A reading of 000 or 0000 on your TDS meter is actually a sign that your ZeroWater filter is working perfectly. Here's what it means and when to be concerned.

<h2 id="a-reading-of-000-is-a-good-thing">A reading of 000 is a good thing</h2><p>ZeroWater is the only water filter brand that consistently removes virtually all dissolved solids (TDS) from your tap water. When your TDS meter shows <strong>000</strong> or <strong>0000</strong>, it means your filter is removing 99&#x2013;100% of dissolved solids &#x2014; exactly as it should.</p><p>The free TDS meter included with every ZeroWater pitcher lets you monitor filter performance and know exactly when to replace your filter.</p><h2 id="what-if-000-seems-wrong">What if 000 seems wrong?</h2><p>If you&apos;ve been using your filter for a long time and it suddenly shows 000 again, the most likely explanation is that the meter needs recalibrating or the battery is low. Try the following:</p><ul><li>Test a glass of unfiltered tap water &#x2014; it should read well above 000 (most tap water reads between 100&#x2013;400). If tap water also reads 000, your meter battery may be dead or the meter needs checking.</li><li>Rinse the meter probes with filtered water and dry them before testing.</li><li>Check if the HOLD button is not activated by pushing it once and retesting</li><li>Not seeing any numbers after turning on the meter, check the battery: remove the cap at the bottom of the meter and replace the battery if needed (LR44 button cell).</li></ul><h2 id="when-should-i-replace-my-filter">When should I replace my filter?</h2><p>Replace your filter when the TDS meter reads <strong>006 or higher</strong> on your filtered water. A reading of 000&#x2013;005 means your filter is still working well.</p><h2 id="my-tap-water-already-reads-000--is-that-normal">My tap water already reads 000 &#x2014; is that normal?</h2><p>This is very rare but possible if you live somewhere with exceptionally soft water. In that case, filtered water will also read 000 &#x2014; your filter is still working, there&apos;s just very little to remove. You can confirm by testing with a known mineral water.</p><h2 id="still-have-questions">Still have questions?</h2><p>If your TDS meter is behaving unexpectedly, our customer service team is happy to help &#x2014; <a href="https://www.zerowaterfilter.com/pages/contact">contact us here</a>.</p>

Why does my TDS meter show 000 or 0000?

Your TDS meter tells you exactly when it's time for a new filter. Replace when filtered water reads 006 or higher — not based on time or litres used.

<h2 id="use-your-tds-meter-not-a-calendar">Use your TDS meter, not a calendar</h2><p>Unlike many other filters, ZeroWater filters don&apos;t have a fixed lifespan based on months or litres. The only accurate way to know when to replace your filter is to test your filtered water with the included TDS meter.</p><h2 id="the-replacement-rule">The replacement rule</h2><ul><li><strong>000&#x2013;005:</strong> Filter is working perfectly. No action needed.</li><li><strong>006 or higher:</strong> Replace your filter. At this point, dissolved solids are starting to pass through.</li></ul><h2 id="how-long-does-a-filter-typically-last">How long does a filter typically last?</h2><p>Filter lifespan depends entirely on your local tap water quality. The higher your tap water TDS, the more work your filter does &#x2014; and the sooner it will need replacing.</p><ul><li><strong>Tap water TDS 000&#x2013;001:</strong> Clean water</li><li><strong>002&#x2013;050 (low):</strong> 150+ litres per filter</li><li><strong>051&#x2013;200 (average):</strong> 100&#x2013;150 litres per filter</li><li><strong>201&#x2013;300 (high):</strong> 50&#x2013;100 litres per filter</li><li><strong>301&#x2013;400 (very high):</strong> 30&#x2013;50 litres per filter</li><li><strong>401+ (extremely high):</strong> Under 30 litres per filter</li></ul><p>Test your tap water occasionally with the TDS meter to understand your local water quality.</p><h2 id="why-does-my-filter-run-out-faster-than-expected">Why does my filter run out faster than expected?</h2><p>If you&apos;re replacing filters very frequently, it&apos;s likely because your local tap water has a high TDS reading. This is normal &#x2014; the filter is simply doing more work. Consider our <a href="https://www.zerowaterfilter.com/products/replacement-filters?variant=50024084111688" target="_blank" rel="noopener noreferrer">multi-pack filter bundles or filter subscription</a> for better value.</p><h2 id="how-do-i-buy-replacement-filters">How do I buy replacement filters?</h2><p>Replacement filters are available on <a href="https://www.zerowaterfilter.com/products/replacement-filters?variant=50024084111688">zerowaterfilter.com</a>.&#xA0;</p>

When should I replace my ZeroWater filter?

If your TDS meter is stuck on 000 or displays HOLD, here's how to fix it.

<h2 id="the-meter-shows-hold">The meter shows HOLD</h2><p>HOLD means the hold function is activated &#x2014; the meter has locked its last reading on screen. To release it:</p><ol><li>Press the HOLD button on your TDS meter.</li><li>Test your water again normally.</li></ol><h2 id="the-meter-is-stuck-on-000-and-wont-change">The meter is stuck on 000 and won&apos;t change</h2><p>If the meter reads 000 on everything &#x2014; including unfiltered tap water &#x2014; this usually means:</p><ul><li><strong>Your TDS meter has the HOLD setting turned on.&#xA0;</strong>Press the HOLD button and test again.</li><li><strong>The battery is dead or low.</strong> Replace the LR44 button cell battery (remove the cap at the bottom of the meter). A faded or dim display is also a sign of a low battery.</li><li><strong>The probes are dirty or coated.</strong> Rinse the probes with clean water and dry them, then test again.</li><li><strong>Your tap water is genuinely very low TDS.</strong> If you live in a soft water area, tap water can read 000 or very close to it. Confirm by testing a known mineral water (e.g. Evian) &#x2014; it should read well above 000.</li></ul><h2 id="the-meter-turns-on-but-gives-inconsistent-readings">The meter turns on but gives inconsistent readings</h2><p>Make sure the probes are fully submerged and held still for 5 seconds before reading. Movement during testing can cause the reading to jump.</p><h2 id="still-having-issues">Still having issues?</h2><p>If none of the above resolves the problem, please <a href="mailto:service@zerowaterfilter.com">contact our customer service team</a> &#x2014; we&apos;re happy to help.</p>

My TDS meter is stuck on 000 / shows HOLD

Your TDS meter is the key tool for knowing your filter is working and when to replace it. Here's how to use it correctly.

<h2 id="what-is-the-tds-meter-for">What is the TDS meter for?</h2><p>The TDS meter included with your ZeroWater pitcher measures the Total Dissolved Solids in your water. Use it to:</p><ul><li>Confirm your filter is working (filtered water should read 000&#x2013;005)</li><li>Know when to replace your filter (replace at 006 or higher)</li><li>Check your local tap water quality</li></ul><h2 id="how-to-use-the-tds-meter">How to use the TDS meter</h2><ol><li>Press the <strong>ON button</strong> to turn on the meter.</li><li>Dip the metal probes at the bottom of the meter into the water &#x2014; only the probes, not the whole meter. Hold for about 5 seconds.</li><li>Read the display. The number shown is the TDS in parts per million (ppm).</li><li>Remove from the water, shake off excess water, and press ON again to turn off.</li></ol><p><strong>Always dry the probes between tests</strong> to avoid cross-contamination between samples.</p><h2 id="what-do-the-readings-mean">What do the readings mean?</h2><ul><li><strong>Filtered water 000&#x2013;005:</strong> Filter is working correctly. No action needed.</li><li><strong>Filtered water 006+:</strong> Filter is at end of life. Replace as soon as possible.</li><li><strong>Tap water reading:</strong> Tells you your local water quality. Higher tap water TDS means your filter will need replacing more frequently.</li></ul><h2 id="how-often-should-i-test">How often should I test?</h2><p>Test your filtered water once a week or every few days during heavy use. Testing your tap water once when you first set up your pitcher gives you a baseline and helps predict how long your filters will last.</p><h2 id="the-display-shows-hold-or-wont-turn-on">The display shows HOLD or won&apos;t turn on</h2><p>See our dedicated troubleshooting guide: <a href="/en-GB/My-TDS-meter-is-stuck-on-000-shows-HOLD-7747353">My TDS meter is stuck on 000 / shows HOLD</a>.</p>

How and when should I use my TDS meter?

TDS is the measure of everything dissolved in your water. Here's what it means, what's in it, and why ZeroWater removes it all.

<h2 id="what-is-tds">What is TDS?</h2><p>Total Dissolved Solids (TDS) is a measurement of all the substances dissolved in water &#x2014; expressed in parts per million (ppm) or milligrams per litre (mg/L). These dissolved solids include minerals, salts, metals, and other compounds that come from the environment, pipes, and treatment processes.</p><h2 id="whats-typically-in-tap-water-tds">What&apos;s typically in tap water TDS?</h2><p>The dissolved solids in tap water can include:</p><ul><li>Minerals (calcium, magnesium, sodium, potassium)</li><li>Heavy metals (lead, copper, chromium)</li><li>Nitrates and nitrites (from agriculture)</li><li>Fluoride and chloramine (added during treatment)</li><li>Pharmaceutical residues and industrial compounds</li></ul><p>While many of these are harmless at low levels, others &#x2014; like lead or nitrates &#x2014; are harmful even in small amounts.</p><h2 id="how-is-tds-measured">How is TDS measured?</h2><p>The TDS meter included with your ZeroWater pitcher measures the electrical conductivity of the water. Dissolved ions conduct electricity; pure water does not. A reading of 000 means virtually no dissolved ions are present.</p><h2 id="is-a-higher-tds-always-bad">Is a higher TDS always bad?</h2><p>Not necessarily. Some minerals like calcium and magnesium are beneficial to health. However, a high TDS reading may also include harmful substances &#x2014; and there&apos;s no way to know which dissolved solids are present from the TDS reading alone. ZeroWater removes them all, giving you a clean baseline.</p><h2 id="whats-the-tds-of-tap-water-in-europe">What&apos;s the TDS of tap water in Europe?</h2><p>TDS levels vary significantly by location. UK tap water typically reads between 100&#x2013;400 ppm. Softer water areas (Scotland, parts of Wales) may read as low as 20&#x2013;50 ppm; harder water areas (south-east England) can read 300&#x2013;500 ppm.</p>

What are Total Dissolved Solids (TDS)?

If your TDS meter is giving odd readings, won't turn on, or displays HOLD, here's how to diagnose the issue.

<h2 id="the-meter-wont-turn-on">The meter won&apos;t turn on</h2><p>The most common cause is a dead battery. The ZeroWater TDS meter uses a <strong>LR44 button cell battery</strong>. To replace it:</p><ol><li>Remove the cap at the bottom of the meter</li><li>Remove the old battery and insert a fresh LR44</li><li>Reattach the cap</li></ol><p>LR44 batteries are widely available in supermarkets, pharmacies, and online.</p><h2 id="the-meter-shows-a-reading-but-it-seems-wrong">The meter shows a reading but it seems wrong</h2><ul><li><strong>Filtered water reads the same as tap water:</strong> The filter may be at end of life (TDS 006+) or not seated correctly. Try reseating the filter.</li><li><strong>Tap water reads 000:</strong> This is very unusual but possible if your local water is exceptionally soft. Confirm by testing a known mineral water &#x2014; it should read above 000.</li><li><strong>Readings jump around:</strong> Dry the meter probes thoroughly, then re-test. Moisture on the outside of the probes can interfere with readings.</li></ul><h2 id="the-meter-displays-hold">The meter displays &quot;HOLD&quot;</h2><p>HOLD means the hold function is activated &#x2014; the meter is locked on its last reading. Press the HOLD button once to release it.</p><h2 id="the-meter-display-is-faded-or-hard-to-read">The meter display is faded or hard to read</h2><p>This is a sign of a low battery. Replace the LR44 battery as described above.</p><h2 id="still-not-working">Still not working?</h2><p>If the meter is still not functioning correctly after trying the above steps, please <a href="https://www.zerowaterfilter.com/pages/contact">contact our customer service team</a> &#x2014; we&apos;re happy to help.</p>

My TDS meter isn't working — troubleshooting guide

Storing your TDS meter in the fridge isn't a good idea — here's why, and where to keep it instead.

<h2 id="best-storage-for-your-tds-meter">Best storage for your TDS meter</h2><p>We don&apos;t recommend keeping your TDS meter in the refrigerator. The humidity inside a fridge can cause the battery contacts to oxidise over time, which may stop your meter from working properly.</p><h2 id="where-to-store-it-instead">Where to store it instead</h2><p>Keep your TDS meter somewhere dry and at room temperature &#x2014; a kitchen drawer near your ZeroWater pitcher works perfectly. That way it&apos;s always within reach whenever you want to check your water.</p><h2 id="still-have-questions">Still have questions?</h2><p>If your meter is already giving you trouble, see our <a href="/en-GB/My-TDS-meter-isn-t-working-troubleshooting-guide-7747331">TDS meter troubleshooting guide</a>, or <a href="https://www.zerowaterfilter.com/pages/contact">contact our customer service team</a>.</p>

Can I keep my TDS meter in the refrigerator?

The TDS meter included with your pitcher measures total dissolved solids in ppm — here's what that means.

<h2 id="what-tds-means">What TDS means</h2><p>The TDS meter included with every ZeroWater pitcher measures the total dissolved solids (TDS) in your water &#x2014; everything from minerals to metals and other impurities that are dissolved in it. The reading is shown in parts per million (ppm): the lower the number, the fewer dissolved solids are left in your water.</p><h2 id="why-this-matters">Why this matters</h2><p>Your TDS reading tells you exactly how well your filter is performing, and it&apos;s the easiest way to know when it&apos;s time for a replacement.</p><h2 id="more-information">More information</h2><p>For a full explanation of TDS and why ZeroWater removes it, see <a href="/en-GB/What-are-Total-Dissolved-Solids-TDS-7747337">What are Total Dissolved Solids (TDS)?</a>. To find out when to replace your filter based on your reading, see <a href="/en-GB/When-should-I-replace-my-ZeroWater-filter-7747319">When should I replace my ZeroWater filter?</a>.</p>

What does the TDS meter measure?

Filter lifespan depends on your tap water's TDS value — here's roughly how many litres you can expect per filter.

<h2 id="how-long-your-filter-lasts-depends-on-your-tap-water">How long your filter lasts depends on your tap water</h2><p>This depends on the TDS value of your tap water (you can measure this using your TDS meter). The TDS value indicates the level of dissolved solids present in your tap water &#x2014; the higher the TDS, the faster the filter will need to be replaced.</p><p>Check the TDS value of your tap water, then use the table below to see roughly how much water you can filter with each ZeroWater filter:</p><table><thead><tr><th>Tap water TDS</th><th>Pollution level</th><th>Capacity per filter</th></tr></thead><tbody><tr><td>000&#x2013;001</td><td>Clean water</td><td>&#x2013;</td></tr><tr><td>002&#x2013;050</td><td>Low pollution</td><td>150+ litres</td></tr><tr><td>051&#x2013;200</td><td>Average pollution</td><td>100&#x2013;150 litres</td></tr><tr><td>201&#x2013;300</td><td>High pollution</td><td>50&#x2013;100 litres</td></tr><tr><td>301&#x2013;400</td><td>Very high pollution</td><td>30&#x2013;50 litres</td></tr><tr><td>401+</td><td>Extremely high pollution</td><td>Under 30 litres</td></tr></tbody></table><p>Because filter life comes down entirely to your tap water&#x2019;s TDS, the same filter can last very differently in different places &#x2014; even with identical use. A filter that lasts several months at home on low-TDS tap water could fill up in just a few weeks somewhere with much higher TDS, such as while on holiday. Always check the TDS of the water you&#x2019;re filtering rather than assuming it&#x2019;ll last as long as it does at home.</p><h2 id="more-information">More information</h2><p>For how to know exactly when to replace your filter, see <a href="/en-GB/When-should-I-replace-my-ZeroWater-filter-7747319">When should I replace my ZeroWater filter?</a></p>

How long does a ZeroWater filter last?

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TDS meter

Which replacement filter fits my ZeroWater pitcher?

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