Total dissolved solids (TDS) include a wide range of minerals and other inorganic compounds naturally present in water. Common examples include:
- Calcium
- Magnesium
- Sodium
- Chloride
- Iron and manganese
- Carbonates
- Nitrates
TDS isn’t generally a health concern in your drinking water. However, a high TDS level can impact your water’s taste, the efficiency of your water-using appliances and your hair and skin health. You may not notice elevated TDS levels until after these issues occur.
Here’s what to know about TDS in water, including where it comes from, how it’s measured and what to do if levels are too high.
What are total dissolved solids?
Total dissolved solids is a measure of the inorganic matter dissolved in your water, such as minerals, metals and salts. This is often expressed in milligrams per liter (mg/L) or parts per million (ppm), which represents the total amount of dissolved solids in a given volume of water.
As water moves through the environment, it picks up these materials from rocks, soil and other natural formations before reaching your tap, which can result in high TDS levels.
Where does TDS come from? Sources of TDS in drinking water
The “solids” in total dissolved solids can be found almost everywhere in nature and the environment. These areas include:
Rocks, bedrock and soil
Water from wells or municipal systems travels through layers of rock, bedrock, soil and other natural formations, dissolving minerals along the way.
Limestone (calcium carbonate) and halite (sodium chloride) dissolve most readily, so areas rich in these substances may have higher TDS levels. In contrast, regions with rocks less prone to weathering — such as quartz-rich granite — tend to have lower TDS concentrations.
Seawater
Wells near coastal regions may have elevated TDS levels because saltwater intrusion allows a high mineral content to mix with groundwater. Ocean spray and mineral deposits can also increase TDS concentrations throughout nearby water systems.
Human activity
Activities like agriculture, mining and manufacturing can add to the TDS concentration in local water sources. Even road salts used in winter or fertilizer runoff can raise TDS levels in groundwater and surface water.
Is TDS safe?
It’s important to note that by itself, a TDS level is just a measurement of the dissolved solids in your water — not a statement on whether those substances are “good” or “bad.” Many of these dissolved solids are generally not harmful to drink on their own. For instance, calcium and magnesium are common in some bottled mineral waters for taste. However, some contaminants that can be part of TDS, such as nitrate and sodium, could potentially cause negative health effects and require further water testing.
Both the Environmental Protection Agency and Guidelines for Canadian Drinking Water Quality maintain aesthetic limits on TDS levels, which refer to problems like off tastes and odors. These organizations don’t set primary standards for TDS, which generally means the substance in question isn’t a significant risk to health.
What is a good TDS value for water?
A good TDS value for water is typically around 500 mg/L. This is the National Secondary Drinking Water Regulation set by the U.S. EPA and an Aesthetic Objective set by the Guidelines for Canadian Drinking Water Quality. This number also falls within the World Health Organization’s TDS flavor classification, which is as follows:
- Excellent: Less than 300 mg/L
- Good: 300-600 mg/L
- Fair: 600-900 mg/L
- Poor: 900-1200 mg/L
- Unacceptable: Greater than 1200 mg/L
As noted, these are non-mandatory standards set for substances that generally don’t significantly impact human health. However, even at these levels or below, you may experience an unpleasant taste in your drinking water or other issues that might make you want to explore filtration options.
How to tell if you have high TDS levels
As water moves through the hydrological cycle, a certain TDS level is expected and not typically a cause for concern. However, you may notice that varying TDS levels in water can have certain undesirable effects, including:
- Taste: Water’s taste can change depending on the mineral content or other TDS components. For example, too much chloride can make water taste salty, while sulfate is bitter and bicarbonate is astringent. On the other hand, low TDS can make water taste flat.
- Corrosion: High TDS concentration can corrode distribution systems, pipes, water-using appliances and more.
Scaling: TDS also contributes to scaling or mineral buildup inside pipes and water-using appliances, reducing water pressure and service life. - Cloth deterioration: The more often you wash clothes and other cloth material in water with high TDS, the abrasion from these minerals causes these items to deteriorate faster.
- Comfort: Elevated TDS levels, specifically water high in calcium and magnesium, may lead to issues like dry skin, hair and nails.
- Cleaning: TDS can cause mineral buildup, soap spots and even decreased soap lathering and cleaning product effectiveness, making cleaning even more of a chore.
Some of these issues overlap with symptoms of hard water, which is the result of too much calcium and magnesium in your water supply. That means you may need both a drinking water filtration solution and a water softening system (which targets the water throughout your home) to address both taste and corrosion as well as issues with hair, skin, laundry, and cleaning.
What is a TDS meter?
A TDS meter, or TDS tester, is a handheld device that users partially submerge in their tap water to determine its TDS level, usually expressed in ppm.
How does a TDS meter get results?
Instead of directly measuring total dissolved solids, a TDS meter measures the conductivity of substances dissolved in tap water. The higher the conductivity, the more dissolved solids are likely present.
To measure this, a TDS meter emits a small, harmless electrical current through a water sample. It tracks how well this electricity is conducted and converts that into an indirect TDS measurement.
What can a TDS meter tell you?
A TDS meter can provide a high-level view of what’s in your water. Here are a few things that TDS users can see or infer from their results:
- Whether TDS level is higher than 500 ppm
- Whether an unpleasant water taste is likely caused by TDS or something else
- Whether water filtration and water softening solutions should be considered (if hard water is suspected, a test specific to hardness is recommended as a next step)
What will a TDS meter not tell you?
A TDS tester will only measure the concentration of all total dissolved solids, but it doesn’t break this down based on which substances are present. It also won’t indicate what else is present in a water sample, so even a low TDS reading doesn’t necessarily mean that the water source is as clean as might be desired.
For example, if you were to use a home TDS tester, you’d get a result in parts per million, or ppm — but 500 ppm doesn’t tell you what those parts are, where they came from or whether you need a particular kind of water filtration.
For this reason, it’s important to understand exactly what comprises TDS and how it may impact your drinking water.
What’s the best solution for high TDS in water?
A reverse osmosis drinking water filter is a great solution for high TDS and a broad range of other water issues. Before you invest in one, it’s important to start with a professional water test.
In Culligan’s free in-home water testing, for example, your local water expert will not only test your home’s tap water for TDS, they’ll also provide information on other common issues like water hardness, iron, chlorine and other potential contaminants. That means you get a full snapshot of your water quality.
At the end, they will recommend precise water treatment options based on your specific needs.
What is reverse osmosis water filtration?
Reverse osmosis filtration, sometimes called RO, targets a broad range of contaminants and water problems. These systems don’t just address TDS; they can also reduce lead, copper, bacteria, viruses and even emerging contaminants like PFAS (also known as forever chemicals). That means RO water is cleaner, clearer and more refreshing.
On top of that, there’s no need to worry about removing flavorful minerals. Some RO systems have an optional mineral cartridge that gives you control over the taste of your drinking water.
You can also choose a smart RO system, which comes with a host of versatile, helpful features. For example, you can connect your filtration system to your phone to get updates and notifications — and you can even track your water usage and conservation goals.
FAQs: TDS levels in drinking water
Get the answers to common questions about TDS in water:
Can a water softener reduce TDS?
A water softener reduces hardness minerals like calcium and magnesium. This will likely solve issues related to hair, skin, laundry, and cleaning but doesn’t significantly lower total dissolved solids. To reduce TDS, you’ll likely need a reverse osmosis filtration system, which targets a wider range of dissolved substances.
Does boiling water remove TDS?
Boiling can remove some volatile compounds, but it doesn’t remove dissolved solids. In fact, as water evaporates during boiling, the concentration of TDS can increase slightly.
What is the difference between TDS and water hardness?
Water hardness measures only calcium and magnesium content, while TDS measures all dissolved substances, including salts, metals and minerals. That means all hard water has some TDS, but not all high-TDS water is considered hard.
Is high TDS water good for you?
High TDS water isn’t necessarily good for you. It depends on what components are included in the TDS levels in your home. TDS levels are a measurement of total dissolved solids and don’t identify individual types of matter or specific amounts. Therefore, high TDS levels don’t necessarily indicate the presence of potentially beneficial substances like minerals.
Can you reduce TDS in water?
To reduce TDS in drinking water, consider using a reverse osmosis drinking water filtration system.
Treat your drinking water with confidence
Whether you have concerns about high TDS or any other contaminants, water treatment is a smart choice. To learn more about your water quality and which solutions are right for you, start with professional help from your local Culligan water expert.
Schedule your free, in-home water test and consultation today.
