Yellow Water Coming From Your Water Heater? Here’s What It Could Mean7 min read

Discovering yellow water coming from your water heater definitely points to an underlying issue: it could be sediment buildup, rust, corrosion, bacteria growth, or poor water quality. The good news is that it’s not normally inherently dangerous: there’s no need to panic. But I’d say it’s a pretty clear sign that your water heater isn’t working properly, and like all issues with home appliances, you should never ignore these little warning signs.

You can fix the problem using a few options, like flushing the tank to remove sediment, testing water quality, and installing softeners or filtration devices. Quick, simple fixes that aren’t too bad at all.

I know it’s a little alarming to find yellow water coming from your water heater, but in most cases it’s completely fixable. I’ve been through this before myself in our home, and it’s actually pretty easy to fix if you can figure out the source of the problem. We’ll take a look at the possible causes, and then I’ll help you figure out what to do next.

Plumbing issues can be serious, and I take the quality of information very seriously. Therefore, I’ve had this article expertly reviewed by Mark Longhurst. Mark is a plumber with over 15 years of hands-on experience and owns PipeSmart.

Yellow Water Coming From Your Water Heater: 3 common causes

In my experience, there are a few basic causes for water discolouration in your heater. Here are the main culprits I think are usually behind it:

1. Sediment Buildup

So, if you allow sediment to build up in a water heater, this can lead to water discolouration. This is pretty common, and I’ve actually come across this in my own home. Sediment accumulates at the bottom of the tank, trapping minerals and impurities, which can turn the water yellow or brown.

Plus, the sediment can create a barrier between the heating element and the water, which can interfere with the efficiency of the heating process. This means your water heater has to work extra hard, leading to both increased wear-and-tear and bigger energy bills.

If you live in a hard water area, like we do, you’re more likely to come across this problem. Older water heaters tend to be prone to it, too. So if you live in an older home, like we do, chances are there’s an older water heater causing you some issues.

2. Rust Buildup

Bear with me here while we get technical. The interior parts of a water heater, like the tank or pipes, start to corrode and accumulate rust, and this can give a noticeable discolouration to the water: think yellow, brown, or orange.

Rust build-up not only looks a little gross, but it can also mess with the integrity of the water heater, leading to leaks and other issues.

If your loyal old water heater is nearing the end of its life, rust is a common sign that it might be time to give up and invest in a new one. 

3. Quality of Water Supply

The actual quality of your water supply can lead to water discolouration. Poor water quality – which in this case means water with high levels of minerals, sediment, and impurities – can lead to discolouration of water when it passes through the heater.

(Remember you should never drink or cook with water from the hot tap)

As an extra bit of info you might find interesting: it’s usually dissolved calcium and magnesium that cause water to become ‘hard.’ Not harmful to your health, so you don’t need to worry about that, but it’s a little annoying to live with, for sure.

This sucks, because these contaminants can react to the heating elements, leading to yellow water. And aside from moving to an area with a better supply, there’s not a lot you can do about this: you just need to keep an eye on the mineral levels over time and invest in filtration devices (but I’ll explain more about that in a second).

how to fix yellow water in your water heater

Think of discolouration coming from your water heater as a sign from the universe: it’s not an emergency, but it’s a definite sign that you need to take action. It’s important, in your whole home, to pay attention to these things, whether it’s your water heater making a knocking sound or your fridge making a burning smell. Here’s what I’d recommend you do:

Test the Water Quality and Hardness

One way to troubleshoot yellow water is to test the water quality and hardness. The first thing I would do is check the water heater for any visible leaks, damage, or sediment build-up.

Extra pro tip: check the connections while you’re there for any leaks. These areas can be prone to small leaks, but they’re super easy to fix.

As I mentioned earlier, hard water contains high levels of minerals, like calcium and magnesium, which can cause sediment buildup over time. It’s annoying to live with, but not the end of the world.

You can find water test kits (On Amazon) online or contact a professional to figure out the hardness and quality of your water. 

Professionals can do a pH test, which is a super useful tool. It can assess the acidity or alkalinity of the water supply. If they find that your water is outside of the recommended range, that’s probably what’s causing you problems. The good news is that a professional can give you some advice on what to do next, like installing pH stabilizers.

Mark Longhurst

Flush the Water Heater

Want to get rid of all that sediment build-up? Flushing it is the easiest way. I’ve done this in our water heater and it made a huge difference. Disable the power supply and water supply valve, connect a hose to the drain valve at the base of the unit, and open it to get all the water out. Once it’s empty, you can switch the supply back on and allow it to refill. This should lead to clearer water in the tank.

This Old House made a great video on how to flush a water heater:

Replace the Anode Rod

To get technical again, the anode rod is an important component in the system. It prevents rust buildup by sucking all the corrosive elements toward it, like a magnet. Unfortunately, like most appliances (and the humans looking after them), they will age.

This is what an anode rod looks like. It sits within your water heater.

Replacing the anode rod can make your water heater work like new again. But I’d say this is more of an intermediate task. You may have to call someone in for help if you don’t want to risk it.

Install a Water Softener or Filtration System

If you think that hard water is the problem, you can install a water softener or filtration system. You should get someone to do this for you; your nearest water filtration installer/supplier can check it out and do it all for you, depending on how severe the hard water situation is.

I live in a very hard water area, and I’ve been surprised at the knock-on effect this has throughout the whole house, but the water heater is a big one, alongside other issues like needing to use a ton of softener in the washing machine.

Water filters, or softeners, can address a whole bunch of annoying problems, including sediment, minerals, impurities, and discoloration. Having one professionally installed is a good call, and you can make the most of regular maintenance calls to make sure the filters are working properly. Takes the stress away from you and stops you from having to remember to check on it.

Mark Longhurst

How to Prevent Discolored Water in the Future

It’s gross having to deal with murky, rusty, or discoloured water. I don’t know about you, but I’d rather not have to deal with it again.

I think if you take a little time for some preventative measures, it can help. (I should say that it might not completely prevent the problem from coming back, especially if you live in an area with low-quality water, but it might help).

Routine Maintenance and Inspections

This sounds boring, but it honestly helps: just checking on your water will help to prevent issues from occurring. You can catch them in their early stages if you see what I mean.

I would say scheduling annual maintenance check-ups with a licensed plumber can really help. It stops you from having to deal with it, and they’ll do a really thorough job. This can prevent problems from getting worse and save you some cash in the long run, which is always good news.

Consistent Monitoring of Water Quality

It’s another little home maintenance job to remember, but testing the quality of your water rushing through your pipes can help. You can do this using the water testing kits I mentioned earlier, or you can just get a professional to do it for you.

If you do want to use a home water test, just make sure that you follow the instructions. They should have all the key info on the box for you to follow.

Follow the Best Practices

Just sticking to the rules is always a good call, I find. Don’t pour harsh chemicals down the drain, as this can cause corrosion. Follow the manual, which will give you ideas for best practices and a decent maintenance schedule to follow.

Regularly Flushing the Tank

It’s an easy job, and regularly flushing the tank will keep your water nice and pristine. I’d say doing this every six to twelve months is a good call, but that depends on the hardness of your water – I couldn’t leave the water heater in my home for a year because that would be too long. If you’re not sure, check the manufacturer’s instructions or just call a professional to ask for advice.

Replacing the anode rod

Remember the anode rod I mentioned earlier? It probably will need replacing eventually. You can do this every few years to keep your water heater working just right.

Again, though, if you’re not comfortable, you can hire a plumber to do it for you. Better to suck up the initial expense rather than having to pay for a damaged water heater!

Should You Hire a Professional for Water Heater Issues?

Some water heater problems can be fixed over a weekend with some elbow grease and the ability to deal with slightly gross-colored water, while others require professional assistance. So, how can you tell when to give in and call for help?

When to Call a Professional for Assistance

I know it’s a tough call to make, especially if you’re on a budget or (like me) you’re stubbornly trying to do everything yourself. Plus, if you’re a woman, there are some old-fashioned perspectives to consider when it comes to hiring a contractor. But I’d say if any of the following issues apply to you, you should call a professional.

  • If you’re experiencing persistent issues with your water heater, like discoloured water or inconsistent water temperature.
  • If you’re not comfortable with DIY, attempting to fix a water heater issue without the proper knowledge and tools can be dangerous, and the last thing you want to do is to cause even more damage accidentally
  • If your water heater is still under warranty, because any attempted home repairs could void your warranty, which would suck if there is a larger issue at play and you need the whole thing replacing

When in doubt? Call a plumber. They know what they’re dealing with.

How to Choose a Reputable and Qualified Service Provider

So, how do you pick a professional plumber if you don’t know any? To avoid being scammed by a poor plumber, here’s what I’d recommend:

  • Search for a plumber with a valid license, insurance, and experience handling water heater issues. They should be able to give you this information on their website or over the phone.
  • Check online reviews and ask for referrals from friends and family to find a reputable plumber that real people have used and got on well with.
  • A good plumber will be transparent about their pricing and provide an estimate before starting any work, so you won’t be hit with any huge bills unexpectedly.
  • Consider their availability and response time, as a reliable plumber should be available for emergency repairs and respond promptly to any inquiries.
  • A decent plumber will help you to save money, either upfront or in the long run, by knowing how to solve problems before they get worse.

Key Takeaways

I know it can be a little disconcerting to see yellow water coming from your water heater. It looks gross, and it doesn’t feel good to know that you have dirty water in your home. The main thing is not to worry too much. You need to take action, but it’s a huge disaster: you may be able to catch the problem early enough to sort it out.

As always, I’d recommend contacting a professional if you don’t feel confident. But as an overview, you can fix yellow water coming from your water heater by doing the following:

  • Testing the water quality to see whether sediment build-up is the culprit
  • Flush the water heater to remove some of the build-up
  • Replacing the anode rod, which is designed to attract all the minerals that can damage your water heater
  • Install a water softener or filtration system, either yourself or by contacting a plumber

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Hi, I'm Ed, and I run BuildFanatic! I enjoy providing the best possible information on a range of home improvement topics.

Mark Longhurst
Plumber at | Website | + posts

Mark Longhurst is a professional plumber with over 15 years of experience, owns Pipesmart, and is our resident expert in all things plumbing.

Mark helps review plumbing-related articles for BuildFanatic to ensure we're providing our readers with the most accurate and updated advice.

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