So, wondering how to flush hot water system units without it turning into a whole weekend project? Fair question, and honestly, the easiest answer to how to flush water heater models with a storage tank is to just get us to do it for you! But we’re also not going to pretend you can’t do it yourself … because you can.
In fact, plenty of homeowners flush their own systems, and there are good reasons to.
- Saves you a plumber callout
- It’s decent proactive maintenance
- Once you’ve learned, it’s easier the next time!
As a general rule, once a year is enough for most homes, though on bore water or in a harder water area, every 6 months is a safer bet.
The even better news is that learning how to flush a hot water system Australia wide is pretty much the same no matter where you are or what particular storage-based unit you’ve got. What changes a bit more is how often you need to do it, since water hardness varies a lot depending on where you are.
Steps to Flush a Hot Water System Safely
1. Turn off the power and cold water supply
For electric hot water systems, switch off the power at the switchboard, not just at the unit. For gas systems, turn the gas control knob to the pilot or off setting. Then find the cold water inlet valve, usually at the top of the tank, and turn that off too. This stops more water entering while you’re working.
And a quick note if you’re here for how to flush gas hot water system units specifically. Everything we’re saying in these steps still applies, just don’t touch anything near the gas control valve or pilot assembly beyond switching it to the position we mentioned above. If in doubt on the gas side, that’s exactly the kind of thing worth leaving to us.
2. Let it sit, or handle the heat carefully
The water coming out during a flush is often still quite hot, since heat helps loosen sediment on the way out. If you’d rather not deal with hot water at all, give the system an hour or two to cool first. Either way, gloves are a good idea, and keep the drain hose pointed somewhere that won’t be damaged by heat.
3. Connect a hose to the drain valve
You’ll find the drain valve near the base of the tank. Attach a standard garden hose to it and run the other end somewhere sensible, outside, into a floor drain, or a laundry tub – anywhere that can handle a decent volume of water without causing a mess.
4. Open a hot tap or the pressure relief valve
Before you open the drain valve, open a hot tap somewhere in the house, or the pressure relief valve on the tank itself. This lets air into the system as it drains, which stops the tank from developing a vacuum that slows the whole process down.
5. Open the drain valve and let it run
Now open the drain valve and let the water flow out. It’ll probably look cloudy or a bit gritty to start with – that’s the sediment doing exactly what you want it to do. Let it keep running until the water coming out is clear. This can take anywhere from a few minutes to closer to 15, depending on how long it’s been since the last flush.
6. Deal with a clogged drain valve, if it happens
Sometimes, sediment builds up enough to partially block the drain valve itself – especially if it’s been years since the last flush. If the flow slows to a trickle, a few short bursts of opening and closing the valve can help dislodge it. If that doesn’t work, this is usually the point where it’s worth calling in a professional.
7. Close up and refill
Once the water’s running clear:
- Close the drain valve
- Disconnect the hose
- Turn the cold water supply back on
- Let the tank refill.
Leave that hot tap or pressure relief valve open until the water runs steady with no spurting or spitting – that’s your sign the air’s been properly bled out of the system.
8. Turn the power back on, but only once it’s full
Don’t skim over this one! It’s important that you don’t restore power to an electric system until you’re certain the tank is completely full. Switching the element back on with an empty tank can burn it out very quickly – and that’s a far more expensive fix than anything you saved on the DIY flush itself.
Once everything’s back on, keep an eye on the drain valve for the next day or so to make sure there’s no slow leak from reconnecting the hose.
Or, you know, you could just ask us!
With all of that said, plenty of people would rather not spend a Saturday morning duelling with their hot water system, and that’s completely fair too. Here’s what you get when you leave it to us instead:
- A properly thorough flush, not just a quick clear
- No risk of a burnt-out element from switching the power back on too early
- A trained eye on anything else that might be starting to go wrong
- One less job on your weekend list.
Beyond the flush itself, our team also checks things most homeowners couldn’t start to look at – like the sacrificial anode inside the tank. That anode quietly corrodes instead of your tank walls, and once it’s worn down, replacing it is a straightforward job that can add years to the life of your system. We’ll also check the pressure relief valve is actually functioning properly.
And whether it’s learning how to flush out a hot water system yourself or leaving the whole thing to us, the real point is doing it regularly. Sediment doesn’t just sit there quietly, it reduces your system’s efficiency, making your system work harder than it needs to, which shortens its overall lifespan.
If you’d rather skip the DIY version, or you’ve hit a clogged valve you can’t shift, get in touch with Sunshine Coast Plumbing and Hot Water. We’ll flush it properly, check the anode and pressure valve while we’re there, and have your system running the way it should.
