute .  The word kiri in its name is Japanese for fog or mist.  It also means “cutting”, as in hara-kiri, but I’m pretty sure that’s not the connotation they were going for.  Otherwise it would be called the Methven Kiri Satanjet Ultra Low Blow.

This type of shower head costs around $150.  Unfortunately, not everyone will be satisfied with only only being sprayed with 4.5 liters a minute.  So before you get one, you may want to first try out the cheap water saving discs I describe further down.  If you find the 6 liters a minute they can provide is fine, then you may be happy with only 4.5 liters.

Personally, I’m happy with only being dribbled on, but that’s just the kind of guy I am — dribble happy.

Savings From Water Saving Shower Heads

If you don’t have water saving shower heads already, they make a lot of sense.  Not only will you save on energy, you’ll also reduce water bills.

My parents pay 17.4 cents a kilowatt-hour to heat water using tariff 31 in Queensland.  If they run their shower for an average of 10 minutes a day at the usual shower temperature of 41 degrees2, then each 1 liter reduction in shower flow per minute will reduce their hot water use by 1,700 liters a year.  This is enough to save them $15.50 a year.  So if their shower head went from 9 liters a minute to 4.5 their annual savings would be $70.

Also, because they pay 0.15 cents a liter for water, changing to an ultra low flow shower head would save them $25 on their water bills for a total annual saving of almost $100.  If they ran their shower for a total of 20 minutes a day, as many larger households do, they would save close to $200 a year.  This is a far better return than any solar hot water diverter, hot water relay, or heat pump hot water system can offer.

In Perth the savings would be even higher for people using standard electric hot water systems, due to the lack of cheaper controlled load tariffs used for heating water.  The savings are likely to be less in the rest of Australia, where controlled load tariffs are generally cheaper than in Queensland.

Water Saving Disks For Showers

Shower heads are rated for a certain number of liters per minute, but it’s only an approximation.  What really determines the flow is the water pressure.  If it’s low then changing to a water saving shower head can reduce a spray to a dribble.  If being dribbled on is not your thing, then getting a low flow shower head may not be for you3.  But provided your water pressure is high enough, you can use a water saving disc to reduce the flow at very low cost without needing to replace your shower head.

Water saving discs look like this:

Water Saving Discs

Water saving discs. Image credit Punnings. I mean Bunnings!

The red ones reduce your flow down to 9 liters a minute and the blue ones 6 — depending on your water pressure.  To install them, remove the shower head and put a disk in the pipe that connects to the shower head.  There is a video here showing how to do it by an organization with a name very similar to Punnings.  (Maybe Punnings should sue.)  There will probably already be a disk in there, so how much of a reduction in water flow results depends on how it compares to its replacement.

Also, if the water flow in your shower is too low for you, the disc that is already there can be removed and either replaced by one with larger holes or not replaced at all.

At $5.84 at Punnings for a packet of four, it is probably the cheapest way to cut your hot water use.  There are other methods for reducing shower water flow, but trying this first makes a lot of sense.

Free Shower Head Swaps For Victorians!

Victorians can trade in their old shower heads for water efficient ones, free of charge.  Personally I’d rather just pick up a new water saving shower head from Punnings, or water saving disks, but that’s just the kind of guy I am — incredibly rich.

Shower Timers

Shower Cutoff Daddy

Shower cutoff timers evolved from Terminators.

If you are a masochist, you can pay hundreds of dollars to have an automatic shower cutoff timer installed that will stop your shower operating after 5 minutes or whatever period of time you program into it.  It will then prevent you from turning the shower back on again.

Personally, I’d rather spend my money on increasing the amount of hot water I have rather than paying money to be punished by a machine for using too much of it, but that’s just the kind of guy I am — not completely stupid.

Fortunately, you can get a water proof timer for your shower that will just beep at you and remind you to get a wriggle on.  Which is only mildly annoying rather than being a mechanical device with a heart of pure evil.

Use Cold Water For Washing Clothes

Modern laundry powders and liquids are amazing.  I don’t even bother using a washing machine anymore.  I just soak my clothes overnight and they are ready to go.

My children are less enthused about the wonders of modern chemistry.  Rather than celebrate our new found freedom from mechanical washing, they describe this behavior as, “Daddy broke the washing machine trying to fix the squeak and he’s too cheap to buy a new one.”

But that’s kids for you.

And that’s just the kind of guy I am — cheap4.

For those of you who are still shackled to conventional notions of clothes washing and insist on using a machine, there is no real need to use hot water.  For most people and most loads of washing cold water will do fine.

I am no expert on clothes washing and if you want to tell me that warm or hot water is better for removing some kinds of stains I’m not going to argue with you.  I’ll just I’ll take your word for it.  But Choice magazine says there is little difference, so if you haven’t tried cold water I’d suggest at least giving it a go.

A front loading washing machine will use around 7 to 10 liters of hot water for a warm wash.  If it averages 8 liters and you do three loads a week, that will come to 1,248 liters of hot water a year.  If you pay 17.4 cents per kilowatt-hour of electricity to heat it, using cold water will save you around $11 a year.  A top loading washing machine is less efficient and so may cost you twice as much.  This means switching to cold water won’t save a large amount of money, but if you can’t notice any difference with your clothes, it’s still worthwhile.

Insulating Pipes

When I went to Punnings I spoke to a man there about insulating hot water pipes.  He didn’t seem to think it was necessary in Australia’s climate.  But for people who want to give it a go, they had plenty of foam rubber insulation tubes, at a few dollars per meter, for different diameters of pipes:

My Punnings advisor was probably correct that pipe insulation won’t make a large difference for most Australian homes.  Unfortunately, I don’t know enough to estimate how cost effective it may be.  The general consensus appears to be that it’s not worth paying someone to do it for you, but if you are happy enough to do it yourself, it may save you a few dollars a year and eventually pay for itself.

It is also possible to get a valvecosy, which is an insulating cover for the valve on your hot water system.  It costs around $20 and will probably take a very long time to pay for itself.  But it does have a drainage channel, which is important, and will probably look a lot better than a valve hood you fashion yourself out of foam rubber5.

If you want far more detail about the effects of pipe insulation than you probably want, you can get it here.

Eliminate Hot Leaks

20,000 Drips Under The Sea

It can, but it probably won’t. And who leaves a tap dripping for a whole year anyway? Image Credit: The Victorian Government.  (Or possibly Skynet depending on just what time this article gets published.)

According to the Victorian Government, a leaking tap can ooze over 20,000 liters a year.  All I can say is, that’s one hell of a leak.  More of a trickle really.  But such hot water leaks can exist and I’m afraid some homes leak hot stuff like a British cabinet during a sex scandal.

If you did have a 20,000 liter a year leak in a hot water tap and you pay 17.4 cents a kilowatt-hour to heat water, which is what is typically paid in Queensland, then it would cost you $180 a year in electricity.  Most tap leaks aren’t going to be nearly that bad, but it is still definitely worthwhile to replace the washer as soon as a drip starts.  If you don’t know how to do that, my brother knows, so get him to do it for you.  (Tell him I sent you.)

But while leaking taps can be bad, a leaking hot water system is potentially much worse.  A friend of mine, a beautiful Scottish lass with flaming red hair on account of how she strongly believes in stereotypes6, had a leaking outdoor hot water system and it ended up costing her hundreds of dollars per quarter before she worked out it was because the hot water system had been leaking all that time.  The reason her electricity bills were so high was definitely not because I had been secretly living in the roof space of her home, as she had long suspected.

Small Steps Can Have A Large Payoff

Reducing water flow from your shower heads or fixing taps as soon as they start dripping doesn’t seem as exciting as installing a hot water diverter or relay or a fancy new heat pump hot water system, but that’s only because it isn’t.  It’s not new, it’s not exciting, and you can’t really boast to your friends about how you’re really conscientious about fixing drips as soon as they start.

Well, I do.  But that’s just the kind of guy I am — a big drip.

But what these changes can do is provide a better return on money invested than any of the above methods. By all means invest in an efficient water heating system, but make sure you invest in hot water efficiency first.  Because simply changing to an ultra low flow shower head can provide a rate of return of over 100% per year and, since it costs nothing at all, washing clothes with cold water can provide infinite return.

While you may fear creating an infinite return will destroy the world’s economy, I say go ahead, do it!  Because that’s just the kind of guy I am — utterly reckless.

Or mildly economically literate.  Either one.

Invest in water hot water efficiency and you’ll soon be able to afford to swim in real water rather than worthless gold.


  1. That is, written by President Trump before he underwent Presidential puberty and blossomed into a full fledged alpha President.
  2. Generally, lower flow shower heads don’t cause people to increase the temperature of the showers they take to make up for the decreased amount of warm water flowing over them.  This is because in cool weather humans normally just shower at around 41 degrees and temperatures much in excess of this are aversive, which is another way of saying it’s too bloody hot.  So while there may be an effect, it’s only likely to be small.
  3. But when I was your age all we had was a dribble, and we were glad to have it!  And after we had been dribbled on, we had to force the dribble back up the spout for the next person to use!
  4. Ladies…
  5. But probably not as nice as one you get your grandmother to knit for you.  Or your grandfather.  Let’s not be sexist here.  Not after I’ve gone through all this effort to be ageist.
  6. No, not Pauline Hanson.
About Ronald Brakels

Joining SolarQuotes in 2015, Ronald has a knack for reading those tediously long documents put out by solar manufacturers and translating their contents into something consumers might find interesting. Master of heavily researched deep-dive blog posts, his relentless consumer advocacy has ruffled more than a few manufacturer's feathers over the years. Read Ronald's full bio.


  1. Yes Minister says

    I abhor and absolutely refuse to use water saving shower heads that piddle an almost undetectable trickle, mine have had all restrictions removed so I get a veritable waterfall. That said, I don’t pay for water as the Bloke Upstairs keeps my takn full. I’m all for efficiency but not to the point where I don’t enjoy certain creature comforts.

    • Yep, agree there. Water saver showerheads are hopeless. Most people I speak to refuse to use them. It takes longer to get shampoo and soap suds off. Having a shower is a creature comfort, not about water saving.

      Cold wash clothes…. requires harsher washing chemicals. Cleaning requires three vectors:- chemicals (surfactants), pressure (agitation) and temperature. If you decrease water temperature, you need to increase the other vectors.

      Eventually, with continued cold washing, the washing machine will start to deposit black scum onto your clothes. Black scum is fatty deposits collected from dirty washing. You will need to run hot water eventually to get rid of it, possibly with other chemicals.

      Hot water washing requires less detergent, temperature affects cleaning power. (ditto for dishwashers and hand washing).

      So, who cares if I use hot solar water to do my washing fed from a rainwater tank? 0 energy from the grid from the PV system to run the washing machine, 0 energy to heat the water. 0 litres from the mains for the water from the rainwater tank. Results – 100% creature comfort – 0 cost to environment and energy. Ditto for the shower… same solution.

      Insulating the pipes – but only the copper pipes as this is where most of the heat loss will occur. Poly will inhibit the loss due to low heat conductivity vs copper’s high conductivity.(Copper piping is mandatory for solar hot water systems piping). Most new homes have black poly piping the attic, provides instant hot water in summer for a short duration (when it comes from the cold pipe), otherwise it’s hot water all the way, it’s hot from the time tap is turned on. (Defeating the purpose of the tempering valve at the hot water system for a short time).

      So, for some, it’s not about conservation but a better way to extract more value from solar for the same creature comfort. Picking pennies to avoid dollars. Nup, not cutting it for me. 8 months of the year, my hot water is entirely free (that is the booster is turned off for 8 months). Courtesy of the solar thermal hot water system and diverting excess solar PV power to the hot water tank. Which by the way, the PV system has paid for itself in 4 years (12 months ago). So, am in front now……

  2. Thanks Ron
    Excellent information

  3. Beware the instant gas hot water system which only operates the gas to heat the water when the flow of water is uneconomically high.

  4. G’day Ronald. Many thanks for another informative article for sure … though I never imagined you to be a ‘Baldrick’ with a ‘cunning plan’ 🙂

    Your article reinforces sayings that I repeat after my father that go something like … “a penny saved is 2 pennies earned” … and … “waste not – want not”. Adages I am sure that were originally forged during times of great despair and economic depression – adages lost on modern living I am afraid.

    Anyway, I could have been knocked over by a feather when you mentioned the price of water in QLD. We pay 26.3 cents for the first 50KL and then 53.8cents/KL above that threshold here in the ACT!!?? Therefore, water saving alone is a big deal here. Your article is certainly a timely reminder that I need to get busy and check all manner of things as I have 4 adolescent children still living at home – children who have never had the pleasure of using an out-house or experienced a sheep-dip bath :-).

    Anyway, thanks again mate …



    • Ronald Brakels says

      Thanks for your reply, Peter.

      My parents pay around $1.50 a kiloliter for water, which comes to 0.15 cents a liter. That’s considerably more than in Canberra, but this is because they live in what’s called a rural area, despite the fact that it looks pretty built up to me. (If I look out the window, I can see another house.)

      • Opps sorry Ronald. My comment above should have read 26.3cents/litre for usage up to and including 50KL and then 53.8cents/litre above that threshold. In other words and from my bill, we pay $2.63/KL and $5.36/KL respectively. 🙁

  5. Your articles are always entertaining and props to you for the research you do. Just thought I would put an additional hot water related electricity saving tip here.

    Electric Hot water tanks have thermostats which can be turned down. Reducing the tempurate the tank needs to heat to from 75DC down to 60DC saves me approximately 2-3kWh’s per day (taken from meter reads same time everyday over a month period).

    Note: As electricity is involved, licenced electrician should be contacted.

  6. Ive had no trouble giving up many things in the pursuit of being efficient but giving up a satisfying shower to start the day is talking things beyond reasonable, I stayed with my parents for a few months and they had one of those water saver shower heads and it was a lot more like being pissed on than a shower.

    One of the few modern pleasures worth holding onto I think!

  7. No choice but long showers... says

    For medical reasons a member of the family has long showers, that I can’t do about. So I was motivated to find a some savings without affecting their experience too much.
    It’s fair to say that if all your systems are working as they should and you have no leaks, and people aren’t taking long showers…you won’t save much. But it is all incremental and savings do add up over a long period. It’s a good return for not much work. Not too mention it is satisfying to pay the utilities less, no matter how little.
    I have found some older HW water systems have the temp set quite high. I’ve come to realise that is about capacity in some situations. But it may not be necessary. It’s not unusual to find our gas system cranked up to 70’c+ if we had some work done on it. Some thing to watch out for.

    I have the Methven ultra low flow shower heads. I bought them through the ATA. They are expensive, but they do work surprisingly well and the design is clever. However, I have used the plastic disks and there’s no doubt they will do the job quite ok for most at a fraction of the price, if you are willing to experiment.

    In terms of water savings, one thing that is not often mentioned is that in Victoria at least the sewage disposal charge is linked to how much water you use, so there are savings there as well.

  8. Hey Peter,
    you may want to sit down before you read further,

    in Brisbane, we pay $3.51 a kilolitre, IE $2.75 State bulk water charge a kilolitre, and 76c a kilolitre distribution charges, and then $51.63 quarterly access charges. That’s if your good, if you exceed a quarterly consumption threshold, then the price really goes up. I don’t know the figures for that, I have never dared get close. So an open hose with good volume and pressure will cost $10 an hour on your lawn. Very few people water their lawns any more up here.

    • I wrote this before I saw your correction.

      • G’day Mark, thanks for the comparison mate. Again, “Holy Sheep” it appears you guys are copping it in the neck even worse than us Canberrans.

        I should have mentioned that we also pay a flat quarterly ‘supply charge’ of $26.06 and a separate quarterly ‘sewerage charge’ of $134.34, both of which do not attract GST.

        On re-reading my bill, I stand correct as the costs I cited previously as I did not include GST … so it is even more expensive, I am afraid.

        Cheers mate …


  9. black poly pipes , piping hot water

  10. coiled black poly pipes in the sun = piping hot water

  11. Not all low-flow shower heads are created equal!

    Having tried several, I can certainly empathise with those who don’t like them. There are few experiences less satisfying than a bad shower and sadly a lot of low-flow heads deliver this soul-crushing experience.

    However, for the last several years I have been using and enjoying one particular type, to the point where I can actually recommend it to others. This is an independent recommendation and I have no relation to the company.

    They are very cost effective and very efficient, and most of all they actually feel like you are having a proper decent shower!

    I have found only one downside so far, there is a chrome coating which eventually discoloured and flaked off (it could be after me using an improper cleaning product like CLR??) so I replaced one after years of service – but they are not expensive so I still found this a worthy investment.

    And – full disclosure – my wife was less keen on it when she had long hair, as with a lower total flow it takes longer to rinse out shampoo. My solution to that was to install a hand-held shower (regular 9 L/m) and flow diverter, now we are both delighted with the results. True win-win.

  12. Shower every second day and save lots of water and energy.
    Shave in the basin rather than under the shower.
    Have a cold/tepid shower rather than a hot one.
    Have your final rinse with cold water to invigorate your day.
    If on time of day tolling use pool pump, dishwasher and washing machine after 8pm (or whatever time takes you to the lower/est price.

  13. I’m a masochist,but re-tired, so I guess I can get away with the following:
    I have a solar hot water system with a ground tank on controlled load and if we have bright hot days I simply turn the circuit breaker off. This can give several days of zero power use even when using a fair amount of hot water at night. The control signal does not operate on weekdays until 11.00pm so occasionally I get caught out with lukewarm water. The washing gets done on Mondays and as the signal cuts in early in the day, on Sunday, I test to see if it needs to heat and leave it for a few hours then check again. The old rotary meter gives a very good check on whether the tank needs power. My spouse is an ex RN and likes washing some clothes with HOT water.
    I guess also that being re-tired we use a lot less than a family.

  14. Well if you have an existing electric hot water system or solar hot water with a storage tank with an electric booster.
    I think they are usually installed with a timer that allows you to set it up to heat up when ever you wish.
    So irrespective of cloudy days I find setting the timer around the mid day for a couple of hours. Gives me my best bang for outlay both in cost and ease.
    The deficit between the wattage is bought from the grid true but it is supplemented by whatever your panels are producing. I don’t have to outlay any new gadgets etc. And from most of what I reading they simply arent worth the cost pretty much like the battery story at this stage.
    Thanks for the topic and to all for interesting read.

  15. If you wat to save water collect rain water. Funny you never mentioned it. It rains in Australia correct?

  16. arbicamriea says

    The major advantage of using lower pressure shower heads is obvious: Since the head allows smaller amounts of water to flow through it as compared to other heads, the restricted flow ultimately reduces your water use.If you are interested in getting knowledge about the best shower head for low flow shower heads Australia. Click here.

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