3 Dangers of Not Changing Water Filters to Know

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You might think your water filter is doing just fine and doesn’t need changing as often as the manufacturer instructs. But actually, failing to replace your filters on time – or at all – could actually mean that you’re drinking worse-quality water than you were in your pre-filter days.

In this article, we’ve shared all the dangers of not changing your water filters, and offered insight into how to know when to replace an old filter.

📌 Key Takeaways:

  • If you don’t change your filter regularly, you’re at risk of drinking bacteria that has grown on the filter’s surface or contaminants leached back into water.
  • You should replace a filter every 2-12 months on average, depending on the filter type and size, and your water usage and quality.
  • When your filter flow rate slows significantly, your water looks or tastes poor, or your filter change light turns red, it’s time to buy a new filter.

☠️ 3 Dangers Of Not Changing a Water Filter

We’ve listed the most likely dangers of not changing a water filter below.

1) Harmful Bacteria Growth on Filter Media

Whether you have a refrigerator water filter, a pitcher water filter, or any other type of drinking water filter, the damp, humid environment inside the filter is ideal for bacteria growth.

⚠️ An old filter poses a very real risk of contaminating your water with bacteria. A study on Brita filters found that out of 34 filters, 24 of these filters increased bacterial counts in water up to 6,000 CFU/ml, suggesting biofilm growth in the filter’s media.

The longer this biofilm is allowed to grow, the more bacteria are present, and the greater your risk of getting sick.

The risk of bacterial contamination is the biggest danger of not changing a water filter – and the biggest incentive to change your filter on time.

Algae growth in water filter cartridges

2) Leaching of Trapped Contaminants Back Into Water

After months of continued use, your filter materials will start to degrade. Holes may form in the media, and all the contaminants collected in the filter may begin to leak back into your drinking water.

Since most harmful chemicals and dissolved solids are invisible in water, you may not even know that this has happened. That’s right – you could be drinking dangerously high levels of chlorine, lead, and other impurities without even being aware of it.

Degraded carbon filters may also leak high levels of carbon granules into your tap water, with potential health effects.

3) Ineffective Water Filtration

Even if your old water filter somehow manages to avoid bacteria growth and degradation, the filtration process will still become less effective over time.

Why? Because the filter pores will become so clogged that water will be unable to pass through the filter at a fast rate. This will reduce the filter’s flow rate, meaning you have to wait longer to fill your glass.

📌 There’s also a risk of contaminants passing straight through the filter. This is especially likely in carbon water filters, which have limited adsorptive abilities. Once the filter’s surface area is entirely saturated with contaminants, any further contaminants in your water supply will simply pass through the filter with the water particles.

In short, if you don’t change your water filtration cartridges on time, you risk drinking water that’s contaminated with bacteria, carbon, and impurities like chlorine, which are usually trapped in the filter’s pores.

Person holding a glass of dirty water

🔂 How Often Should You Replace a Filter?

You should replace a filter every 2-12 months, depending on the filter type.

Here are a few common water filters and their average lifespans:

Filter typeLifespan
Dispenser or pitcher filter2-4 months
Faucet filter2-4 months
Under-sink filter2-12 months
Refrigerator filter4-6 months
Shower filter6 months
Whole house filter6-12 months
Reverse osmosis filter6-24 months

Your water quality and water usage will also affect how often your filter will need replacing. The filter’s size and surface area is another factor affecting its lifespan.

👉 Check out our filter change guide to learn more about how often to replace a water filter.

🔎 How to Know When to Replace a Filter

Feeling concerned that you’ll accidentally forget to replace your filter, or that you simply won’t know when your filter needs changing?

If your water filter is old and in need of a replacement, here are some signs to look out for:

Slow Water Flow

A water flow that’s significantly slower than normal is a sign that you need a new drinking water filter.

It’s expected that a filter reduces your water flow slightly, since it provides resistance and forces water to slow down as it passes through the filter pores.

But if your flow of water slows to a trickle, it’s indicative that the filter cartridge is too clogged with impurities to allow water to easily pass through, and it’s time for a fresh filter to be installed.

Low water flow

Poor-Tasting Water

You’ve probably got used to the clean taste of filtered, fresh water. If you notice that your drinking water takes on a chemical taste, or simply tastes unclean, it’s likely that you need a new filter.

An old water filter may also introduce an unpleasant odor to your tap water, which can only be solved by buying a replacement filter.

There’s no guarantee that your water will taste or smell any different when the filter is old, since contaminants like bacteria are tasteless and odorless. So don’t wait for your water to start tasting bad before you change your filter.

Particles In Water

If your filter degrades to the point of leaching contaminants and carbon particles into your drinking water, you may be able to see these particles in your glass.

Particles in your water are a key sign that you need to buy a new filter ASAP. In fact, you probably should have changed the filter a few weeks ago.

Filter Indicator Light Turns Red

Certain pitcher filters and refrigerator water filters, and some countertop or under-sink filters with a smart faucet, have an indicator light that changes color to indicate when the filter should be changed.

  • A green light indicates that the filter is still fine
  • An amber light tells you that replacement filters will be needed soon
  • A red light tells you to replace the filter now

Keep in mind that indicator lights usually work off a timer, so they can’t actually assess the filter quality and give you a completely accurate estimate of when it should be replaced. If your water quality is particularly poor or you use more filtered water than average, you might need to replace the filter before the indicator light turns red.

Under sink filter change light indicator

❔ Dangers Of Not Changing a Water Filter: FAQ

What are the dangers of not changing refrigerator water filter?

If you don’t replace a refrigerator filter, you run the risk of drinking water that’s contaminated with bacteria and other unpleasant impurities. Refrigerator filters are connected to your internal fridge system, and failing to replace your filter could result in a chemical buildup inside the refrigerator water dispenser and ice machine, deteriorating your fridge’s functionality and reducing its shelf life.

Why am I feeling nauseous when water filter needs replacing?

If you’re feeling nauseous when your water filter needs replacing, it’s likely that your filter is leaching bacteria and other unpleasant contaminants into your water supply. This counteracts the whole point of installing a water filter: to make your water safe and healthy to drink. To reduce your risk of getting sick, replace the filter a few weeks before you usually do.

How long can you go without changing your water filter?

You can go up to 12 months without changing your water filter, depending on the filter type. Always follow the manufacturer’s instructions, and don’t use your filter for longer just because you haven’t noticed a difference in your water quality. Even if your water usage is quite low, the risk of bacterial buildup will always increase once the filter’s expected lifespan is reached.

Can you get sick from a dirty water filter?

Yes, you can get sick from a dirty water filter due to the likelihood of bacteria growth inside the filter materials. This shouldn’t be an issue if you replace the filter on time. Most manufacturers offer clear instructions on when you should replace your filters.

Do water filters really need to be replaced?

Yes, water filters really do need to be replaced. Failing to replace a filter means you won’t get the same high-quality water filtration, and you’ll also be at risk of drinking water that’s contaminated with bacteria and other contaminants that have leached into your water from the degraded filter media.

If you don’t think your filter needs to be replaced, take a look at the cartridge now. It’s probably turned brown, gray, or another unpleasantly dirty color. Compare that to the fresh white of a new cartridge, and it’s easy to see how a dirty water filter could affect your health.

  • Brian Campbell
    President & CEO, CWS, CWR

    Brian Campbell, a WQA Certified Water Specialist (CWS) and Certified Water Treatment Representative (CWR) with 5+ years of experience, helps homeowners navigate the world of water treatment. After honing his skills at Hach Company, he founded his business to empower homeowners with the knowledge and tools to achieve safe, healthy water. Brian's tested countless devices, from simple pitchers to complex systems, helping his readers find the perfect fit for their unique needs.

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