Thank you for contacting ZeroWater. The most accurate way to get reading is to test the water directly inside the pitcher. You can do this by removing the reservoir from the pitcher and sticking the meter in the filtered water sitting in the pitcher. If you get a 000 reading inside the pitcher it is possible that the cup or glass you were using before had soap residue on it causing the meter to read above 000.
If you are not getting 000 in the pitcher, try the following steps to see if you can get the filter to read 000 on the meter.

Dry off the filter with a clean paper towel. Then place the filter over a clean paper cup.

Run a small amount of water directly into the filter and test the water that collects into the cup. If the meter does not read 000 it is possible that unfiltered water got into the pitcher via a leak at the O-ring. In order for filtered water to read correctly there must be a perfect seal where the filter is screwed into the reservoir. Make sure the filter is screwed in from the bottom not dropped in from the top.

ZeroWater's Ion-exchange resin filters are a reliable and efficient way to get delicious, filtered water. They work by exchanging ions in the water with regenerated ions from the resin beds, which can remove a variety of contaminants from water, including lead, nitrates, sulfates, calcium, magnesium, and other heavy metals. The exchanged ions bind with the contaminants, making them much easier to filter out. Our combination of cation and anion exchange resins can reduce 99.6% of dissolved contaminants in your water. However, when the filter is exhausted no more contaminants can be filtered out and an unpleasant smell and taste may be present. This is a common cause of overuse and can also occur by pouring hot water into the filter or freezing it. Be aware, though, that while the smell is unpleasant, it does not indicate any harm or danger. It is only time to replace your filter. Change your filter once the TDS meter reads 006.