6 Reasons Why Your ZeroWater Filter Is So Slow – And How To Fix It


ZeroWater filters are the only filters on the market that remove 100% of the Total Dissolved Solids (TDS) in water – contaminants such as chemicals, metals and salts. However, sometimes the filtration rate on the ZeroWater dispensers and filter pitchers may be too slow.

ZeroWater filters may be slow because of air blockages (or pockets) or elevated Total Dissolved Solid(s) (TDS) levels. Incorrect installation, an old filter, and hot water or mineral damage can also slow the filtration rate. ZeroWater filters are designed to remove 100% of the TDS in water, which can result in longer filtration times than many other brands because of greater contaminant reduction.

There are 6 specific reasons why your ZeroWater filter could be too slow. Below is the complete list of all the reasons why your Zero water filter is slow, and more importantly a step-by-step guide on how to fix each problem.

What are the types of ZeroWater filters?

This article is for anyone who uses a ZeroWater dispenser or ZeroWater filter pitcher, and whose water filter is not working as it should.

ZeroWater manufactures the following filters and filter pitchers:

All of ZeroWater’s filtration units use a 5-stage filtration system. However, the ReadyPour® filter allows you to drink the treated water while it continues to filter the water contained within the reservoir.

Reasons Why Your ZeroWater Filter Is So Slow

Water Filter Pitcher

First and foremost, it is important to remember that because ZeroWater filters are designed to remove 100% of the Total Dissolved Solids (TDS) in your water, that the filtration rate is naturally SLOW.

So, if you have recently changed over to using a ZeroWater filter then this may be the reason for your slow filtration rate – and yes, half an hour for a reservoir to empty into the ZeroWater dispenser or filter pitcher is completely normal.

If this is not the case, keep reading to find out why your ZeroWater filter is so slow.

1. Trapped Air Bubbles

The number 1 reason why ZeroWater filters are slow is because of air bubbles trapped in the filter.

This can happen with both old and brand new filters, and occurs just as often in the filter pitchers as the dispensers.

Air bubbles can become trapped in your filter as the filter contents settle in transit or later during the filtration process.

Once the water level in your ZeroWater dispenser or pitcher meets an air pocket it can severely slow down or stop the flow of water through the filter. This is because of pressure above and below the air bubble.

There are a 2 ways to remove air pockets or bubbles from your ZeroWater filter:

1. Tapping

  • Lift the filter and reservoir out of the pitcher or dispenser.
  • Gently tap the side of the filter to help break up the air pocket.
  • Place the filter & reservoir in the sink and put an inch of water into the reservoir.
  • Allow the water to run through the filter and into the sink. This should displace the air pocket.
  • Reinsert the filter and reservoir into the pitcher or dispenser.

2. Squeezing

  • Carefully lift the reservoir
  • Grip the body of the filter at its mid-section
  • Squeeze the filter 4-5 times while there is water filtering through. This should displace the air pocket.
  • Reinsert the filter and reservoir into the pitcher or dispenser.

Both methods are recommended by ZeroWater — however, be careful not to tap the filter too hard as this can crack the base of your filter.

A gentle to moderate tap to the side of the filter against a firm surface (e.g. counter) is sufficient to dislodge air bubbles.

Be wary of people online advising you to pierce a hole in your ZeroWater filter. Not only will this not remove the trapped air bubble(s), but it also allows contaminants to pass through unfiltered.

2. Old Filter Needs Replacing

To be honest, the number 2 reason for slow ZeroWater filters is that they are clogged with sediment or TDS and need replacing. Delaying the replacement of your ZeroWater filter will cause the filtration rate to become increasingly slow.

Over time the available pore spaces of your water filter become filled with contaminants – making it harder for water to flow through your filter.

Ultimately, this is just your filter doing its job.

ZeroWater filters should be changed after approximately 20 gallons.

Although, this depends on how much TDS is in your water.

Unfortunately, if you have naturally high levels of sediment or TDS in your water, then your ZeroWater filter will not last as long as that advised by the manufacturer.

Here is a quick checklist for how often you should change your ZeroWater filter depending on the TDS of your tap water:

Tap Water TDSContaminant levelFilter Lifespan
000 – 001Equal to purified bottled water40 gallons or more
002 – 050Moderate40 gallons
051 – 200Normal range (USA)25 – 40 gallons
201 – 300High15 – 20 gallons
301 – 400Exceptionally high8 – 15 gallons
401 +Extreme8 gallons or less

As you can see, the amount of TDS in your water determines how much ZeroWater you get from each filter.

Because of this, ZeroWater recommends periodically testing your filtered water with your water quality meter – which they provide for free with your filter pitcher or dispenser.

When the water quality meter reads 006 or higher the filter should be replaced. It is strongly recommended that the reading not go past that point. 

I find it helpful to always have one filter on hand ready to be installed, so I don’t have to wait.

Changing your filter is easy and inexpensive – Especially since ZeroWater replacement filters are the same for every filter pitcher or dispenser. Simply click on the link below to check them out on Amazon.

ZeroWater 5-Stage Replacement Filter

3. Blockage In The Filter Housing Area

Debris can easily become lodged inside the filter housing area, especially when replacing an old water filter.

This type of blockage tends to be more common in filtration devices that require the water filter to be twisted into place – just like ZeroWater filters.

The debris gets caught in the threads of the housing. Although, blockages can still happen in any filter type.

To prevent blockages, clean the housing area every time you replace your water filter, or when installing a new one. Take particular care to wipe along the threads.

4. Incorrect Installation

Incorrect installation of a water filter typically occurs when replacing an old filter – Although, it can happen when setting-up your ZeroWater filter pitcher or dispenser for the first time.

Usually, the water filter is not threaded, or twisted, all the way in.

Unfiltered water is then unable to pass properly through the filter. In fact, incorrect installation can also result in water leaking around the filter.

To properly install ZeroWater Dispensers or Filter Pitchers:

  • Remove the lid and water reservoir from the top of the dispenser/pitcher and remove the old filter
  • Unscrew the blue protective cap (if applicable) and packaging from your filter
  • TWIST the filter into the bottom of reservoir (from below)
  • Make sure the ZeroWater filter is threaded correctly (watch out for cross-threading).
  • Tighten the filter to obtain a complete seal between the filter, o-ring and reservoir.
  • The blue filter gasket should be fully seated against the water reservoir.

DO NOT drop the filter in from above – and remember to remove all protective caps and packaging before you install the new water filter.

5. Hot Water Damage

The ZeroWater filter pitchers and dispensers are made to filter COLD WATER ONLY. Running hot water through the filter will damage the filter irreparably and one of two things will happen:

  1. Your filter will be really slow (because of damage to the filter or increased TDS).
  2. Your filter will be really fast (because hot water damage created holes in the filter and is no longer filtering water).

ZeroWater recommends only water at room temperature or colder should be filtered through their pitchers and dispensers.

Hot water can definitely damage a water filter, but a little known fact is that TDS increases as the temperature of water increases.

While this may not impact other brands of water filters, ZeroWater filters are all about reducing your TDS to ‘zero’ – this means if you have higher TDS in your water, then your water filter will be working harder to remove them and will not only reduce the filtration rate but also the total number of gallons your filter can purify.

6. Scale Deposits

Mineral ions, such as calcium and magnesium, that are naturally found in our water supply can form scale deposits on surfaces that are in regular contact with water.

These scale deposits build up over time and damage your filtration device.

Scale is white and typically appears as a hard crusty layer. So it is easy to spot around the home, such as on shower heads or faucets.

While many water filters are not designed to remove calcium and magnesium from water, ZeroWater filters ARE. This means overtime the filter can become susceptible to scale damage.

If you live in area with a water supply that has hard water (high concentrations of calcium and magnesium) then you may need to simply resign yourself to more frequent filter changes than you originally expected.

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