What Is TDS in Water? A Calgary Homeowner’s Guide
TDS stands for total dissolved solids. It’s the combined weight of every mineral, salt, and metal dissolved in your water, measured in parts per million (ppm) or milligrams per litre (mg/L). Two numbers that mean the same thing.
In plain terms, if you boiled a litre of tap water until it fully evaporated, the dusty residue left behind is the TDS. For most Canadian homes, that’s a mix of calcium, magnesium, sodium, and bicarbonates picked up as water moves through soil, pipes, and treatment plants. It isn’t inherently bad. It’s just a measurement.
TDS (total dissolved solids) is the combined weight of every mineral, salt, and metal dissolved in your water, reported in ppm or mg/L. Most tap water runs 100-400 ppm; Calgary’s sits at 150-250 ppm depending on which treatment plant serves you. Health Canada, the WHO, and the EPA all treat TDS as an aesthetic parameter rather than a health one, with 500 ppm as the usual ceiling for taste and appliance impact. A $15-$25 pen meter gives you a home reading in seconds, and reverse osmosis is the most effective way to reduce TDS (90-99% reduction) if your number’s bothering you.
What Does TDS Actually Measure?
TDS captures everything dissolved in water that isn’t H2O itself. The reading rolls up dozens of separate compounds into one number, which makes it a useful snapshot but a rough one.
Here’s what’s usually inside that number:
- Calcium and magnesium — the main drivers of hard water and kettle scale
- Sodium and potassium — naturally present; also added during softening
- Bicarbonates, carbonates, and sulfates — typical in river-fed systems like Calgary’s
- Chlorides — from source water and road salt runoff
- Nitrates — usually low in municipal supply; higher in some rural wells
- Trace metals — iron, manganese, zinc; elevated only in specific conditions
A standard TDS meter doesn’t separate these. It passes a small current through the water and measures electrical conductivity, then estimates dissolved solids from that. That’s why a lab test tells you more than a pen meter ever will.
TDS Levels: What’s Normal, What’s Not
There’s no single “correct” TDS number. There are ranges, and they map to how the water tastes and performs more than to safety. Health Canada and the WHO both treat TDS as an aesthetic parameter, not a health one (more on that below).
| TDS Range (ppm) | What It Means |
|---|---|
| Under 50 | Very low; flat taste; close to distilled |
| 50-150 | Often cited as ideal for taste |
| 150-300 | Acceptable; common municipal range |
| 300-500 | Fair; noticeable mineral taste, some scaling |
| 500-1,000 | Poor; exceeds Health Canada aesthetic guideline |
| Over 1,000 | Unacceptable per WHO; consider treatment |
Health Canada sets the aesthetic objective at 500 mg/L or less in its drinking water quality guidelines, meaning water above that level tends to trigger complaints about taste, scaling, or staining. The WHO calls water “good” under 300 ppm, “fair” to 600 ppm, and “unacceptable” over 1,000 ppm. The EPA uses a secondary standard of 500 ppm in the United States. Three agencies, three nearly identical lines.
These are aesthetic thresholds. They’re about palatability and appliance impact, not illness.
Calgary-Specific: Where Our Water Falls
If you live in Calgary, your tap water typically runs 150-250 ppm TDS, well inside both the Health Canada and WHO “good” ranges.
The exact number depends on which treatment plant serves you. Homes in north Calgary — Tuscany, Rocky Ridge, Royal Oak, Evanston — draw from the Bearspaw plant, which tends to sit between 200 and 250 ppm. Homes in the south and southwest — Haysboro, Oakridge, Palliser — are served by the Glenmore plant and often read closer to 140-180 ppm.
Calgary’s water also shifts seasonally. Spring runoff from the Rockies changes mineral content in the Bow and Elbow Rivers, so a TDS reading in May rarely matches one in November. The water’s still safe either way, but the taste can move month to month.
For a deeper look at what’s in local water, including hardness and chlorine treatment, see our Calgary water quality guide.
How to Measure TDS at Home
You don’t need a lab for a ballpark reading. A handheld TDS pen meter costs about $15-$25 at most hardware stores and gives a result in seconds.
Here’s how to use one:
- Fill a clean glass with cold tap water; let it settle for 30 seconds.
- Turn the meter on and dip the tip about 2 cm into the water.
- Stir gently and wait for the reading to stabilize (usually 10-15 seconds).
- Record the number, then rinse the probe with distilled water.
Test at a few different times of year. You’ll see variation, especially in Calgary during spring. For a precise breakdown of what makes up that number (calcium vs. sodium vs. chloride), you’ll need a lab water test. Most local water treatment companies, including our team, offer that for free.
Is High TDS Bad for You?
The short, honest answer: not at typical municipal levels.
Health Canada has not established a health-based maximum for TDS. Its guideline is explicitly aesthetic — focused on taste, scaling, and staining. The WHO takes the same position: TDS becomes a palatability issue before it becomes a health one, and the “unacceptable” threshold of 1,000 ppm is still an aesthetic call.
That said, TDS isn’t meaningless.
- Taste suffers above ~300 ppm. Coffee, tea, and drinking water all pick up a mineral or metallic edge.
- Appliances wear faster. Kettles, coffee makers, humidifiers, and dishwashers accumulate scale. Scale cuts efficiency and shortens lifespan.
- Plumbing fixtures show it. White deposits on faucets, spotty glassware, and cloudy ice cubes are all downstream of dissolved minerals.
- Very high readings can flag contaminants. If TDS jumps well above local norms, something has changed. A lab test can pinpoint what.
For homes with a private well, high TDS deserves more attention. Well water can carry elevated sodium, nitrates, or sulfates, and a TDS meter reading above 500 ppm is a reasonable trigger for a full lab panel.
How to Reduce TDS at Home
If your goal is to lower TDS, not every filter does the job. Here’s how the common options compare:
- Carbon pitcher filters (Brita-style): Improve taste and remove chlorine. They barely touch TDS — expect 0-10% reduction at best.
- Whole-home water softeners: Swap calcium and magnesium for sodium through ion exchange. They reduce hardness dramatically but leave total TDS roughly the same.
- Reverse osmosis (RO) systems: The most effective option for TDS reduction. A residential RO unit removes 90-99% of dissolved solids, dropping Calgary’s typical 150-250 ppm down to 10-30 ppm at a dedicated kitchen tap.
- Distillation: Removes nearly all TDS but is slow and energy-intensive for whole-home use.
For most homeowners who care about TDS specifically, RO is the practical answer. If hard water scale is the bigger complaint, a softener handles that. Many Calgary homes run both — a softener for the whole house, RO for drinking water. Our benefits of a reverse osmosis system guide covers the full trade-offs, and our deeper Calgary RO water-quality walkthrough has neighbourhood-level test data.
Get a free in-home water test
We check TDS, hardness, chlorine, and the full Calgary panel — then tell you honestly whether filtration is worth it.
TDS vs. Hard Water: What’s the Difference?
These two terms get mixed up constantly.
Hard water refers only to calcium and magnesium. It’s what causes scale in your kettle, spots on your dishes, and that slippery feel after a shower. Hardness is usually measured in mg/L of calcium carbonate or in grains per gallon.
TDS is the umbrella number. It includes calcium and magnesium, plus sodium, potassium, bicarbonates, chlorides, sulfates, nitrates, and trace metals. Every drop of hard water has TDS, but not all TDS counts as hardness.
A softener fixes hardness. An RO system fixes total TDS. They solve different problems, and many Calgary homes benefit from both. You can see how we pair them on our water softener and reverse osmosis options page.
Frequently Asked Questions
What is a good TDS level for drinking water?
Most guidance points to 50-300 ppm as the sweet spot for taste and appliance performance. Under 50 ppm tastes flat. Over 500 ppm exceeds the Health Canada aesthetic guideline and usually produces noticeable mineral taste or scaling.
What is TDS in water in ppm?
TDS in ppm (parts per million) is exactly the same as mg/L (milligrams per litre). A reading of 200 ppm means 200 milligrams of dissolved solids are present in every litre of water. The units are interchangeable at normal drinking water concentrations.
Is 200 TDS water safe?
Yes. 200 ppm is well under Health Canada’s 500 mg/L aesthetic objective and falls inside the WHO’s “good” range. It’s also typical for Calgary tap water, especially from the Bearspaw plant.
How do you test TDS at home?
Use a handheld TDS pen meter ($15-$25 from most hardware stores). Dip the probe into a glass of room-temperature water, wait for the reading to stabilize, then record the number. For a breakdown of what’s actually dissolved in that number, you’ll need a lab water test.
Does boiling water reduce TDS?
No. Boiling kills bacteria and drives off some dissolved gases, but it actually concentrates dissolved solids as water evaporates. To reduce TDS, you need reverse osmosis, distillation, or deionization.
What’s the TDS of Calgary tap water?
Calgary tap water typically reads 150-250 ppm. North Calgary homes on the Bearspaw plant tend to run 200-250 ppm; south Calgary homes on Glenmore run 140-180 ppm. Spring runoff can push numbers up temporarily.
Is high TDS water unhealthy?
Not at municipal levels. Both Health Canada and the WHO treat TDS as an aesthetic parameter. Above 1,000 ppm, WHO considers water “unacceptable” for palatability, and a lab test is worth running to identify which specific compounds are elevated.
Your Next Step
If you’re curious about your own water, start with a free water test from our team. We check TDS, hardness, chlorine, and a full panel of typical Calgary minerals, then walk you through the results. No pressure, no upsell — just a clear picture of what’s in your water and whether filtration is worth it for your home.
Alberta Indoor Comfort has served Calgary, Airdrie, Cochrane, Okotoks, Chestermere, Langdon, and Bragg Creek for 30 years. Rated 4.9 stars on Google.
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Sources: Health Canada — Guidelines for Canadian Drinking Water Quality: TDS | WHO — Total Dissolved Solids in Drinking-water | City of Calgary — Drinking water quality | US EPA — Secondary Drinking Water Standards
