What is the best TDS level for brewing coffee?

Total Dissolved Solids, or TDS, is a measurement of the concentration of minerals, salts, and organic matter dissolved in your brewing water. For years, the coffee industry relied on this metric as the primary indicator of water quality. The Specialty Coffee Association (SCA) has historically suggested a target of 150 ppm, though acceptable ranges often span from 75 to 250 ppm. Understanding this number is a vital step in mastering your water quality and, by extension, your coffee brewing.

However, it is important to recognize that TDS is a blunt instrument. It counts everything dissolved in the water without distinguishing between beneficial minerals like magnesium and calcium, and undesirable elements like high levels of bicarbonate or chlorine. Water with a very low TDS—below 75 ppm—often lacks the necessary minerals to pull flavor from the grounds, resulting in flat, thin, or under-extracted coffee. Conversely, water with a very high TDS—above 250 ppm—can lead to over-extraction, where the water becomes saturated with minerals and struggles to dissolve the coffee solids, often resulting in a muddled or chalky taste.

In practice, the best approach is to use a simple TDS meter to understand your baseline tap water. If your water is naturally soft or you are using a reverse osmosis system, you may find your TDS is too low. In these cases, adding a mineral packet or blending with a small amount of mineral-rich water can bring you into the sweet spot. If your water is extremely hard, you might need to use a filtration system to bring those numbers down.

Ultimately, while TDS is a useful guide, it is not the only factor. Alkalinity and pH also play massive roles in how your coffee tastes. If you find your coffee is consistently dull or lacks brightness, your water might have too much alkalinity, which neutralizes the delicate acids in your beans. Aiming for a neutral pH around 7.0 is a great secondary goal alongside your TDS target.

For the home brewer, the goal is consistency. Once you find a water profile that makes your favorite beans shine, use a TDS meter to verify that your water remains within that successful range. This removes one of the biggest variables in your brewing process, allowing you to focus on grind size and technique.