If you've tested your Tenerife tap water with a TDS meter — or looked at the reading someone else has shared in a local Facebook group — you've probably seen a number somewhere between 450 and 650. That's high. Really high. But what does it mean in practice, and is it something you need to worry about? This guide explains it without the jargon.

What Is TDS?

TDS stands for Total Dissolved Solids. It measures the combined concentration of all dissolved substances in water — primarily minerals like calcium, magnesium, sodium, potassium, bicarbonates, and sulphates. It's measured in milligrams per litre (mg/L) or parts per million (ppm) — numerically the same thing.

TDS is not a direct measure of safety. Some dissolved minerals are completely harmless or even beneficial at low concentrations. Very high TDS — as found in Tenerife — indicates extremely hard water with a high mineral content that causes practical problems even when microbiologically safe.

Tenerife's TDS Numbers

TDS Comparison — Where Tenerife Sits

Premium bottled water30–100 mg/L
UK tap water average~240 mg/L
WHO recommended limit500 mg/L
Tenerife South (Costa Adeje, Arona, Las Américas)500–600 mg/L
After reverse osmosis filtration10–20 mg/L

Tenerife South water is consistently at or above the WHO guideline threshold of 500mg/L — and often higher. After reverse osmosis filtration, the same water reads under 20mg/L.

What 500mg/L Actually Does

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Taste
Water above 300mg/L often tastes flat or mineral. Above 500mg/L, most people notice a chalky or slightly bitter quality. This is why most expats buy bottled water for drinking.
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Appliances
When high-TDS water is heated, minerals precipitate out and bond to surfaces. Heating elements, pipes, and boilers accumulate scale faster than manufacturers expect — typically more than twice the rate of UK water.
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Hair & skin
Calcium and magnesium ions coat the hair shaft and interfere with skin's natural oils. Most people notice a difference within a month of arriving from the UK.
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Cooking
High mineral water affects the taste of boiled vegetables, pasta, and anything where the water flavour carries. Coffee and tea are noticeably different at high TDS — even with the same beans or leaves.
Is high TDS dangerous?

Calcium and magnesium — the main components of Tenerife's high TDS — are not inherently harmful and are dietary minerals. The WHO guideline of 500mg/L is a palatability guideline, not a safety limit. That said, Tenerife's water can contain other dissolved solids beyond calcium and magnesium depending on the local supply — and the effect on appliances and hair is real and measurable regardless of health status.

How to Test Your Own Water

TDS meters are available from Amazon for €10–20. You simply dip the probe into a glass of tap water for a reading in seconds. This is a reliable way to confirm what your water measures before deciding on a filter.

Typical readings in Tenerife South:

  • Costa Adeje: 480–580 mg/L
  • Los Cristianos: 500–620 mg/L
  • Arona / Golf del Sur: 510–600 mg/L
  • Playa de las Américas: 490–610 mg/L

We test on arrival when we visit for a quote — at no charge — and test again after installation to confirm the filter is performing correctly.

Frequently Asked Questions

Does a carbon filter reduce TDS?
No. A carbon filter removes chlorine, taste, and odour compounds — but it doesn't remove dissolved minerals. Your TDS reading will be essentially unchanged after a carbon filter. To significantly reduce TDS, you need a reverse osmosis system, which reduces it from 500+ to under 20mg/L.
What TDS level is ideal for drinking water?
Most water quality guidelines suggest 150–300mg/L as optimal for taste and palatability. Premium mineral waters typically sit between 100–300mg/L. Our reverse osmosis systems with remineralisation produce water in the 50–100mg/L range — clean and fresh-tasting with a balanced mineral profile, much closer to premium bottled water than Tenerife tap water.
Does a whole house filter reduce TDS?
A whole house filter reduces the impact of high TDS water — it removes chlorine, sediment, and uses scale-inhibiting media to prevent limescale forming in appliances. But it does not significantly reduce the TDS number itself. For actual TDS reduction, you need reverse osmosis. That's why many customers have both: whole house for appliances and every tap, RO for ultra-pure drinking water.
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Ultra Pure Water Tenerife British-owned water filtration specialists. Based in Tenerife South, serving Costa Adeje, Los Cristianos, Arona, Playa de las Américas and surrounding areas.

Reduce Your TDS from 500 to Under 20

Our reverse osmosis system installed under your kitchen sink takes Tenerife's 500–600mg/L water to under 20mg/L — from the tap you use every day. €399 fully installed.

WhatsApp Us Now See Pricing →

Based in Tenerife South. We typically reply within the hour.

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