By Op Waters
ZeroWater filters are designed to remove virtually 100% of the Total Dissolved Solids (TDS) in your water — that’s what gives them their signature “0” reading on the included TDS meter. Because of that, they naturally filter slower than a standard carbon pitcher. If it takes around half an hour to empty a full reservoir, that’s completely normal.
If yours is running slower than that, or has slowed down noticeably over time, here are the 10 most common causes and how to fix each one.
1. Water Quality
The more dissolved solids and sediment in your tap water, the harder your filter has to work — and the faster it clogs. This is especially common with well water or hard water.
As a rough guide, here’s how tap water TDS affects how much water you can expect from a filter before it needs replacing:
| Tap Water TDS (ppm) | Contaminant Level | Approx. Filter Lifespan |
| 0–50 | Low | 40+ gallons |
| 51–200 | Moderate (typical U.S. tap water) | 25–40 gallons |
| 201–300 | High | 15–20 gallons |
| 301–400 | Very high | 8–15 gallons |
| 400+ | Extreme | Under 8 gallons |
(These are general estimates — actual lifespan depends on your specific water and filter model.)
Test your water regularly with the included TDS meter so you know when a filter is due for replacement rather than guessing.
2. Air Trapped in the Filter
Air bubbles can get trapped in a filter — new or old — and slow or stop water flow entirely. Two easy fixes:
Tapping: Remove the filter, tap it gently against a hard surface to dislodge the air pocket, then hold it under running tap water briefly before reinstalling.
Squeezing: Hold the filter by its midsection and squeeze it gently 4–5 times while water passes through, to help push the trapped air out. Don’t tap or squeeze too hard — it can damage the filter.
3. Incorrect Installation
If a filter isn’t seated properly, water can leak around it instead of through it. When installing a new filter:
- Remove all packaging and the protective cap before inserting
- Twist the filter gently into place from below — don’t drop it in from above
- Make sure the o-ring and gasket are fully seated against the reservoir for a complete seal
4. Hot Water Damage
ZeroWater filters (like most pitcher filters) are built for cold water only. Running hot water through one can damage it permanently — sometimes making it slower (from internal damage), and sometimes making it faster but far less effective (from small tears letting water through unfiltered). Stick to room-temperature or cold water.
5. New Home Plumbing
If your plumbing was recently installed or worked on, residual debris in the pipes can clog a filter quickly. Let the tap run for a minute before filling your pitcher for the first few uses after any plumbing work.
6. Filtering Liquids Other Than Water
Coffee, soda, and other beverages aren’t what these filters are designed for, and running them through will clog the filter much faster than water alone. Stick to filtering water only.
7. Heavy Use
Frequent, high-volume use means the filter reaches its contaminant capacity faster. If you’re regularly getting through a full reservoir in a short time, expect to replace the filter more often than the standard interval — use the TDS meter to confirm when it’s actually due rather than guessing by date alone.
8. Waiting Too Long to Replace the Filter
Every filter has a practical capacity limit. Once it’s absorbed as much as it can, flow slows down as a natural sign it’s due for replacement — not a malfunction.
9. A Defective Filter
Occasionally a filter is simply defective, with no clear installation or usage cause. Signs include unusually low pressure, an odd taste or smell in filtered water, or cloudy/discolored water. If you’re seeing these before you’d normally expect a replacement, swap the filter rather than troubleshooting further.
10. Trapped Sediment
Visible particles in the filtered water usually mean sediment has built up inside. Rinse the filter gently under water running in the reverse direction of normal flow to help dislodge it — carefully, since aggressive rinsing can damage the filter media.
Can a ZeroWater Filter Make You Sick?
Used correctly, no — but it’s worth understanding what it does and doesn’t do.
ZeroWater filters are designed to reduce dissolved solids, certain heavy metals, and chlorine taste from water that’s already been treated — like standard municipal tap water. What they’re not designed to do is disinfect water or remove bacteria and viruses. That distinction matters if you’re on a private well, since well water isn’t treated the same way municipal water is. (If you’re not sure what’s actually in your water, start here.)
The one real way a filter pitcher can make you sick isn’t the filter itself — it’s mold or algae growing in a reservoir that hasn’t been cleaned regularly. That’s an easy, avoidable fix: rinse the reservoir with mild soap and water every couple of weeks, not just when you swap the filter.
FAQ
How do I know when to clean vs. replace my filter? If flow has slowed but your water still tests near 0 TDS, cleaning (per the steps above) is worth trying first. If TDS readings are climbing, it’s time to replace the filter rather than clean it.
How often should I replace my ZeroWater filter? Most filters are rated for around 20–40 gallons depending on your water’s TDS level — check with the TDS meter rather than going by time alone, since usage and water quality both affect actual lifespan.
Is it normal for a brand-new filter to be slow? Yes — a new filter working at full capacity is naturally slower than one that’s partially used, since it’s removing more from the water. If it’s dramatically slower than expected, check for trapped air first.
Have a filter issue not covered here? Reach out through the Contact page — I read everything.