Water quality TDS and PPM readings are the fastest way to understand what is actually in the water flowing through a hotel, restaurant or cafe. Sovereign Water tests and treats water for HORECA (hotel, restaurant and catering) operators every week, and TDS is almost always the first number we look at during a site assessment. It shapes everything from how your espresso tastes to how often your steam oven needs descaling.
This guide explains what Total Dissolved Solids (TDS) and parts per million (ppm) actually measure, the ranges that matter for each application in a commercial kitchen or front of house, and the practical steps to take when your numbers are outside them. If you would rather skip straight to a professional reading, our team carries out free site assessments as part of every consultation.
TL;DR
- TDS (Total Dissolved Solids) measures everything dissolved in your water, expressed in ppm (parts per million) or mg/L.
- Roughly 50 to 150 ppm suits most drinking and brewing applications; the Specialty Coffee Association targets around 150 ppm for coffee.
- Above 500 ppm, water starts damaging equipment, dulling flavour and clogging filtration.
- TDS is a quality indicator, not a safety certificate: it will not tell you about specific contaminants.
- Sovereign Water offers a free site assessment including a professional TDS reading and treatment recommendation.
What Do TDS and PPM Actually Mean?
TDS stands for Total Dissolved Solids: the combined concentration of all inorganic salts and organic matter dissolved in water, including calcium, magnesium, sodium, chlorides and sulphates. It is expressed in parts per million (ppm) or the equivalent milligrams per litre (mg/L), so a reading of 300 ppm means 300 milligrams of dissolved material in every litre.
PPM is simply the unit, not a separate measurement. When a supplier or an engineer talks about "the ppm of the water", they almost always mean its TDS reading. The two terms travel together, which is why they cause so much confusion in hospitality procurement conversations.
The dissolved minerals themselves are not inherently bad. Calcium and magnesium contribute to taste and mouthfeel, and completely demineralised water is flat, slightly corrosive and unpleasant to drink. The question for a HORECA operator is never "how do I get to zero" but "what is the right range for each application".
How TDS Is Measured, and What a Reading Does Not Tell You
A TDS meter estimates dissolved solids by measuring the electrical conductivity of the water: more dissolved ions means more conductivity. Handheld meters cost very little and give a serviceable snapshot in seconds, which is why a TDS pen is standard kit for every Sovereign Water engineer.
The limitation matters just as much as the number. TDS tells you how much is dissolved in the water, not what is dissolved in it.
TDS is one of the key parameters for determining the technical and sensory quality of water, though it is not always a direct indicator of dangerous contamination.
A reading of 200 ppm of balanced calcium and magnesium is excellent brewing water. A reading of 200 ppm with elevated chlorides is a corrosion risk for boilers and espresso machines. That is why we treat a TDS reading as the start of a water quality conversation, not the end of one, and follow it with hardness, alkalinity and chloride testing where the application justifies it.
Ideal TDS Ranges for HORECA Applications
As a working rule, most beverage and culinary applications perform best between 50 and 150 ppm, drinking water remains palatable up to around 300 ppm, and anything above 500 ppm needs treatment before it goes near guests or equipment. The World Health Organization (WHO) rates water below 300 ppm as excellent for palatability and below 600 ppm as good.
| Application | Ideal TDS range | Why it matters |
|---|---|---|
| Espresso and filter coffee | 75 to 150 ppm | Balanced extraction and flavour; SCA target is around 150 ppm |
| Ice machines | 50 to 200 ppm | Clear, hard cubes; prevents cloudy ice and scale on evaporator plates |
| Steam ovens and boilers | Below 125 ppm feed water | Minimises scale on elements and probes |
| Drinking and table water | 50 to 300 ppm | Taste and mouthfeel guests expect |
| Dishwashing (final rinse) | Very low, often RO-polished | Spot-free glassware and cutlery |
The United States Environmental Protection Agency (EPA) sets a secondary guideline of 500 ppm for drinking water, based on taste and usability rather than direct health risk. UK mains water is typically well inside that figure, but it varies significantly by region: soft upland supplies in Scotland and the North West can sit below 100 ppm, while hard chalk-fed supplies across London and the South East regularly carry several hundred ppm, most of it hardness minerals that end up as scale.
What High TDS Does to Your Equipment
High TDS water attacks a commercial kitchen slowly and expensively. Dissolved minerals come out of solution wherever water is heated or evaporated, which is precisely what espresso machines, combi ovens, ice machines and glasswashers do all day.
The damage follows a predictable pattern. Scale forms on heating elements and boiler walls, forcing them to work harder and pushing up energy consumption. Flow restrictors and solenoid valves clog. Filtration cartridges exhaust early, and reverse osmosis membranes foul faster than their rated life. Above roughly 500 ppm the effect accelerates sharply, which is why manufacturers increasingly void warranties where feed water is out of specification.
The U.S. EPA's secondary standard for drinking water is 500 ppm TDS, a threshold set for taste and usability. For sensitive commercial equipment, the practical limits are far lower.
For an operator, the honest way to look at this is total cost of ownership. Untreated high-TDS water does not show up as a line item, but it is quietly present in every early machine replacement, every emergency descale and every energy bill. Fit-for-purpose treatment is almost always cheaper than the damage. Our Smart Maintenance programmes exist precisely to keep that equation on the right side.
TDS and Taste: The Guest Experience Side
Guests cannot quote a ppm figure, but they can taste one. Water in the 50 to 150 ppm band tastes clean and slightly sweet, carries coffee and tea flavours well, and leaves glassware sparkling. Push past 300 ppm and water starts tasting heavy or metallic, coffee turns dull and bitter as extraction chemistry shifts, and white deposits appear on glassware and table water carafes.
For coffee-led businesses this is not a marginal issue. The Specialty Coffee Association (SCA) publishes water standards precisely because water makes up over 98 per cent of a cup of coffee, and its dissolved mineral content directly controls extraction. A cafe serving identical beans on identical machines in Manchester and Maidenhead will pour two different espressos purely because of the water. Consistency across sites means controlling TDS, not hoping the mains supply cooperates.
How to Bring TDS Under Control
The right treatment depends on your starting water, your applications and your volumes, which is why we always start with a site assessment rather than a product brochure. The main tools, broadly in order of intervention:
Filtration and scale inhibition. For moderately hard UK water feeding coffee machines and combi ovens, cartridge filtration with hardness reduction or polyphosphate scale inhibition is often sufficient, protecting equipment while leaving beneficial minerals in place.
Ion exchange softening. Where hardness is the dominant component of a high TDS reading, a softener exchanges calcium and magnesium for sodium. Note that softening changes the mineral profile without significantly reducing overall TDS.
Reverse osmosis (RO). RO strips out 90 per cent or more of all dissolved solids and is the definitive answer for very high TDS or applications such as glasswasher final rinse. For beverage applications, treated water is usually blended or remineralised back up to the ideal band, because near-zero TDS water is as much a problem for taste and equipment as high TDS water.
Every one of these needs correct sizing and correct pre-treatment to perform to specification, particularly where the incoming water is challenging. Fit-for-purpose specification, not over-engineering, is the difference between a system that pays for itself and one that does not. You can see how this applies to front-of-house water in our water dispenser range.
Frequently Asked Questions
What is a good TDS level for drinking water?
Between 50 and 300 ppm is the comfortable range for taste, with 50 to 150 ppm generally considered optimal. The WHO rates anything below 300 ppm as excellent for palatability. Very low readings taste flat, while readings above 500 ppm taste noticeably heavy and indicate treatment is needed.
Is low TDS water dangerous?
No, low TDS water is safe to drink. The practical issues are taste, which becomes flat and slightly acidic, and corrosivity towards boilers, pipework and fittings. For beverage applications, RO water is normally blended or remineralised to restore a balanced mineral content rather than served at near-zero TDS.
Does a high TDS reading mean my water is unsafe?
Not by itself. TDS measures the quantity of dissolved material, not its identity, so a high reading is a prompt for proper testing rather than proof of contamination. UK mains water is safe to drink; for HORECA the concern with high TDS is equipment damage, taste and consistency.
What TDS should I use for espresso?
The SCA targets around 150 ppm, with an acceptable range of roughly 75 to 250 ppm alongside specific hardness and alkalinity values. Staying in that band protects the machine from scale while extracting balanced flavour. Water outside it produces dull or sour coffee and shortens boiler life.
How do I test the TDS of my water?
A handheld TDS meter gives an instant reading and costs very little, making it a sensible first check for any operator. For decisions about treatment, pair it with professional hardness, alkalinity and chloride testing. Sovereign Water includes full water testing in every free site assessment.
Ready to Get Your Water Numbers Right?
Sovereign Water designs, installs and maintains fit-for-purpose water treatment for hotels, restaurants, cafes and commercial kitchens across the UK, from single-machine filtration to full RO systems backed by Smart Maintenance support.
Book a free site assessment and we will test your water, explain your numbers and recommend the right solution for your application. Solutions, not just products.