Noticing algae or mould in your water filter? You’re not alone. Sometimes we will have a customer call to say they have algae growing inside their benchtop gravity water filter, either at the bottom of the tank, on the mineral pad or on the filter cartridge.
While this is a rare occurrence, algae can grow in water filters under specific environmental conditions. Understanding where the algae is coming from and how to prevent and treat it is key to ensuring the quality and safety of your drinking water.
In this guide, we'll take a look at why algae sometimes grows inside your water filter, what to do if you find it and how to keep it from returning. We’ll also discuss when it might be time to think about upgrading your water filter system.
In this video, you'll find out what to do if you spot a bit of algae or mould inside your water filter. It's not something that happens all the time, but it can happen if water's been sitting in the tank for too long, especially if it's exposed to sunlight and warmth. We'll show you how to clean your filter properly – including the cartridge and mineral pad – without using any harsh chemicals.
If the algae just keeps on growing back, it might be a sign that your current water filter isn't suited for handling what's in your water. If that's the case, upgrading to a better system might be your best bet for safe, clean drinking water.
Where Does the Algae Come From?
If you're dealing with algae in your water filter, it usually boils down to two main reasons: your water supply itself or the environment around it.
1. Water Source
If you're on rainwater, rather than town water, there's a fair chance that algae or other little microorganisms are already in the water before it even hits your filter. Rainwater tanks, especially, can be prone to contamination if they're properly maintained. Leaves, debris, bird droppings and sunlight all introduce nutrients and spores into the system. If this sounds like your setup, your current water filter might just not be effective enough to deal with the biological contaminants. You might need to have a think about upgrading to something a bit more heavy-duty, like a benchtop or under-sink water filter that can offer extra pre-filtration and even UV disinfection.
2. Environment
If you're on city water, which usually gets treated with chlorine or chloramine to kill off contaminants, it's pretty unlikely that algae can get inside your system through the water itself. So, if you're still seeing algae in your filter even with town water, it's a good bet that spores from the air are finding their way into your unit. This could be happening if the lid's not on properly, the seals aren't doing their job or it's getting exposed to things like dust, air or even splashes from a nearby sink.
Why Does Algae Grow in Water Filters?
Even if your filter system starts off clean, a few things in the environment can cause algae to grow inside your filter over time.
Sunlight: Algae are sun-lovers; they use photosynthesis to grow. So, if your filter is in direct sunlight, or even getting a fair bit of indirect light, that can cause algae to grow.
Warmth: Nice warm spots, especially during summer, are ideal conditions for algae to grow, as they thrive in the heat.
No Disinfectants Left: After your filter has done its job, the water in the bottom tank is usually free of chlorine or other chemical disinfectants. When that happens, it means there's nothing left in the water to stop any little biological critters from growing once they've passed through the filter.
How to Clean a Water Filter That Has Algae Growing in It
- Disassemble the Unit: Take all the parts and components of your water filter apart – the top tank, bottom tank, filter cartridges, any mineral pads, the spout and the lid.
Clean the Housing: Grab some mild dishwashing liquid and a soft sponge or cloth (nothing too scratchy) and give the inside of the upper and lower tanks a thorough clean. Make sure you rinse it out really well afterwards; you don't want any soap left behind.
Don't Use Detergents on the Cartridges! This is important: filter cartridges, especially the ceramic types, should not be cleaned with soap or detergents. Instead, just scrub the ceramic cartridge gently under cool, running tap water. A non-scratch scourer pad should do the trick to get the outer surface clean.
Dry Everything Completely: Before you put it all back together, let every single part – especially the filter cartridge and the tanks – dry out completely. This helps to stop any tiny microbes from growing back.
Reassemble and Refill: Once everything's dry, put your water filter back together and fill it up with clean water.
Tips to Prevent Algae from Growing in Your Water Filter
After you've cleaned your filter, the next job is to stop the algae from ever coming back. Here are a few handy tips:
Keep it Out of Direct Sunlight: Find a spot for your filter system that's away from windows and out of direct sunlight. Algae loves light, so a cool, shady spot is perfect.
Use an Opaque Cover: If your filter tank is a bit see-through, think about covering it with a dark cloth or even a tea towel to block out the light.
Clean it Regularly: Even if you can't see any algae, make it a habit to clean your water filter every few weeks. This will help stop any early-stage growth that you might not even notice yet.
Don't Let Water Sit Around for Ages: Use your filtered water regularly to keep it fresh. Stagnant water is more likely to get contaminated. If you're heading off on holidays or know you won't be using the water for a some time, empty the system out and let it dry.
When to Upgrade Your Water Filter
If you've tried all the cleaning tricks and prevention tips, but the algae in your water filter keeps coming back, it could be a sign of a bigger issue:
Your current water filter might not be enough for your water quality.
The system might be too exposed to things in the environment that you can't really control.
The filter cartridges might be past their use-by date and not working as well as they should.
If any of these sound familiar, upgrading to a more advanced filter system could be your best move. High-performance systems might have advanced features like activated carbon, silver-impregnated ceramics, sediment pre-filters or even UV sterilisation – which can all help manage microbial contamination more effectively.
Need Help? We’re Here for You
If you're still wondering about what's causing algae to grow in your water filter, or how to sort it out, don't hesitate to contact us. Send us an email with a photo, and we'll have a look for you.
It might just be that this particular water filter isn't enough for the contaminants in your water. If you bought it through us, we can even look at giving you a refund on your current water filter and helping you upgrade to something better as our way of helping you out.
We want to make sure you're drinking the safest, cleanest water possible, because at the end of the day, that’s what water filtration is all about.
Seeing algae in your water filter can be surprising, but it’s usually easy to fix and prevent with the right care and placement. Keep your filter clean, out of the sun and make sure it’s suited for your water source.
If all else fails, don’t hesitate to explore a better solution for your home. After all, peace of mind and healthy hydration start with proper water filtration.
Got more questions? Contact us — we’re happy to help.
Why is Algae Growing in My Filter if I Use Town or City Water?
If you're on mains water, the algae likely isn’t coming from the water supply, as it’s typically treated with disinfectants like chlorine. More likely, the algae spores are coming from the surrounding environment, such as air, dust or exposure to sunlight, and are growing in your filter once the disinfectants are removed during the filtration process.
How Often Should I Clean My Water Filter to Prevent Algae?
It’s a good idea to clean your filter system every 2–4 weeks, even if you don’t see algae. Regular cleaning helps prevent the build-up of contaminants and ensures your drinking water stays safe and fresh.
Where Should I Place My Water Filter to Avoid Algae Growth?
Always keep your water filter in a cool, shaded area away from windows and direct sunlight. You can also use a cloth or cover to shield the system from light. Avoid placing it near heat sources like stovetops or appliances.
